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Journal Cover Physics and Chemistry of the Earth, Parts A/B/C
  [SJR: 0.611]   [H-I: 26]   [6 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1474-7065
   Published by Elsevier Homepage  [3038 journals]
  • Studying seismic sources: Theory, methods and applications
    • Authors: Seabstiano D'Amico; Christos Evangelidis; Efthimios Sokos
      First page: 1
      Abstract: Publication date: October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 95
      Author(s): Seabstiano D'Amico, Christos Evangelidis, Efthimios Sokos

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.10.009
      Issue No: Vol. 95 (2016)
  • A ten year Moment Tensor database for Western Greece
    • Authors: Anna Serpetsidaki; Efthimios Sokos; G-Akis Tselentis
      Pages: 2 - 9
      Abstract: Publication date: October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 95
      Author(s): Anna Serpetsidaki, Efthimios Sokos, G-Akis Tselentis
      Moment Tensors (MTs) provide important information for seismotectonic, stress distribution and source studies. It is also important as a real time or near real time information in shakemaps, tsunami warning, and stress transfer. Therefore a reliable and rapid MT computation is a routine task for modern seismic networks with broadband sensors and real-time digital telemetry. In this paper we present the database of Moment Tensor solutions computed during the last ten years in Western Greece by the University of Patras, Seismological Laboratory (UPSL). The data from UPSL broad band network were used together with the ISOLA Moment Tensor inversion package for routine MT calculation. The procedures followed and the comparison of UPSL derived solutions with the ones provided by other agencies for Western Greece region are presented as well. The Moment Tensor database includes solutions for events in the magnitude range 2.8–6.8 and provides a unique insight into the faulting characteristics of Western Greece. Moreover it paves the way for detailed studies of stress tensor and stress transfer. The weak events' Moment Tensor included in UPSL's database are important for the comprehension of local seismotectonics and reveal the role of minor faults, which may be critical in seismic hazard estimation.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.04.007
      Issue No: Vol. 95 (2016)
  • Seismic moment tensor inversion using 3D velocity model and its
           application to the 2013 Lushan earthquake sequence
    • Authors: Lupei Zhu; Xiaofeng Zhou
      Pages: 10 - 18
      Abstract: Publication date: October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 95
      Author(s): Lupei Zhu, Xiaofeng Zhou
      Source inversion of small-magnitude events such as aftershocks or mine collapses requires use of relatively high frequency seismic waveforms which are strongly affected by small-scale heterogeneities in the crust. In this study, we developed a new inversion method called gCAP3D for determining general moment tensor of a seismic source using Green's functions of 3D models. It inherits the advantageous features of the “Cut-and-Paste” (CAP) method to break a full seismogram into the Pnl and surface-wave segments and to allow time shift between observed and predicted waveforms. It uses grid search for 5 source parameters (relative strengths of the isotropic and compensated-linear-vector-dipole components and the strike, dip, and rake of the double-couple component) that minimize the waveform misfit. The scalar moment is estimated using the ratio of L 2 norms of the data and synthetics. Focal depth can also be determined by repeating the inversion at different depths. We applied gCAP3D to the 2013 M s 7.0 Lushan earthquake and its aftershocks using a 3D crustal-upper mantle velocity model derived from ambient noise tomography in the region. We first relocated the events using the double-difference method. We then used the finite-differences method and reciprocity principle to calculate Green's functions of the 3D model for 20 permanent broadband seismic stations within 200 km from the source region. We obtained moment tensors of the mainshock and 74 aftershocks ranging from M w 5.2 to 3.4. The results show that the Lushan earthquake is a reverse faulting at a depth of 13–15 km on a plane dipping 40–47° to N46° W. Most of the aftershocks occurred off the main rupture plane and have similar focal mechanisms to the mainshock's, except in the proximity of the mainshock where the aftershocks' focal mechanisms display some variations.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.01.002
      Issue No: Vol. 95 (2016)
  • Moment tensors, state of stress and their relation to faulting processes
           in Gujarat, western India
    • Authors: Sandeep Kumar Aggarwal; Prosanta Kumar Khan; Sarada Prasad Mohanty; Zafeiria Roumelioti
      Pages: 19 - 35
      Abstract: Publication date: October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 95
      Author(s): Sandeep Kumar Aggarwal, Prosanta Kumar Khan, Sarada Prasad Mohanty, Zafeiria Roumelioti
      Time domain moment tensor analysis of 145 earthquakes (Mw 3.2 to 5.1), occurring during the period 2006–2014 in Gujarat region, has been performed. The events are mainly confined in the Kachchh area demarcated by the Island belt and Kachchh Mainland faults to its north and south, and two transverse faults to its east and west. Libraries of Green's functions were established using the 1D velocity model of Kachchh, Saurashtra and Mainland Gujarat. Green's functions and broadband displacement waveforms filtered at low frequency (0.5–0.8 Hz) were inverted to determine the moment tensor solutions. The estimated solutions were rigorously tested through number of iterations at different source depths for finding reliable source locations. The identified heterogeneous nature of the stress fields in the Kachchh area allowed us to divide this into four Zones 1–4. The stress inversion results indicate that the Zone 1 is dominated with radial compression, Zone 2 with strike-slip compression, and Zones 3 and 4 with strike-slip extensions. The analysis further shows that the epicentral region of 2001MW 7.7 Bhuj mainshock, located at the junction of Zones 2, 3 and 4, was associated with predominant compressional stress and strike-slip motion along ∼ NNE-SSW striking fault on the western margin of the Wagad uplift. Other tectonically active parts of Gujarat (e.g. Jamnagar, Talala and Mainland) show earthquake activities are dominantly associated with strike-slip extension/compression faulting. Stress inversion analysis shows that the maximum compressive stress axes (σ1) are vertical for both the Jamnagar and Talala regions and horizontal for the Mainland Gujarat. These stress regimes are distinctly different from those of the Kachchh region.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.01.004
      Issue No: Vol. 95 (2016)
  • State of tectonic stress in Shillong Plateau of northeast India
    • Authors: Santanu Baruah; Saurabh Baruah; Sowrav Saikia; Mahesh N. Shrivastava; Antara Sharma; C.D. Reddy; J.R. Kayal
      Pages: 36 - 49
      Abstract: Publication date: October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 95
      Author(s): Santanu Baruah, Saurabh Baruah, Sowrav Saikia, Mahesh N. Shrivastava, Antara Sharma, C.D. Reddy, J.R. Kayal
      Tectonic stress regime in the Shillong plateau, northeast region of India, is examined by stress tensor inversion. Some 97 reliable fault plane solutions are used for stress inversion by the Michael and Gauss methods. Although an overall NNW-SSE compressional stress is observed in the area, the stress regime varies from western part to eastern part of the plateau. The eastern part of the plateau is dominated by NNE-SSW compression and the western part by NNW-SSE compression. The NNW-SSE compression in the western part may be due to the tectonic loading induced by the Himalayan orogeny in the north, and the NNE-SSW compression in the eastern part may be attributed to the influence of oblique convergence of the Indian plate beneath the Indo-Burma ranges. Further, Gravitational Potential Energy (GPE) derived stress also indicates a variation from west to east.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2015.11.009
      Issue No: Vol. 95 (2016)
  • On the spatial distribution of seismicity and the 3D tectonic stress field
           in western Greece
    • Authors: Ioannis Kassaras; Vasilis Kapetanidis; Andreas Karakonstantis
      Pages: 50 - 72
      Abstract: Publication date: October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 95
      Author(s): Ioannis Kassaras, Vasilis Kapetanidis, Andreas Karakonstantis
      We analyzed a large number of focal mechanisms and relocated earthquake hypocenters to investigate the geodynamics of western Greece, the most seismically active part of the Aegean plate-boundary zone. This region was seismically activated multiple times during the last decade, providing a large amount of enhanced quality new information that was obtained by the Hellenic Unified Seismological Network (HUSN). Relocated seismicity using a double-difference method appears to be concentrated above ∼35 km depth, exhibiting spatial continuity along the convergence boundary and being clustered elsewhere. Earthquakes are confined within the accreted sediments escarpment of the down-going African plate against the un-deformed Eurasian hinterland. The data arrangement shows that Pindos constitutes a seismic boundary along which large stress heterogeneities occur. In Cephalonia no seismicity is found to be related with the offshore Cephalonia Transform Fault (CTF). Onshore, NS crustal extension dominates, while in central and south Peloponnesus the stress field appears rotated by 90°. Shearing-stress obliquity by 30° is indicated along the major strike-slip faults, consistent with clockwise crustal rotation. Within the lower crust, the stress field appears affected by plate kinematics and distributed deformation of the lower crust and upper mantle, which guide the regional geodynamics.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.03.012
      Issue No: Vol. 95 (2016)
  • The typical seismic behavior in the vicinity of a large earthquake
    • Authors: M.V. Rodkin; I.N. Tikhonov
      Pages: 73 - 84
      Abstract: Publication date: October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 95
      Author(s): M.V. Rodkin, I.N. Tikhonov
      The Global Centroid Moment Tensor catalog (GCMT) was used to construct the spatio-temporal generalized vicinity of a large earthquake (GVLE) and to investigate the behavior of seismicity in GVLE. The vicinity is made of earthquakes falling into the zone of influence of a large number (100, 300, or 1000) of largest earthquakes. The GVLE construction aims at enlarging the available statistics, diminishing a strong random component, and revealing typical features of pre- and post-shock seismic activity in more detail. As a result of the GVLE construction, the character of fore- and aftershock cascades was examined in more detail than was possible without of the use of the GVLE approach. As well, several anomalies in the behavior exhibited by a variety of earthquake parameters were identified. The amplitudes of all these anomalies increase with the approaching time of the generalized large earthquake (GLE) as the logarithm of the time interval from the GLE occurrence. Most of the discussed anomalies agree with common features well expected in the evolution of instability. In addition to these common type precursors, one earthquake-specific precursor was found. The decrease in mean earthquake depth presumably occurring in a smaller GVLE probably provides evidence of a deep fluid being involved in the process. The typical features in the evolution of shear instability as revealed in GVLE agree with results obtained in laboratory studies of acoustic emission (AE). The majority of the anomalies in earthquake parameters appear to have a secondary character, largely connected with an increase in mean magnitude and decreasing fraction of moderate size events (mw5.0–6.0) in the immediate GLE vicinity. This deficit of moderate size events could hardly be caused entirely by their incomplete reporting and can presumably reflect some features in the evolution of seismic instability.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.04.001
      Issue No: Vol. 95 (2016)
  • Analysis of the 2012–2013 Torreperogil-Sabiote seismic swarm
    • Authors: M. Hamdache; J.A. Peláez; J. Henares; Y. Damerdji; R. Sawires
      Pages: 101 - 112
      Abstract: Publication date: October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 95
      Author(s): M. Hamdache, J.A. Peláez, J. Henares, Y. Damerdji, R. Sawires
      This study analyses the temporal clustering, spatial clustering, and statistics of the 2012–2013 Torreperogil-Sabiote (southern Spain) seismic swarm. During the swarm, more than 2200 events were located, mostly at depths of 2–5 km, with magnitude event up to m bLg 3.9 (M w 3.7). On the basis of daily activity rate, three main temporal phases are identified and analysed. The analysis combines different seismological relationships to improve our understanding of the physical processes related to the swarm's occurrence. Each temporal phase is characterized by its cumulative seismic moment. Using several different approaches, we estimate a catalog completeness magnitude of m c ≅ 1.5. The maximum likelihood b-value estimates for each swarm phase are 1.11 ± 0.09, 1.04 ± 0.04, and 0.90 ± 0.04, respectively. To test the hypothesis that a b-value decrease is a precursor to a large event, we study temporal variations in b-value using overlapping moving windows. A relationship can be inferred between change in b-value and the regime style of the rupture. b-values are indicators of the stress regime, and influence the size of ruptures. The fractal dimension D 2 is used to perform spatial analysis. Cumulative gamma and beta functions are used to analyse the behaviour of inter-event distances during the earthquake sequence.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.01.003
      Issue No: Vol. 95 (2016)
  • Shear-tensile crack as a tool for reliable estimates of the
           non-double-couple mechanism: West Bohemia-Vogtland earthquake 1997 swarm
    • Authors: Jan Šílený; Josef Horálek
      Pages: 113 - 124
      Abstract: Publication date: October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 95
      Author(s): Jan Šílený, Josef Horálek
      Shear-tensile crack is a model for an earthquake mechanism that is more constrained than the moment tensor but that can still describe a non-shear focus. As such, the shear-tensile crack model is more robust than the moment tensor model and yields more reliable estimates for the earthquake mechanism. Such an advantage verifies the credibility of the non-double-couple component found for some events of the 1997 West Bohemia-Vogtland earthquake swarm. As expected, in several cases, a significantly resolved non-double-couple component was obtained where the moment tensor approach failed. Additionally, for non-shear sources, the shear-tensile crack model offers optimization of the Poisson number within the focus, concurrently with retrieval of the mechanism. However, results obtained for the joint inversion of the 1997 swarm indicate that resolution is low. A series of synthetic experiments indicated that limited observations during 1997 were not the cause. Rather, hypothetical experiments of both very good and extremely poor network configurations similarly yielded a low resolution for the Poisson number. Applying this method to data for recent swarms is irrelevant because the small non-double-couple components detected within the inversion are spurious and, thus, the events are pure double-couple phenomena.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.06.007
      Issue No: Vol. 95 (2016)
  • Identification of blasting sources in the Dobrogea seismogenic region,
           Romania using seismo-acoustic signals
    • Authors: Daniela Veronica Ghica; Bogdan Grecu; Mihaela Popa; Mircea Radulian
      Pages: 125 - 134
      Abstract: Publication date: October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 95
      Author(s): Daniela Veronica Ghica, Bogdan Grecu, Mihaela Popa, Mircea Radulian
      In order to discriminate between quarry blasts and earthquakes observed in the Dobrogea seismogenic region, a seismo-acoustic analysis was performed on 520 events listed in the updated Romanian seismic catalogue from January 2011 to December 2012. During this time interval, 104 seismo-acoustic events observed from a distance between 110 and 230 km and backazimuth interval of 110–160° from the IPLOR infrasound array were identified as explosions by associating with infrasonic signals. WinPMCC software for interactive analysis was applied to detect and characterize infrasonic signals in terms of backazimuth, speed and frequency content. The measured and expected values of both backazimuths and arrival times for the study events were compared in order to identify the sources of infrasound. Two predominant directions for seismo-acoustic sources’ aligning were observed, corresponding to the northern and central parts of Dobrogea, and these directions are further considered as references in the process of discriminating explosions from earthquakes. A predominance of high-frequency detections (above 1 Hz) is also observed in the infrasound data. The strong influence of seasonally dependent stratospheric winds on the IPLOR detection capability limits the efficiency of the discrimination procedure, as proposed by this study.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.04.006
      Issue No: Vol. 95 (2016)
  • QLg tomography in Gujarat, Western India
    • Authors: Sandeep Kumar Aggarwal; Prosanta Kumar Khan
      Pages: 135 - 149
      Abstract: Publication date: October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 95
      Author(s): Sandeep Kumar Aggarwal, Prosanta Kumar Khan
      We propose a novel Lg attenuation tomography model (QLg tomography) for the state of Gujarat, Western India, using earthquake data recorded by the Gujarat Seismic Network, operated by the Institute of Seismological Research in Gandhinagar. The waveform dataset consist of 400 3-component recordings, produced by 60 earthquakes with magnitude (ML) spanning from 3.6 to 5.1, recorded at 60 seismic stations having epicentral distances spanning between 200 and 500 km. Spectral amplitude decays for Lg wave displacement were obtained by generalized inversion at 17 frequencies spanning between 0.9 and 9 Hz. Lg wave propagation efficiency was measured by Lg/Pn spectral ratio categorizing as efficient ratio ≥6 for 86%, intermediate ratio of 3–6 for 10% and inefficient ratio <3 for 4% paths of total 400 ray paths. The earthquake size and quality of waveform recorded at dense network found sufficient to resolve lateral variation of QLg in Gujarat. Average power-law attenuation relationship obtained for Gujarat as QLg(f) = 234f0.64, which corresponds to high attenuation in comparison to peninsular India shield region and other several regions around the world. QLg tomography resolves the highly attenuating crust of extremely fractured Saurashtra region and tectonically active Kachchh region. The Gujarat average attenuation is also lying in between them. The low attenuation in Cambay and Narmada rift basins and extremely low attenuation in patch of Surendranagar area is identified. This study is the first attempt and can be utilized as pivotal criteria for scenario hazard assessment, as maximum hazard has been reported in highly attenuating tectonically active Kachchh region and in low attenuating Cambay, Narmada and Surendranagar regions. The site and source terms are also obtained along with the QLg inversion. The estimated site responses are comparable with observed local geological condition and agree with the previously reported site amplifications at the same sites. The source terms are comparable with local magnitude estimated from Network. The Mw (Lg) is nearly equivalent to ML (GSN) and the slight differences are noted for larger magnitude events.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2015.12.003
      Issue No: Vol. 95 (2016)
  • Determination of background concentrations of hydrochemical parameters and
           water quality assessment in the Akhuryan River Basin (Armenia)
    • Authors: Hovhannisyan Arpine; Shahnazaryan Gayane
      Pages: 2 - 9
      Abstract: Publication date: August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 94
      Author(s): Hovhannisyan Arpine, Shahnazaryan Gayane
      The determination of background values of hydrochemical parameters, to distinguish between natural concentration and anthropogenically-influenced concentrations, is highly relevant. In presented study, to estimate the background values of hydrochemical parameters in Akhuryan River Basin, log-normal probability functions on the hydrochemical parameters concentrations was applied. The study is carried out on the basis of hydrochemical data of surface water quality monitoring for the period of 2010–2013. This study highlights the usefulness of application of site-specific background concentrations for the evaluation, interpretation of surface water quality and for determination of pollution sources.

