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PHYSICS (580 journals)

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Journal Cover Physics and Chemistry of the Earth, Parts A/B/C
  [SJR: 0.624]   [H-I: 42]   [5 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1474-7065
   Published by Elsevier Homepage  [2969 journals]
  • When good practices by water committees are not relevant: sustainability
           of small water infrastructures in semi-arid mozambique
    • 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
    • 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
       
  • Polyethyleneimine-carbon nanotube polymeric nanocomposite adsorbents for
           the removal of Cr6+ from water
    • 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
       
  • Reception conditions of low frequency (LF) transmitter signals onboard
           DEMETER micro-satellite
    • 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
       
  • Forecast and optimal allocation of production, living and ecology water
           consumption in Zhangye, China
    • 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
       
  • Site amplification at the city scale in Basel (Switzerland) from
           geophysical site characterization and spectral modelling of recorded
           earthquakes
    • 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
       
  • Is small-scale irrigation an efficient pro-poor strategy in the upper
           Limpopo Basin in Mozambique?
    • Abstract: Publication date: Available online 27 June 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Raphaelle Ducrot
      In Sub-Saharan Africa, there is evidence that households with access to small-scale irrigation are significantly less poor than households that do not have access to irrigation. However, private motopumps tend to be distributed inequitably. This paper investigates the success of explicit pro-poor interventions with emphasis on small-scale irrigation in the semi-arid Limpopo Basin in Mozambique. It reveals that high irrigation costs are progressively excluding the poor, who are unable to generate a cash income from other activities they need to fund irrigation. In addition, the operation of collective schemes involving the poor is being jeopardized by the development of private irrigation schemes, which benefit from hidden subsidies appropriated by local elites. This results in unequal access to irrigation, which can cause resentment at community level. This weakens community cohesiveness, as well as communities' capacities for collective action and coordination, which are crucial for collective irrigation.


      PubDate: 2016-08-10T11:13:00Z
       
  • Recent trends of extreme precipitation indices in the Iberian Peninsula
           using observations and WRF model results
    • 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
       
  • Strategy for Management of Lake-Catchment System Integrated with Natural
           and Anthropogenic Factors in China
    • Abstract: Publication date: Available online 27 June 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Zhandong Yang, Feng Wu, Xing Gao
      Lake eutrophication that has caused severe damages to aquatic ecosystems is a hot issue in the field of water pollution control, so analyzing its process and driving mechanism is of great significance. In this study, we detected its major driving factors based on an observed dataset and assessed the impacts of these factors. Firstly, empirical econometric models were used to ascertain the Per capita GDP and the percentage of impervious surface, which are significantly related with the eutrophication level. Eutrophication is slightly affected by anthropogenic disturbance, but is negatively related to the supply coefficient. Secondly, all driving factors are divided into two categories, including the stresses caused by human activities and the comprehensive health status, which are expressed as the two coordinate axes of an indicator-matrix. Thirdly, lake classification, which is a decision-making tool for management and control of eutrophication, suggests a breakdown in communication between researchers and water managers. Finally, corresponding management strategies are recommended, and the classification system can be used to simplify management by grouping lakes that may be managed by similar strategies. The classification management may enlighten and guide the appropriate policy implementation for lake eutrophication management.


      PubDate: 2016-08-10T11:13:00Z
       
  • The impact of land use change on water balance in Zhangye city, China
    • Abstract: Publication date: Available online 27 June 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Zhongxiao Sun, Feng Wu, Chenchen Shi, Jinyan Zhan
      Land use change has a significant effect on water balance, especially in arid region, such as Northwest China. In this paper, we analyze the effect of land use change on water balance in terms of the amount of water supply and demand from economic perspective. It's the first time to extend the basic 48 sectors input-output table to include water and land accounts that involved into multiple production processes for Zhangye city. We then perform the improved ORANI-G model, a single region Computable General Equilibrium (CGE) model, to analyze the effect of land use change on water balance under three scenarios. Subsequently, scenario-based simulation results are interpreted through selected sectors from agricultural, industrial, and service sectors respectively. Finally, the effect of land use change on water balance is analyzed through the difference between business-as-usual and land