      PubDate: 2016-09-21T00:30:57Z
      DOI: 10.1016/j.pce.2016.03.011
      Issue No: Vol. 94 (2016)
  • Recent trends of extreme precipitation indices in the Iberian Peninsula
           using observations and WRF model results
    • Authors: S. Bartolomeu; M.J. Carvalho; M. Marta-Almeida; P. Melo-Gonçalves; A. Rocha
      Pages: 10 - 21
      Abstract: Publication date: Available online 27 June 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): S. Bartolomeu, M.J. Carvalho, M. Marta-Almeida, P. Melo-Gonçalves, A. Rocha
      Spatial and temporal distributions of the trends of extreme precipitation indices were analysed between 1986 and 2005, over the Iberian Peninsula (IP). The knowledge of the patterns of extreme precipitation is important for impacts assessment, development of adaptation and mitigation strategies. As such, there is a growing need for a more detailed knowledge of precipitation climate change. This analysis was performed for Portuguese and Spanish observational datasets and results performed by the Weather Research and Forecast (WRF) model forced by the ERA-Interim reanalysis. Extreme precipitation indices recommended by the Expert Team for Climate Change Detection Monitoring and Indices were computed, by year and season. Then, annual and seasonal trends of the indices were estimated by Theil-Sen method and their significance was tested by the Mann-Kendal test. Additionally, a second simulation forced by the Max Planck Institute Earth System Model (MPI-ESM), was considered. This second modelling configuration was created in order to assess its performance when simulating extremes of precipitation. The annual trends estimated for the 1986–2005, from the observational datasets and from the ERA-driven simulation reveal: 1) negative statistically significant trends of the CWD index in the Galicia and in the centre of the IP; 2) positive statistically significant trends of the CDD index over the south of the IP and negative statistically significant trends in Galicia, north and centre of Portugal; 3) positive statistically significant trends of the R75p index in some regions of the north of the IP; 4) positive statistically significant trends in the R95pTOT index in the Central Mountains Chain, Leon Mountains and in the north of Portugal. Seasonally, negative statistically significant trends of the CWD index were found in Galicia, in winter and in the south of the IP, in summer. Positive statistically significant trends of the CWD index were identified in the Leon Mountains, in spring, and in Galicia, in autumn. For the CDD index, negative statistically significant trends were seen in Valencia, in the spring, and, in Galicia and Portugal (north and centre), in summer. Positive statistically significant trends of the CDD index were found: in the east of the IP, in the winter; in the Cantabrian Mountain, in the spring; and, in the south of the IP, in summer. Regarding to the R75p index, negative statistically significant trends were found in Galicia, in winter and positive statistically significant trends in the north of Portugal, in spring and in the Central Mountains Chain and north of Portugal, in autumn. For the R95pTOT index, negative statistically significant trends were found over the Sierra Cuenca and Sierra Cazorla, in winter and positive statistically significant trends were found over the Sierra Cebollera, in winter and in Castile-la Mancha region, in spring. The results of the annual and seasonal trends of the extreme precipitation indices performed for observational datasets and the simulation forced by ERA-Interim, are similar. The results obtained for the simulation forced by MPI-ESM are not satisfactory, and can be a source of criticism for the use of simulation forced by MPI-ESM in this type of climate change studies. Even for the relatively short period used, the WRF model, when properly forced is a useful tool due to the similar results of Portuguese and Spanish observational datasets and the simulation forced by ERA-Interim.

      PubDate: 2016-08-10T11:13:00Z
      DOI: 10.1016/j.pce.2016.06.005
      Issue No: Vol. 94 (2016)
  • Regionalization of Europe based on a K-Means Cluster Analysis of the
           climate change of temperatures and precipitation
    • Authors: M.J. Carvalho; P. Melo-Gonçalves; J.C. Teixeira; A. Rocha
      Pages: 22 - 28
      Abstract: Publication date: Available online 24 May 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M.J. Carvalho, P. Melo-Gonçalves, J.C. Teixeira, A. Rocha
      In order to study climate change on a regional scale using Earth System Models, it is useful to partition the spatial domain into regions according to their climate changes. The aim of this work is to divide the European domain into regions of similar projected climate changes using a simulation of daily total precipitation, minimum and maximum temperatures for the recent-past (1986–2005) and long-term future (2081–2100) provided by the Coupled Model Intercomparison Project (CMIP5). The difference between the long-term future and recent-past daily climatologies of these three variables is determined. Aiming to objectively identify the grid points with coherent climate changes, a K-Mean Cluster Analysis is applied to these differences. This method is performed for each variable independently (univariate version) and for the aggregation of the three variables (multivariate version). A mathematical approach to determine the optimal number of clusters is pursued. However, due to the method characteristics, a sensitivity test to the number of clusters is performed by analysing the consistency of the results. This is a novel method, allowing for the determination of regions based on the climate change of multiple variables. Results from the univariate application of this method are in accordance with results found in the literature, showing overall similar regions of changes. The regions obtained for the multivariate version are mainly defined by latitude over European land, with some features of land-sea interaction. Furthermore, all regions have statistically different distributions of at least one of the variables, providing confidence to the regions obtained.

      PubDate: 2016-06-15T15:51:38Z
      DOI: 10.1016/j.pce.2016.05.001
      Issue No: Vol. 94 (2016)
  • Nanosized iron based permeable reactive barriers for nitrate removal
           – Systematic review
    • Authors: Rui Araújo; Ana C. Meira Castro; João Santos Baptista; António Fiúza
      Pages: 29 - 34
      Abstract: Publication date: August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 94
      Author(s): Rui Araújo, Ana C. Meira Castro, João Santos Baptista, António Fiúza
      It is unquestionable that an effective decision concerning the usage of a certain environmental clean-up technology should be conveniently supported. Significant amount of scientific work focussing on the reduction of nitrate concentration in drinking water by both metallic iron and nanomaterials and their usage in permeable reactive barriers has been worldwide published over the last two decades. This work aims to present in a systematic review of the most relevant research done on the removal of nitrate from groundwater using nanosized iron based permeable reactive barriers. The research was based on scientific papers published between 2004 and June 2014. It was performed using 16 combinations of keywords in 34 databases, according to PRISMA statement guidelines. Independent reviewers validated the selection criteria. From the 4161 records filtered, 45 met the selection criteria and were selected to be included in this review. This study's outcomes show that the permeable reactive barriers are, indeed, a suitable technology for denitrification and with good performance record but the long-term impact of the use of nanosized zero valent iron in this remediation process, in both on the environment and on the human health, is far to be conveniently known. As a consequence, further work is required on this matter, so that nanosized iron based permeable reactive barriers for the removal of nitrate from drinking water can be genuinely considered an eco-efficient technology.

      PubDate: 2016-09-21T00:30:57Z
      DOI: 10.1016/j.pce.2015.11.007
      Issue No: Vol. 94 (2016)
  • Identification of nitrate sources in groundwater and potential impact on
           drinking water reservoir (Goczałkowice reservoir, Poland)
    • Authors: Joanna Czekaj; Sabina Jakóbczyk-Karpierz; Hanna Rubin; Sławomir Sitek; Andrzej J. Witkowski
      Pages: 35 - 46
      Abstract: Publication date: August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 94
      Author(s): Joanna Czekaj, Sabina Jakóbczyk-Karpierz, Hanna Rubin, Sławomir Sitek, Andrzej J. Witkowski
      Goczałkowice dammed reservoir (area – 26 km2) is a strategic object for flood control in the Upper Vistula River catchment and one of the most important source of drinking water in the Upper Silesian Industrial Region (Southern Poland). Main aims of the investigation were identification of sources of nitrate and assessment of their significance in potential risk to groundwater quality. In the catchment area monitoring network of 22 piezometers, included 14 nested, have been installed. The significant spatial and seasonal differences in chemical composition between northern and southern part of the catchment were indicated based on the groundwater sampling conducted twice – in autumn 2011 and spring 2012. Maximum observed concentrations of nitrate were identified in northern part of the study area 255 mg/L as a results of inappropriate sewage management and agriculture activity. Results, based on the combines multi-scale hydrogeological and hydrochemical field studies, groundwater flow and transport modelling, dual stable isotope approach and geochemical modelling indicate mainly agriculture and inappropriate sewage water management as a sources of NO 3 − contamination of groundwater which moreover is affected by geochemical processes. In general, contaminated groundwater does not impact surface water quality. However, due to high concentration of nitrate in northern part a continues measurements of nitrogen compounds should be continued and used for reducing uncertainty of the predictive scenarios of the mass transport modelling in the study area.

      PubDate: 2016-09-21T00:30:57Z
      DOI: 10.1016/j.pce.2015.11.005
      Issue No: Vol. 94 (2016)
  • Seasonal variation in pans in relation to limno-chemistry, size,
           hydroperiod, and river connectivity in a semi-arid subtropical region
    • Authors: Tamuka Nhiwatiwa; Tatenda Dalu
      Abstract: Publication date: Available online 24 November 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Tamuka Nhiwatiwa, Tatenda Dalu
      Seasonal pans are hydrologically dynamic, with significant changes in water volume and depth in response to high evaporation, infiltration rates and inundation events. Intra-seasonal and inter-seasonal changes in endorheic and floodplain pans in relation to limnology, size, hydroperiod, and river connectivity were studied over two rainfall seasons across 36 pans at the Save Valley Conservancy. In the study region, floodplain pans were identified as pans that had connectivity with the Save River, while the endorheic pans (large and small) were hydrologically isolated basins. Seasonal trends for physico-chemical variables were initial low and gradual increased for both rainfall seasons. Significant inter-seasonal differences for several physico-chemical variables were observed. No significant differences in physico-chemical variables were observed between large and small endorheic pans, with the except for vegetation cover, which was higher in large pans. Floodplain pans differed from the endorheic systems in pH, conductivity, nutrients and suspended solids. Connectivity was found to be insignificant, as connections between these systems were probably too infrequent. Seasonal pans were uniquely distinguished by their morphometric, physico-chemical and hydrological characteristics. Inevitably, they are vulnerable to climate change with the extent of their resilience currently unknown.

      PubDate: 2016-11-27T15:42:03Z
      DOI: 10.1016/j.pce.2016.11.003
  • Living with floods – household perception and satellite observations in
           the Barotse Floodplain, Zambia
    • Authors: Xueliang Cai; Alemseged Haile; James Magidi; Everisto Mapedza; Luxon Nhamo
      Abstract: Publication date: Available online 11 November 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Xueliang Cai, Alemseged Haile, James Magidi, Everisto Mapedza, Luxon Nhamo
      The Barotse Floodplain, a designated Ramsar site, is home to thousands of indigenous people along with an extensive wetland ecosystem and food production system. Increasingly it is also a popular tourist destination with its annual Kuomboka festival which celebrates the relocation of the king and the Lozi people to higher ground before the onset of the flood season. This paper presents an integrated approach which cross validates and combines the floodplain residents’ perceptions about recent floods with information on flood inundation levels derived from satellite observations. Local residents’ surveys were conducted to assess farmers’ perception on the flooding patterns and the impact on their livelihoods. Further, a series of flood inundation maps from 1989 to 2014 generated from remotely sensed Landsat imagery were used to assess the recent patterns of floods. Results show that the floodplain has a population of 33 thousand living in 10849 small permeant or temporary buildings with a total cropland area of 4976 ha. The floodplain hydrology and flooding patterns have changed, confirmed by both surveys and satellite image analysis, due to catchment development and changing climate. The average annual inundated areas have increased from about 316 thousand ha in 1989-1998 to 488 thousand ha in 2005-2014. As a result the inundated cropland and houses increased from 9% and 6% in 1989 to 73% and 47% in 2014, respectively. The timing of the floods has also changed with both delaying and early onset happening more frequently. These changes cause increasing difficulties in flood forecast and preparation using indigenous knowledge, therefore creating greater damages to crops, livestock, and houses. Current floodplain management system is inadequate and new interventions are needed to help manage the floods at a systematic manner.

      PubDate: 2016-11-13T15:32:01Z
      DOI: 10.1016/j.pce.2016.10.011
  • Impact of salinity and Pb on enzyme activities of a saline soil from the
           Yellow River delta: A microcosm study
    • Authors: Lidi Zheng; Mingxiang Zhang; Rong Xiao; Jingxiao Chen; Feihai Yu
      Abstract: Publication date: Available online 11 November 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Lidi Zheng, Mingxiang Zhang, Rong Xiao, Jingxiao Chen, Feihai Yu
      Soil enzyme activities are sensitive to the changes of soil properties and pollutants. In this study, the influence of salinity and Pb on the soil enzyme (catalase, CAT; invertase, IA; urease, UA) activities regarding the soil aggregate size classes was investigated. We selected a saline soil from the Yellow River delta, and adopted an orthogonal experiment designed with five Pb concentration levels and five salinity levels. The soil was dry sieved into three soil aggregate size classes: >2000 μm, 250–2000 μm, and <250 μm. All three enzyme activities significantly decreased with the increase of soil salinity (P < 0.05). Pb had an inhibition effect on IA and UA activities but a significant promoting effect on CAT activity (P < 0.05) within the concentration range of 0–400 mg kg−1. When Pb concentration exceeded 400 mg kg−1, with the increase of Pb concentration, there were no significant changes of all the enzyme activities under the inhibition or promotion effects of Pb. The Pb concentration which leads to a significant reduction is between 0 and 200 mg kg−1 for IA activity and 200–400 mg kg−1 for UA activity. And the increase of soil salinity led to a higher toxicity of Pb for UA activity. The toxicity range could be a valid reference for the formulation of soil quality standards in estuarine wetlands. We concluded that the effects of Pb on soil enzyme activities depend on the Pb concentration, soil salinity and the enzyme types. IA activity showed a higher activity in the macro-aggregate (250–2000 μm), while there was no significant difference in CAT and UA activities among three particle size classes. Since the IA activity was sensitive to soil salinity, Pb concentration and soil aggregate size, it could be selected as a representative indicator for soil monitoring in the Yellow River delta.

      PubDate: 2016-11-13T15:32:01Z
      DOI: 10.1016/j.pce.2016.11.001
  • Modelling phytoremediation of nitrogen-polluted water using water hyacinth
           (Eichhornia crassipes)
    • Authors: Aloyce W. Mayo; Emmanuel E. Hanai
      Abstract: Publication date: Available online 30 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Aloyce W. Mayo, Emmanuel E. Hanai
      Water hyacinth (Eichhornia crassipes) has a great potential for purification of wastewater through physical, chemical and biological mechanisms. In an attempt to improve the quality of effluents discharged from waste stabilization ponds at the University of Dar es Salaam, a pilot plant was constructed to experiment the effectiveness of this plants for transformation and removal of nitrogen. Samples of wastewater were collected and examined for water quality parameters, including pH, temperature, dissolved oxygen, and various forms of nitrogen, which were used as input parameters in a kinetic mathematical model. A conceptual model was then developed to model various processes in the system using STELLA 6.0.1 software. The results show that total nitrogen was removed by 63.9%. Denitrification contributed 73.8% of the removed nitrogen. Other dominant nitrogen removal mechanisms are net sedimentation and uptake by water hyacinth, which contributed 16.7% and 9.5% of the removed nitrogen, respectively. The model indicated that in presence of water hyacinth biofilm about 1.26 g Nm-2day-1 of nitrogen was removed. However, in the absence of biofilm in water hyacinth pond, the permanent nitrogen removal was only 0.89 g Nm-2day-1. This suggests that in absence of water hyacinth, the efficiency of nitrogen removal would decrease by 29.4%.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.10.016
  • Development of probabilistic operating rules for Hluhluwe Dam, South
    • Authors: J. Ndiritu; J. Odiyo; R. Makungo; B. Mwaka; N. Mthethwa; C. Ntuli; A. Andanje
      Abstract: Publication date: Available online 30 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): J. Ndiritu, J. Odiyo, R. Makungo, B. Mwaka, N. Mthethwa, C. Ntuli, A. Andanje
      Hluhluwe Dam, with a 30 million m3 reservoir that supplies water for irrigation and Hluhluwe municipality in Kwa-Zulu Natal Province, South Africa, was consistently experiencing low storage levels over several non-drought years since 2001. The dam was operated by rules of thumb and there were no records of water releases for irrigation - the main user of the dam. This paper describes an assessment of the historic behaviour of the reservoir since its completion in 1964 and the development of operating rules that accounted for: i) the multiple and different levels of reliability at which municipal and irrigation demands need to be supplied, and ii) inter-annual and inter-decadal variability of climate and inflows into the dam. The assessment of the behaviour of the reservoir was done by simulation assuming trigonometric rule curves that were optimized to maximize both yield and storage state using the SCE-UA method. The resulting reservoir behaviour matched the observed historic trajectory reasonably well and indicated that the dam has mainly been operated at a demand of 10 million m3/year until 2000 when the demand suddenly rose to 25 million m3/year. Operating rules were developed from a statistical analysis of the base yields from 500 simulations of the reservoir each using 5 year-long stochastically generated sequences of inflows, rainfall and evaporation. After the implementation of the operating rules in 2009, the storage state of the dam improved and matched those of other reservoirs in the region that had established operating rules.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.10.017
  • Electrospun polyacrylonitrile nanofibers functionalized with EDTA for
           adsorption of ionic dyes
    • Authors: E.F.C. Chaúque; J.C. Ngila; Adedeji A. Adelodun; C.J. Greyling; L.N. Dlamini
      Abstract: Publication date: Available online 1 November 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): E.F.C. Chaúque, J.C. Ngila, Adedeji A. Adelodun, C.J. Greyling, L.N. Dlamini
      The manipulation of nanofibers’ surface chemistry could enhance their potential application toward the removal of ionic dyes in wastewater. For this purpose, surface modification of electrospun polyacrylonitrile (PAN) nanofibers with ethylenediaminetetraacetic acid (EDTA) and ethylenediamine (EDA) crosslinker was experimented. The functionalized EDTA-EDA-PAN nanofibers were characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) technique. The impregnation of EDA and EDTA chelating agents on the surface of PAN changed the distribution of nanofibers as proximity is increased (accompanied by reduced softness), but the nanofibrous structure of the pristine PAN nanofibers was not substantially altered. Adsorption equilibrium studies were performed with Freundlich, Langmuir and Temkin isotherm models with the former providing better correlation to the experimental data. The modified PAN nanofibers showed efficient sorption of methyl orange (MO) and reactive red (RR) from aqueous synthetic samples, evinced by the maximum adsorption capacities (at 25 ºC) of 99.15 and 110.0 mg g-1, respectively. The fabricated nanofibers showed appreciable removal efficiency of the target dye sorptives from wastewater. However, the presence of high metal ions content affected the overall extraction of dyes from wastewater due to the depletion of the adsorbent´s active adsorptive sites.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.10.008
  • H/V measurements as an effective tool for the reliable detection of
           landslide slip surfaces: Case studies of Castagnola (La Spezia, Italy) and
           Roccalbegna (Grosseto, Italy)
    • Authors: Veronica Pazzi; Luca Tanteri; Gabriele Bicocchi; Michele D'Ambrosio; Andrea Caselli; Riccardo Fanti
      Abstract: Publication date: Available online 25 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Veronica Pazzi, Luca Tanteri, Gabriele Bicocchi, Michele D'Ambrosio, Andrea Caselli, Riccardo Fanti
      A variety of methods (detailed geomorphological surveys, geotechnical investigations, local instrumentation, satellite data, and radar interferometry) along with geophysical techniques may be used to investigate slope instabilities and to detect the inhomogeneities of materials as well as their properties, boundaries, and sliding surfaces. Of these techniques, the method based on seismic noise measurements allows abrupt changes in seismic impedance at landslide boundaries resulting from varying levels of seismic velocity and material density to be detected. Peaks of the Horizontal to Vertical Spectral Ratio have proven to serve as effective indicators of the resonance frequency of low-impedance surface layers. In this work, horizontal to vertical spectral ratio surveys of the Castagnola (La Spezia, Italy) and Roccalbegna (Grosseto, Italy) landslides were carried out. From roughly 100 single-station measurements made inside and outside the landslides at each site, we define a threshold number of single-station seismic noise measures beyond which information is redundant because the variation in reconstructed impedance contrast surfaces is not significant. This approach allows one to reliably retrieve the geometry of a landslide body, ultimately generating useful information for determining whether further measurements are needed to improve landslide body reconstruction.

      PubDate: 2016-10-30T14:59:47Z
      DOI: 10.1016/j.pce.2016.10.014
  • A multidisciplinary approach to the seismic characterization of a mountain
           top (Monteluco, central Italy)
    • Authors: F. Durante; G. Di Giulio; M. Tallini; G. Milana; L. Macerola
      Abstract: Publication date: Available online 25 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): F. Durante, G. Di Giulio, M. Tallini, G. Milana, L. Macerola
      This study provides a seismic characterization of the flat top area of Monteluco carbonate mountain using a multidisciplinary approach. Recordings of ambient vibrations and local earthquakes, geophysical and borehole data, detailed geological surveys and rock mass characterizations were used to investigate the ground-motion amplification observed on the flat top of Monteluco. Weak motion measurements carried out on the top area gave resonance frequency (f0) in the range of 2–4 Hz, likely due to the occurrence of fractured rocks, tens of meters thick. In this frequency range and in the same target area, it was also possible to observe a nearly NW-SE polarization of the seismic signal, which we have tentatively correlated with the main mapped fault systems. Nevertheless, a topographic effect on noise polarization cannot be excluded.

      PubDate: 2016-10-30T14:59:47Z
      DOI: 10.1016/j.pce.2016.10.015
  • Results from shallow geophysical investigations in the northwestern sector
           of the island of Malta
    • Authors: M. Pischiutta; F. Villani; S. D’Amico; M. Vassallo; F. Cara; D. Di Naccio; D. Farrugia; G. Di Giulio; S. Amoroso; L. Cantore; A. Mercuri; D. Famiani; P. Galea; A. Akinci; A. Rovelli
      Abstract: Publication date: Available online 25 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M. Pischiutta, F. Villani, S. D’Amico, M. Vassallo, F. Cara, D. Di Naccio, D. Farrugia, G. Di Giulio, S. Amoroso, L. Cantore, A. Mercuri, D. Famiani, P. Galea, A. Akinci, A. Rovelli
      We performed geophysical investigations in the northwestern sector of the island of Malta to reconstruct velocity-depth models and provide shear-wave velocity profiles. We have chosen two sites, one located in Rabat (Malta) and another in the Golden Bay area. We used both active (seismic and electrical 2D-tomography, Multichanel Analysis of Surface Waves – MASW) and passive (2D arrays and single-station measurements using ambient noise) geophysical methods. Consistently with previous studies performed in this part of Malta, we have found that both sites are characterised by site resonance in the frequency range 1-2 Hz as an effect of the local lithostratigraphic succession that shows an impedance contrast at about 60-90 m depth. This resonance effect can have important implications on both seismic hazard as well as seismic risk evaluation of the region since the amplified frequency range coincides with the resonance frequencies typical of 5–10 storey buildings which are very diffuse in the Maltese Islands, especially after intense recent urbanization. We also highlight the importance of performing seismic velocity measurements even at rock sites. As an example, the Golden Bay site would be classified as class “A” following the EuroCode EC8 when considering only the outcropping lithology represented by limestone rocks. Conversely the subsoil characterization provided by this study has revealed that this site falls in the EC8 class “B”, stressing the importance of direct geophysical measurements since the a-priori assignment to A-class could lead to wrong estimates in evaluating the site response.

      PubDate: 2016-10-30T14:59:47Z
      DOI: 10.1016/j.pce.2016.10.013
  • The Effects of Material Loading and Flow Rate on the Disinfection of
           Pathogenic Microorganisms Using Cation Resin-Silver Nanoparticle Filter
    • Authors: L. Mpenyana-Monyatsi; N.H. Mthombeni; M.S. Onyango; M.N.B. Momba
      Abstract: Publication date: Available online 21 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): L. Mpenyana-Monyatsi, N.H. Mthombeni, M.S. Onyango, M.N.B. Momba
      Waterborne diseases have a negative impact on public health in instances where the available drinking water is of a poor quality. Decentralised systems are needed to provide safe drinking water to rural communities. Therefore, the present study aimed to develop and investigate the point-of-use (POU) water treatment filter packed with resin-coated silver nanoparticles. The filter performance was evaluated by investigating the effects of various bed masses (10 g, 15 g, 20 g) and flow rates (2 mL/min, 5mL/min, 10 mL/min) by means of breakthrough curves for the removal efficiency of presumptive Escherichia coli, Shigella dysenteriae, Salmonella typhimurium and Vibrio cholerae from spiked groundwater samples. The results revealed that, as the bed mass increases the breakthrough time also increases with regards to all targeted microorganisms. However, when the flow rate increases the breakthrough time decreased. These tests demonstrated that resin-coated silver nanoparticle can be an effective material in removing all targeted microorganisms at 100 % removal efficiency before breakthrough points are achieved. Moreover the filter system demonstrated that it is capable of producing 15 L/day of treated water at an operating condition of 10 mL/min flow rate and 15g bed mass, which is sufficient to provide for seven individuals in the household if they consume 2 L/person/day for drinking purpose. Therefore, the bed mass of the filter system should be increased in order for it to produce sufficient water that will conform to the daily needs of an individual.

      PubDate: 2016-10-23T18:25:56Z
      DOI: 10.1016/j.pce.2016.10.012
  • Development of a Silicone-membrane Passive Sampler for Monitoring
           Cylindrospermopsin and Microcystin LR-YR-RR in Natural Waters
    • Authors: Hlengilizwe Nyoni; Bhekie B. Mamba; Titus A.M. Msagati
      Abstract: Publication date: Available online 21 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Hlengilizwe Nyoni, Bhekie B. Mamba, Titus A.M. Msagati
      Silicone membrane tubes were functionalised by filling them with synthesised γ-Fe2O3 nanoparticles and used as a passive sampling device for monitoring microcystins and cylindrospermopsin in aquatic environments. This novel device was calibrated for the measurement of microcystin and cylindrospermopsin concentrations in water. The effect of temperature and hydrodynamics on the sampler performance was studied in a flow-through system under controlled conditions. The chemical uptake of microcystins (MCs) and cylindrospermopsin (CYN) into the passive sampler remained linear and integrative throughout the exposure period. The rate of accumulation of most of the MC compounds tested was dependent on temperature and flow velocity. The use of 13C labelled polychlorinated biphenyls as performance reference compounds (PRCs) in silicone membrane/γ-Fe2O3 nanoparticle passive sampler, Chemcatcher and polar organic chemical integrative sampler (POCIS) was evaluated. The majority of PRCs improved the semi quantitative nature of water concentration estimated by the three samplers. The corrected sampling rate values of model biotoxin compounds were used to estimate the time-weighted average concentrations in natural cyanobacterial water blooms of the Hartbeespoort dam. The corrected sampling rates R Scorr values varied from 0.1140 to 0.5628 Ld-1 between samplers with silicone membrane having the least R Scorr values compared to the Chemcatcher and POCIS. The three passive sampling devises provided a more relevant picture of the biotoxin concentration in the Hartbeespoort dam. The results suggested that the three sampling devices are suitable for use in monitoring microcystins and cylindrospermopsin concentrations in aquatic environments.

      PubDate: 2016-10-23T18:25:56Z
      DOI: 10.1016/j.pce.2016.10.010
  • Economic accounting of water: The Botswana experience
    • Authors: T. Setlhogile; J. Arntzen; O.B. Pule
      Abstract: Publication date: Available online 10 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): T. Setlhogile, J. Arntzen, O.B. Pule
      Water accounts aim to capture the value of water resources and their use within the economy. The accounts complement the National Accounts as the latter's main indicator (GDP) does not reflect changes in natural capital. Botswana developed water accounts for the period 2010/11–2014/15 using the UN's standard System of Environmental Economic Accounting for water (SEEA-water). The article focuses both on the construction of physical flow accounts as well as on the policy implications for development planning and water resource management through the use of policy indicators. It also shows long-term trends in water abstraction and water use efficiency linking the SEEA water accounts with results of earlier (non-SEEA) water accounting projects in Botswana. The water accounts results show that water abstraction and consumption have been largely stable since 2010/11 despite population (1.9% p.a.) and economic growth (around 5% p.a.) likely due to a combination of water sector reforms and drought conditions in south eastern Botswana; the latter led to the drying up of several dams and the imposition of severe water restrictions. While public attention focuses mostly on water service providers, self-providers (mines and the agricultural sector) account for more than 50% of total water abstracted from the environment of water, demonstrating the need to pay more attention to self-providers in IWRM implementation. Water consumption is highest for the agricultural sector (70.2 Mm3) followed by households and mines at 41.2 and 39 Mm3 respectively in 2014/15. In terms of water use efficiency, value added per m3 has increased in time, showing (some) decoupling of water consumption and economic growth. This positive trend needs to be enhanced in the pursuit of economic diversification, which should focus on growth of water-efficient economic sectors. Finally, per capita water consumption has decreased over time; while this may indicate that people conserve water, it may also point at delivery problems associated with water sector reforms. This requires further analysis.

      PubDate: 2016-10-17T02:34:10Z
      DOI: 10.1016/j.pce.2016.10.007
  • Generation of climate change scenarios for precipitation and temperature
           at local scales using SDSM in Wami-Ruvu river basin Tanzania
    • Authors: Metekiya M. Gulacha; Deogratias M.M. Mulungu
      Abstract: Publication date: Available online 8 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Metekiya M. Gulacha, Deogratias M.M. Mulungu
      The Wami-Ruvu River Basin is important for socio-economic activities in country such as water supply for Dar es Salaam and Morogoro cities, and major agricultural activities such as sugarcane irrigation at Mtibwa and Bagamoyo. Due to projected climate change and its impacts at global scale, it is important to understand future climate change impacts on water resources of Wami-Ruvu River basin. Rainfall and temeparature are key variables for analysis of water resources and were used in this study. The statistical downscaling model (SDSM) was used to downscale the coarse global circulation model (GCM) to local scales by involving predictor predictand relationship. The predictor variables were selected based on partial correlation value (partial r) and significance value (p-value). For assessment of climate change, the baseline period was 30 years during 1961-1990. The baseline period was partitioned into two periods for SDSM calibration and validation: 1961-1975 and 1976-1990 respectively. In this case, ground stations and the U.S. National Center for Environmental Prediction (NCEP) reanalysis atmospheric data were used. During validation, the inbuilt scenario generator was used to generate simulated time series for five stations: Morogoro Maji, Ulaya, Ukaguru, Morogoro Airport, Dodoma Airport and Ruvu at Morogoro Rd. Brd. For precipitation, the SDSM’s R2 (-) for the two periods ranged 0.07 - 0.20 and 0.21 - 0.63 respectively. The respective coefficient of correlation, r (-) ranged 0.03 - 0.05 and 0.46 - 0.80, indicating low to high performance of the SDSM. The respective R2 (-) values for temperature ranged: 0.42 – 0.5 and 0.6 – 0.98 respectively. The calibrated SDSM model was then used to downscale Global Circulation Model (GCM) scenario data to the local scales. The GCM used was HadCM3 where A2 and B2 scenarios were used. The climate change scenarios were determined using change factors. Results showed that for Wami-Ruvu basin the mean rainfall will change by -44-107%, -69-328% and 68-648% during 2020s, 2050s and 2080s for A2 scenario while by -37-117%, -56-199 and -76-346% respectively for B2 scenario as compared to the baseline period. In all cases, Ulaya and Morogoro Maji stations presented the lowest and highest extremes in the ranges. The downscaled and projected average monthly maximum temperature indicated increasing trend from 0.2 to 7.5 oC in 2020s to 2080s time period. The minimum temperature showed decreasing trend from -0.4 to -1.5oC during the same periods. These results indicate potential for floods or droughts occurrence in the basin, accordingly adaptation measures will be necessary.

      PubDate: 2016-10-10T01:55:52Z
      DOI: 10.1016/j.pce.2016.10.003
  • Assessing and mapping the severity of soil erosion using the 30-m Landsat
           multispectral satellite data in the former South African homelands of
    • Authors: Khoboso Seutloali; Timothy Dube; Onisimo Mutanga
      Abstract: Publication date: Available online 4 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Khoboso Seutloali, Timothy Dube, Onisimo Mutanga
      Soil erosion is increasingly recognised as the principal cause of land degradation, loss of agricultural land area and siltation of surrounding water waterbodies. Accurate and up-to-date soil erosion mapping is key in understanding its severity if these negative impacts are to be minimised and affected areas rehabilitated. The aim of this work was to investigate map the severity of soil erosion, based on the 30-m Landsat series multispectral satellite data in the former South African homelands of Transkei between the year 1994 and 2010. Further, the study assessed if the observed soil erosion trends and morphology that existed in this area could be explained by biophysical factors (i.e. slope, stream erosivity, topographic wetness index) retrieved from the 30-m ASTER Digital Elevation Model (DEM). The results of this study indicate that the Transkei region experience varying erosion levels from moderate to very `severe. The large portion of the land area under the former homelands was largely affected by rill erosion with approximately 74% occurring in the year 1984 and 54% in 2010. The results also revealed specific thresholds of soil erosion drivers. These include steeper areas (≥30°), high stream power index greater than 2.0 (stream erosivity), relatively lower vegetation cover (≤15%) and low topographic wetness index (≤5%). The results of this work demonstrate the severity of soil erosion in the Southern African former homelands of Transkei for the year 1984 and 2010. Additionally, this work has demonstrated the significance of the 30-m Landsat multispectral sensor in examining soil erosion occurrence at a regional scale where in depth field work still remain a challenging task.

      PubDate: 2016-10-10T01:55:52Z
      DOI: 10.1016/j.pce.2016.10.001
  • Chitosan-based nanocomposites for de-nitrification of water
    • Authors: Monaheng L. Masheane; Lebea N. Nthunya; Soraya P. Malinga; Edward N. Nxumalo; Sabelo D. Mhlanga
      Abstract: Publication date: Available online 4 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Monaheng L. Masheane, Lebea N. Nthunya, Soraya P. Malinga, Edward N. Nxumalo, Sabelo D. Mhlanga
      Novel chitosan (CTs) nanocomposite beads containing alumina (Al2O3, denoted as Al in the nanocomposites) and functionalized multiwalled carbon nanotubes (f-MWCNTs) (CTsAl/f-MWCNTs) were prepared using an environmentally benign phase inversion method and subsequently used for the removal of nitrates (NO3 -) in water. The ellipsoidal beads with an average size of 3 mm were readily formed at room temperature and contained a small amount of Al (20 wt%) and f-MWCNTs (5%). The beads were found to adsorb nitrates effectively over a wide range of pH (pH 2 – pH 6) and showed maximum nitrates removal of 96.8% from a 50 mg/L nitrate water solution. Pure CTs beads on the other hand removed only 23% at pH 4. Kinetic studies suggested that the particle diffusion was rate controlling step for the adsorption of nitrates on CTsAl/f-MWCNT nanocomposite beads. Langmuir-Freundlich isotherms revealed that the adsorption of nitrates was on the heterogeneous surface of CTsAl/f-MWCNT beads. The Dubinin–Radushkevich (D-R) isotherm further revealed that the adsorption of nitrates was by electrostatic interaction. Thermodynamic studies suggested that the adsorption was spontaneous and exothermic. More than 70% recovery was achieved for 5 cycles of desorption-degeneration studies. Al and f-MWCNTs have shown to improve swelling and solubility of CTs.

      PubDate: 2016-10-10T01:55:52Z
      DOI: 10.1016/j.pce.2016.10.004
  • Assessment of Drinking Water Quality and Rural Household Water Treatment
           in Balaka District, Malawi
    • Authors: Raphael C. Mkwate; Russel C.G. Chidya; Elijah M.M. Wanda
      Abstract: Publication date: Available online 6 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Raphael C. Mkwate, Russel C.G. Chidya, Elijah M.M. Wanda
      Access to drinking water from unsafe sources is widespread amongst communities in rural areas such as Balaka District in Malawi. This situation puts many individuals and communities at risk of waterborne diseases despite some households adopting household water treatment to improve the quality of the water. However, there still remains data gaps regarding the quality of drinking water from such sources and the household water treatment methods used to improve public health. This study was, therefore, conducted to help bridge the knowledge gap by evaluating drinking water quality and adoption rate of household water treatment and storage (HWTS) practices in Nkaya, Balaka District. Water samples were collected from eleven systematically selected sites and analyzed for physico-chemical and microbiological parameters: pH, TDS, electrical conductivity (EC), turbidity, F-, Cl-, NO3 -, Na, K, Fe, Faecal Coliform (FC) and Faecal Streptococcus (FS) bacteria using standard methods. The mean results were compared to the World Health Organization (WHO) and Malawi Bureau of Standards (MBS) (MS 733:2005) to ascertain the water quality for drinking purposes. A total of 204 randomly selected households were interviewed to determine their access to drinking water, water quality perception and HWTS among others. The majority of households (72%, n=83) in Njerenje accessed water from shallow wells and rivers whilst in Phimbi boreholes were commonly used. The majority of household (>95%, n=204) were observed to be practicing HWST techniques by boiling or chlorination and water storage in closed containers. The levels of pH (7.10-7.64), F- (0.89-1.46 mg/L), Cl- (5.45-89.84 mg/L), NO3 - (0-0.16 mg/L), Na (20-490 mg/L), K (2.40-14 mg/L) and Fe (0.10-0.40 mg/L) for most sites were within the standard limits. The EC (358-2220 μS/cm), turbidity (0.54-14.60 NTU), FC (0-56 cfu/100 mL) and FS (0-120 cfu/100 mL) - mainly in shallow wells, were found to be above the WHO and MBS water quality specifications. The majority of the water samples (73%, n=11) were classified as of “Intermediate risk” (FC 11-100 cfu/100 mL), hence not suitable for human consumption without prior treatment. This calls for large scale adoption of HWTS and continued monitoring of the water sources used in the study areas.

      PubDate: 2016-10-10T01:55:52Z
      DOI: 10.1016/j.pce.2016.10.006
  • Managing water supply systems using free-market economy approaches: A
           detailed review of the implications for developing countries
    • Authors: C. Chikozho; K. Kujinga
      Abstract: Publication date: Available online 4 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): C. Chikozho, K. Kujinga
      Decision makers in developing countries are often confronted by difficult choices regarding the selection and deployment of appropriate water supply governance regimes that sufficiently take into account national socio-economic and political realities. Indeed, scholars and practitioners alike continue to grapple with the need to create the optimum water supply and allocation decision-making space applicable to specific developing countries. In this paper, we review documented case studies from various parts of the world to explore the utility of free-market economics approaches in water supply governance. This is one of the major paradigms that have emerged in the face of enduring questions regarding how best to govern water supply systems in developing countries. In the paper, we postulate that increasing pressure on available natural resources may have already rendered obsolete some of the water supply governance regimes that have served human societies very well for many decades. Our main findings show that national and municipal water supply governance paradigms tend to change in tandem with emerging national development frameworks and priorities. While many developing countries have adopted water management and governance policy prescriptions from the international arena, national and local socio-economic and political realities ultimately determine what works and what does not work on the ground. We thus, conclude that the choice of what constitutes an appropriate water supply governance regime in context is never simple. Indeed, the majority of case studies reviewed in the paper tend to rely on a mix of market economics and developmental statism to make their water governance regimes more realistic and workable on the ground.

      PubDate: 2016-10-10T01:55:52Z
      DOI: 10.1016/j.pce.2016.10.002
  • Effect of monthly areal rainfall uncertainty on streamflow simulation
    • Authors: J.G. Ndiritu; N. Mkhize
      Abstract: Publication date: Available online 4 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): J.G. Ndiritu, N. Mkhize
      Areal rainfall is mostly obtained from point rainfall measurements that are sparsely located and several studies have shown that this results in large areal rainfall uncertainties at the daily time step. However, water resources assessment is often carried out a monthly time step and streamflow simulation is usually an essential component of this assessment. This study set out to quantify monthly areal rainfall uncertainties and assess their effect on streamflow simulation. This was achieved by; i) quantifying areal rainfall uncertainties and using these to generate stochastic monthly areal rainfalls, and ii) finding out how the quality of monthly streamflow simulation and streamflow variability change if stochastic areal rainfalls are used instead of historic areal rainfalls. Tests on monthly rainfall uncertainty were carried out using data from two South African catchments while streamflow simulation was confined to one of them. A non-parametric model that had been applied at a daily time step was used for stochastic areal rainfall generation and the Pitman catchment model calibrated using the SCE-UA optimizer was used for streamflow simulation. 100 randomly-initialised calibration-validation runs using 100 stochastic areal rainfalls were compared with 100 runs obtained using the single historic areal rainfall series. By using 4 rain gauges alternately to obtain areal rainfall, the resulting differences in areal rainfall averaged to 20% of the mean monthly areal rainfall and rainfall uncertainty was therefore highly significant. Pitman model simulations obtained coefficient of efficiencies averaging 0.66 and 0.64 in calibration and validation using historic rainfalls while the respective values using stochastic areal rainfalls were 0.59 and 0.57. Average bias was less than 5% in all cases. The streamflow ranges using historic rainfalls averaged to 29% of the mean naturalized flow in calibration and validation and the respective average ranges using stochastic monthly rainfalls were 86 and 90% of the mean naturalised streamflow. In calibration, 33% of the naturalized flow located within the streamflow ranges with historic rainfall simulations and using stochastic rainfalls increased this to 66%. In validation the respective percentages of naturalised flows located within the simulated streamflow ranges were 32 and 72% respectively. The analysis reveals that monthly areal rainfall uncertainty is significant and incorporating it into streamflow simulation would add validity to the results.

      PubDate: 2016-10-10T01:55:52Z
      DOI: 10.1016/j.pce.2016.10.005
  • Profiles of innovators in a semi-arid smallholder agricultural environment
           in south west Zimbabwe
    • Authors: Eness P. Mutsvangwa-Sammie; Emmanuel Manzungu; Shephard Siziba
      Abstract: Publication date: Available online 21 September 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Eness P. Mutsvangwa-Sammie, Emmanuel Manzungu, Shephard Siziba
      Innovations are regarded as critical to improving the efficiency, productivity and effectiveness of African agriculture. However, few efforts have been directed at understanding ‘agricultural innovators’, especially among smallholder farmers in sub-Saharan Africa who face low agricultural productivity and widespread food insecurity. This paper investigates the profile of innovators from a local perspective in a semi-arid smallholder farming area in south-west Zimbabwe. The paper is based on data collected from key informant interviews and a household questionnaire survey administered to 239 households from Gwanda and Insiza districts between 2013 and 2014. Qualities or attributes of an innovator (which constitute the profile of an innovator) identified by key informants included: resource endowment; social networks; education; and enthusiasm (passionate and hardworking). The attributes were used in a logit regression model to estimate the probability of the 239 households exhibiting the attributes of an innovator. Social networks and resource endowment, as depicted by amount of land cultivated, were found to significantly influence the probability of an individual being an innovator. Interestingly, the common attributes of education or belonging to an innovation platform used by extension and development agents, were found not to influence the probability of one being an innovator. The paper concludes that understanding local perceptions of innovators, which is based on appreciation of the socio-economic and biophysical circumstances, should be used to identify a ‘basket’ of context specific innovations that have potential to address the diverse needs of rural households farming households.

      PubDate: 2016-09-26T00:50:58Z
      DOI: 10.1016/j.pce.2016.09.002
  • 3rd International Conference on Ecohydrology, Soil and Climate Change,
    • Authors: Cristina Andrade; Samantha Hughes Santos
      Abstract: Publication date: August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 94
      Author(s): Cristina Andrade, Samantha Hughes, João A. Santos

      PubDate: 2016-09-21T00:30:57Z
  • A comparative analysis of site-specific response spectral amplification
    • Authors: Valerio Poggi; Benjamin Edwards; Donat Fäh
      Abstract: Publication date: Available online 16 September 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Valerio Poggi, Benjamin Edwards, Donat Fäh
      In the framework of the Seismic Hazard Harmonization in Europe (SHARE) project, the Swiss Seismological Service (SED) has performed an evaluation of two procedures developed to produce soil amplification models for 5% damped pseudo-spectral acceleration response spectra, each using different parameters to describe the soil properties. The goal of the work presented here is to evaluate the statistical consistency of the methods, with particular regard to their applicability to engineering practice. Additionally, we compare the results with those from a methodology internally developed by the SED, which is based on spectral modeling of ground motion using the quarter-wavelength approximation to parameterize soil conditions. Soil amplification is computed with respect to reference rock condition as defined for the probabilistic seismic hazard assessment performed during the SHARE project. For the comparison, a residual analysis was performed between the computed soil-amplification functions from the three different methodologies, over a number of selected sites spanning different soil classes and ground motion levels. The analysis of the average residuals of these functions is useful to highlight the main differences between the proposed approaches, with special regard to the impact of soil resonances and anelastic attenuation within different frequency bands. The assessment was performed on a group of 88 selected stations of the Japanese KiKNet strong-motion network, for which complete logs of the shear-wave velocity profiles are available, in addition to a significant number of earthquake recordings. In a first step, average residuals were computed. Subsequently, amplification variability related to soil classes was investigated. The target of this second step was to perform the comparison by separately analyzing the impact of different soil and velocity classes, according to a soil-classification scheme proposed by Aristotle University of Thessaloniki (AUTH). In this paper the main results of these investigations are summarized and, when applicable, an interpretation of our findings is given.

      PubDate: 2016-09-21T00:30:57Z
      DOI: 10.1016/j.pce.2016.09.001
  • Modelling analysis of water-use efficiency of Maize in Heihe river basin
    • Authors: Guofeng Wang; Jiancheng Chen; Qing Zhou; Xi Chu; Xiaoxue Zhou
      Abstract: Publication date: Available online 6 September 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Guofeng Wang, Jiancheng Chen, Qing Zhou, Xi Chu, Xiaoxue Zhou

      PubDate: 2016-09-08T13:56:03Z
      DOI: 10.1016/j.pce.2016.08.010
  • Water Ecological Function Zoning in Heihe River Basin, Northwest China
    • Authors: Dongdong Chen; Gui Jin; Qian Zhang; Aisha Olushola Arowolo; Yifan Li
      Abstract: Publication date: Available online 7 September 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Dongdong Chen, Gui Jin, Qian Zhang, Aisha Olushola Arowolo, Yifan Li
      Rapid urbanization coupled with increase in population growth rate in recent years has accelerated economic pressure on the ecological environment leading to a gradual deterioration of global and regional environment. This has particularly resulted into water contamination and shortage of water resources thus posing a great threat to human survival. How to guaranteeing sustainable use of basin water resources has attracted more and more attentions. The Heihe River Basin is the secondary longest river inland China and the significantly water source of Hexi Corridor, the problem of water pollution, ecological environment deterioration and the shortage of water has seriously threatened the ecological system of the Heihe River Basin. In this study, through depicting the characteristics of natural environment, human activities, water ecosystem services and other factors in Heihe River Basin we delineated the water ecological function in Heihe River using the principal components analysis and the K-means clustering method. In the study, Heihe river Basin is divided into 3 primary level areas and 8 secondary level sub-areas. Water ecological characteristics analysis showed that the spatial distribution of the water ecological function of Heihe River Basin was not uniform, which are mainly showed in three aspects, function of windproof and sand fixation, function of soil erosion prevention and function of water sources conservation. The results of this study can provide effective and scientific theoretical references for the integrated water sources management and the ecological function optimization of the Heihe River Basin.

      PubDate: 2016-09-08T13:56:03Z
      DOI: 10.1016/j.pce.2016.08.005
  • Effects of salinity on dynamics of soil carbon in degraded coastal
           wetlands: implications on wetland restoration
    • Authors: Qingqing Zhao; Junhong Bai; Qiongqiong Lu; Guangliang Zhang
      Abstract: Publication date: Available online 30 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Qingqing Zhao, Junhong Bai, Qiongqiong Lu, Guangliang Zhang
      To investigate the effects of salinity on dynamics of soil carbon contents and stocks, soil samples were collected at a depth of 30 cm at four sampling sites (Sites B, T, S and P) along a salinity gradient in a drained coastal wetland, the Yellow River Delta, China. The salinity of these four sites ranked in the order: B (8.68 ± 4.25 ms/cm) > T (5.89 ± 3.17 ms/cm) > S (3.19 ± 1.01 ms/cm) > P (2.26 ± 0.39 ms/cm). Soil total carbon (TC), soil organic carbon (SOC), and soil microbial biomass carbon (MBC) were measured. Based on these data, soil organic carbon density (SOCD) and soil microbial biomass carbon density (MBCD) were calculated at four sites. The results showed that the mean concentrations of TC and MBC showed a general deceasing tendency with increasing salinities in the top 30 cm of soils. The values of SOCD and MBCD exhibited similar tendency along the salinity gradient. As for profile distribution pattern, The C/N ratios ranged from 8.28 to 56.51. The microbial quotient values at four sampling sites were quite low, ranging from 0.06-0.19. Higher C/N ratios were found in samples with high salinity. Correlation analysis showed that the concentrations of TC and MBC at four sampling sites were significantly negatively correlated with salinity (P < 0.01 or P < 0.05), indicating that salinity could inhibit soil carbon accumulation and microbial activities.

      PubDate: 2016-09-03T13:21:07Z
      DOI: 10.1016/j.pce.2016.08.008
  • A Method to Correct Eddy Covariance Flux Underestimates under an Advective
           Environment for Arid or Semi-arid Regions
    • Authors: Hongbo Su; Yongmin Yang; Lina Xu; José L. Chávez; Steven R. Evett; Terry A. Howell; Jing Tian; Shaohui Chen; Jinyan Zhan
      Abstract: Publication date: Available online 31 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Hongbo Su, Yongmin Yang, Lina Xu, José L. Chávez, Steven R. Evett, Terry A. Howell, Jing Tian, Shaohui Chen, Jinyan Zhan
      Water scarcity is one of the main factors limiting agricultural development in arid or semi-arid areas. Accurate Evapotranspiration (ET) observations and estimations are crucial in water cycle studies to estimate water losses from the terrestrial surfaces to the atmosphere to close the regional water budget. The eddy covariance (EC) method is an important technique measure ET and other land surface energy fluxes. However, the underestimation of energy fluxes and the problem of EC energy balance non-closure are far from solved. In this study, a new method is proposed to account for advection in order to correct EC data under advective environments. This advection based method was applied to data from Bushland, TX, which is subject to dry air and strong winds. Observations from two identical EC systems as well as two precision monolithic weighing lysimeters were used in this analysis. Both EC sites showed significant underestimates of evapotranspiration (ET) compared with lysimeter measurements. The daily energy balance closure for NE01 and SE02 sites were 0.78 and 0.74 respectively. The advection correction method provided improved performance in daytime, and it is more suitable for ET estimate than forcing closure under the advective environment. For nighttime, two methods (NCM1 and NCM2) were proposed to correct EC underestimates. Finally, all the corrected ET values were compared with the lysimeter measurements. For NE01 site, the MAD (mean absolute deviation) and the RMSD (root mean square deviation) were 47.72 W/m2 and 67.66 W/m2, respectively; and the r2 (coefficient of determination) was 0.85. For SE02 site, the MAD and RMSD were 30.59 W/m2 and 44.43 W/m2; and the r2 was 0.93. The statistical measures illustrated that the proposed methods are functional and appropriate under an advective environment. The accurate estimate of actual evapotranspiration will benefit both the strategic planning of optimal water uses and the improved understanding the environmental and hydrological processes.

      PubDate: 2016-09-03T13:21:07Z
      DOI: 10.1016/j.pce.2016.08.009
  • The 24 May 2014 (Mw6.8) earthquake (North Aegean Trough): spatiotemporal
           evolution, source and slip model from teleseismic data
    • Authors: Anastasia Kiratzi; Eva Tsakiroudi; Christoforos Benetatos; George Karakaisis
      Abstract: Publication date: Available online 28 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Anastasia Kiratzi, Eva Tsakiroudi, Christoforos Benetatos, George Karakaisis
      We use teleseismic data to calculate the source model of the 24 May 2014 earthquake and regional catalogues to examine the spatial-temporal characteristics of the sequence. The sequence started in Saros Basin but almost simultaneously aftershocks spread along a ∼200 km zone, activating the entire North Aegean Trough. The aftershock sequence was rich in moderate (M<4) size events, but very deficient in strong events – only two Mw4.9 aftershocks-a characteristic observed in previous sequences in the region. The teleseismic waveforms were best fit by two sub-events, which were lagged by 18s in time and by a 50 km jump in space, along the same fault line. The centroid depth of the first sub-event is 22km, at the base of the lower crust, and for the second is 14 km. The resolved total source time function is ∼30s. The finite-fault slip model is characterized by an asymmetric bilateral rupture propagation, to the west and east of the hypocentre. The major slip is confined downdip from the hypocentre, within the deeper 12-25km part. This deep slip migrated updip from the hypocentre to form the second slip patch, in the eastward segment. In all our models the maximum dislocation was of the order of 1m. For our preferred model parametrization, the rupture speed is 3km/s, and the scalar moment equal to 1.76×1019 Nm (Mw6.8). This earthquake highlighted the fact that strike-slip faulting in the North Aegean Sea, can attain large lengths and activate very wide zones, reaching densely populated regions.

      PubDate: 2016-08-29T12:34:54Z
      DOI: 10.1016/j.pce.2016.08.003
  • Electrospun and functionalized PVDF/PAN composite for the removal of trace
           metals in contaminated water
    • Authors: R.M. Nthumbi; A.A. Adelodun; J.C. Ngila
      Abstract: Publication date: Available online 29 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): R.M. Nthumbi, A.A. Adelodun, J.C. Ngila
      The electrospinning of a nanofiber composite of polyvinylidene fluoride (PVDF) and polyacrylonitrile (PAN) in a dimethylformamide (DMF) solvent was carried out prior to functionalization by free radical grafting of acrylic acid (AA) brushes. Subsequent application for the removal of Pb2+ and Cd2+ from contaminated water is reported. Free radicals were initiated on the polymeric nanofiber composite using 5% 2,2′-Azobis(2-methylpropionitrile) (AIBN) in acetone. Upon solvent removal by air-drying, AA was added and grafting (in a methanol-water solvent system) was carried out in an oil bath at 70 °C for 5 h under nitrogen atmosphere. Structural and chemical characterization of the composite was done using scanning electron microscope (SEM), nitrogen sorption at 77 K (BET method), goniometer and Fourier transform infrared spectrometer (FTIR), while changes in metal ion concentration during batch adsorption were monitored using inductively coupled plasma optical emission spectrometer (ICP-OES). Through isotherm study, the adsorption was confirmed to follow both Langmuir and Freundlich models whilst adsorption kinetic studies showed that the adsorption rate is of pseudo-second order. In furtherance, the respective values for adsorption capacity and estimated removal efficiency for Pb2+ and Cd2+ were 1.585 and 0.164 mg.g-1, 90% and 80% respectively, while a 5% loss in regeneration efficiency after 10 cycles was also observed. Consequently, the nanocomposite was found efficient when applied to the removal of Pb2+ and Cd2+ from contaminated water.

      PubDate: 2016-08-29T12:34:54Z
      DOI: 10.1016/j.pce.2016.08.007
  • When good practices by water committees are not relevant: sustainability
           of small water infrastructures in semi-arid mozambique
    • Authors: Raphaelle Ducrot
      Abstract: Publication date: Available online 24 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Raphaelle Ducrot
      This paper explores the contradiction between the need for large scale interventions in rural water supplies and the need for flexibility when providing support for community institutions, by investigating the implementation of the Mozambique - National Rural Water Supply and Sanitation Program in a semi-arid district of the Limpopo Basin. Our results showed that coordinated leadership by key committee members, and the level of village governance was more important for borehole sustainability than the normative functioning of the committee. In a context in which the centrality of leadership prevails over collective action the sustainability of rural water infrastructure derives from the ability of leaders to motivate the community to provide supplementary funding. This, in turn, depends on the added value to the community of the water points and on village politics. Any interventions that increased community conflicts, for example because of lack of transparency or unequitable access to the benefit of the intervention, weakened the coordination and the collective action capacity of the community and hence the sustainability of the infrastructures even if the intervention was not directly related to water access. These results stress the importance of the project/program implementation pathway.

      PubDate: 2016-08-25T12:16:25Z
  • Surface geology and morphologic effects on seismic site response: the
           study case of Lampedusa, Italy
    • Authors: F. Panzera; G. Lombardo; S. Sicali; S. D'Amico
      Abstract: Publication date: Available online 22 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): F. Panzera, G. Lombardo, S. Sicali, S. D’Amico
      A joint Italo-Maltese research project (Costituzione di un Sistema Integrato di Protezione Civile Transfrontaliero Italo-Maltese, SIMIT) was financially supported by the European community with the aim to produce hazard maps in the area between the south-eastern Sicilian coast and the Sicily Channel including the islands of Lampedusa and Malta. In the frame of this project, the present study investigates the characteristics of the local seismic response in Lampedusa, a carbonate shelf belonging to the foreland domain at the northern edge of the African plate. Ninety-two ambient noise recordings were collected and processed through spectral ratio techniques. Polarization of the horizontal component of motion was also investigated in order to set into evidence possible directional effects. Results point out that in the central part of the island, where the most ancient and rigid terrains outcrop most of the spectral ratio plots show no particular site effects. On the other hand, nearby morphologic escarpments and fault lines, pronounced spectral ratio peaks in the frequency range 2.0 – 5.0 Hz are observed. These peaks, as highlighted by polarization analysis, are clearly directional with the largest amplification occurring with high angle (60°-90°) to the structures strike. Moreover, in sites located close to recent and soft deposits outcrops other significant seismic site effects at frequency higher than 5.0 Hz are identified. We can however assert that, rather than the surface lithology, the presence of cliff areas and tectonic structures strongly influence the local amplification of the ground motion and the occurrence of directional effects.

      PubDate: 2016-08-25T12:16:25Z
      DOI: 10.1016/j.pce.2016.08.006
  • Polyethyleneimine-carbon nanotube polymeric nanocomposite adsorbents for
           the removal of Cr6+ from water
    • Authors: Shepherd S. Sambaza; Monaheng L. Masheane; Soraya P. Malinga; Edward N. Nxumalo; Sabelo D. Mhlanga
      Abstract: Publication date: Available online 17 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Shepherd S. Sambaza, Monaheng L. Masheane, Soraya P. Malinga, Edward N. Nxumalo, Sabelo D. Mhlanga
      This work reports on the synthesis of multi-walled carbon nanotubes (MWCNTs) and their use in branched polyethyleneimine-multiwalled carbon nanotube (PEI-MWCNT) polymeric nanocomposite adsorbents for the removal of Cr6+ from contaminated water. The nanostructured materials were characterized using TEM, Raman, FTIR, BET surface area and zeta potental measurements. TEM confirmed the average diameter of the MWCNTs to be 25 nm. The point of zero-charge of PEI was at pH 8 and that of PEI-MWCNTs was at pH 7.7. FTIR analysis confirmed the formation of a new bond (–C=O at 1716 cm-1) between the functional groups on the MWCNTs and PEI. Batch adsorption and kinetic studies showed that the PEI-MWCNT nanocomposite materials were more efficient in the removal of Cr6+ solution from water samples. The optimum conditions for adsorption were pH ≤ 4, contact time of 60 min. When the PEI-MWCNT dosage was increased the adsorption capacity increased. The kinetic adsorption data obtained for Cr6+ solution followed pseudo-second order model. The adsorption of Cr6+ solution reached equilibrium within 60 min of contact time with a removal of 99%. The adsorbents were effective even after 5 cycles of use.

      PubDate: 2016-08-19T11:42:33Z
      DOI: 10.1016/j.pce.2016.08.002
  • Reception conditions of low frequency (LF) transmitter signals onboard
           DEMETER micro-satellite
    • Authors: M.Y. Boudjada; P.F. Biagi; E. Al-Haddad; P.H.M. Galopeau; B. Besser; D. Wolbang; G. Prattes; H. Eichelberger; G. Stangl; M. Parrot; K. Schwingenschuh
      Abstract: Publication date: Available online 12 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M.Y. Boudjada, P.F. Biagi, E. Al-Haddad, P.H.M. Galopeau, B. Besser, D. Wolbang, G. Prattes, H. Eichelberger, G. Stangl, M. Parrot, K. Schwingenschuh
      We analyse the flux density variation associated to low frequency (LF) broadcasting transmitters observed by the ICE electric field experiment onboard DEMETER micro-satellite, observed from 01st Jan. to 09th Dec. 2010. We select five stations localised around the Mediterranean and the Black seas: Tipaza (252 kHz, 02°28’E, 36°33’N, Algeria), Roumoules (216 kHz, 06°08’E, 43°47’N, Monte Carlo), Polatli (180 kHz, 32°25’E, 39°45’N, Turkey), Nadour (171 kHz, 02°55’W, 35°02’N, Morocco) and Brasov (153 kHz, 25°36’E,45°40’, Romania). The detection of the LF transmitter signals by DEMETER micro-satellite is found to depend on the radiated power, the emitted frequency, and the orbit paths with regard to the location of the stations. This leads us to characterise the reception condition of the LF signals and to define time intervals where the detection probability is high. We show that LF signal are regularly recorded, each 12 days, when the satellite is above the broadcasting station. The signal intensity levels are principally significant during the solar activity. Hence we find that the solar and the geomagnetic activities are slightly correlated to the maxima of LF signal as recorded by DEMETER. Also we note a drop of the intensity level several days before the occurrence of earthquakes in/around the Mediterranean and Black seas.

      PubDate: 2016-08-15T11:36:45Z
      DOI: 10.1016/j.pce.2016.07.006
  • Forecast and optimal allocation of production, living and ecology water
           consumption in Zhangye, China
    • Authors: Qian Xu; Wei Song; Ying Zhang
      Abstract: Publication date: Available online 6 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Qian Xu, Wei Song, Ying Zhang
      The water crisis is one of three crises that are persecuting the world. China is among the countries that face severe water shortages. Water scarcity and water pollution have seriously affected China's sustainable development in terms of the economy and society. Water resources per capita of China is only one quarter of the world's average. In addition, about 70 percent of China’s rivers, lakes, and reservoirs are affected by pollution. Due to limited water resources, a crucial issue for the sustainable development of the watershed is how to resolve the human/nature competition for water and how to achieve the coordinated development of the economy, society and ecology. On the basis of defining water consumption for production, living and ecology (WPLE), this paper proposes a framework for forecasting and optimally allocating WPLE. Using Zhangye, in the middle reaches of the Heihe River Basin as the case study area, we forecasted and optimally allocated WPLE under three development scenarios, i.e. the conventional development scenario (CDS), the economy-priority development scenario (EPDS) and the environmentally sustainable development scenario (ESDS). In 2010, the proportions of WPLE in Zhangye were 87.73%, 2.74% and 9.53%, respectively. In 2020, the proportions of WPLE will be 74.80%, 4.50% and 20.70% under the CDS, 76.16%, 5.27% and 18.57% under the EPDS, and 74.99%, 4.51% and 20.50% under the ESDS. In the future, the proportion of production water consumption of Zhangye will drastically decrease, while the proportion of ecological water consumption will significantly increase. The main contradiction of the co-evolution of WPLE of Zhangye is the competitiveness of production and living water consumption with ecological water consumption.

      PubDate: 2016-08-10T11:13:00Z
      DOI: 10.1016/j.pce.2016.07.003
  • Site amplification at the city scale in Basel (Switzerland) from
           geophysical site characterization and spectral modelling of recorded
    • Authors: Clotaire Michel; Donat Fäh; Benjamin Edwards; Carlo Cauzzi
      Abstract: Publication date: Available online 6 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Clotaire Michel, Donat Fäh, Benjamin Edwards, Carlo Cauzzi
      Hazard assessment at the city scale requires a detailed characterization of the effect of surface geology on ground motion (site effects). Though this analysis is commonly achieved using geophysical site characterization and site response modelling, we propose here a complementary analysis based on amplification functions retrieved from Empirical Spectral Modelling (ESM) of earthquake recordings. We applied this method to the city of Basel (Switzerland) that benefits from a detailed microzonation and a dense Strong Motion Network with 21 modern free-field stations. We first verified the accuracy of ESM amplification functions for this region and used them to determine the bedrock interface at a site with a detailed velocity profile. While the interface between Upper and Lower Tertiary was, until now, considered responsible for the fundamental frequency of resonance in the Rhine Graben, we found that the bedrock interface in fact lies at the Mesozoic limestone. We also investigated the second peak of the H/V ratios that is clustered in a particular area of the basin where amplification is found to be different. We successfully used the ESM amplification functions to verify the microzonation of 2006 and would strongly advise the installation of strong motion stations where such studies are performed in the future. Outside the Rhine Graben, where shallow sediments are found, we propose an amplification functional form based on ESM and the fundamental frequency of resonance. Finally, we combined all our findings and generated amplification maps of the response spectrum at any period of interest for earthquake engineering. This map is proposed for a high resolution real-time implementation in ShakeMap and will be used for seismic loss assessment.
      Graphical abstract image

      PubDate: 2016-08-10T11:13:00Z
      DOI: 10.1016/j.pce.2016.07.005
  • Seismic amplification in a fractured rock site. The case study of San
           Gregorio (L'Aquila, Italy)
    • Authors: Deborah Di Naccio; Maurizio Vassallo; Giuseppe Di Giulio; Sara Amoroso; Luciana Cantore; Salomon Hailemikael; Emanuela Falcucci; Stefano Gori; Giuliano Milana
      Abstract: Publication date: Available online 6 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Di Naccio Deborah, Vassallo Maurizio, Di Giulio Giuseppe, Amoroso Sara, Cantore Luciana, Hailemikael Salomon, Falcucci Emanuela, Gori Stefano, Giuliano Milana
      The village of San Gregorio (SG), eight kilometres away from L’Aquila (central Italy), was severely damaged by the April 6, 2009 L’Aquila earthquake (MW 6.1). A coseismic fracture zone was mapped along SW-dipping fault segments crossing SG, which is situated at the base of a carbonate relief bounded by the Aterno river alluvial plain. An interdisciplinary approach was used to investigate the seismic response of the area based on geological-structural, geophysical and seismic analyses. We integrated our data with available information from the recent microzonation studies. SG is partly built on alluvial fan deposits constituted by cemented gravel, and partly on jointed carbonate bedrock. An extensive survey of noise measurements showed strong and polarized peaks in the horizontal-to-vertical spectral ratios (H/V), both on soft and rock sites in the 2-10 Hz frequency band. Further, we checked the stability with time of H/V ratios at three sites of SG. An analysis on local earthquakes confirmed the results of noise measurements. To understand the influence of rock mass jointing condition on site effects, we performed structural surveys on carbonate bedrock. We also evaluated the propagation velocities at rock sites using seismic active and seismic dilatometer test (SDMT) surveys. Our analysis showed low values of compressional (V P ) and shear wave (V S ) velocities of the outcropping rock, where we also observed strong H/V spectral peak and high-density rock fracturing.

      PubDate: 2016-08-10T11:13:00Z
      DOI: 10.1016/j.pce.2016.07.004
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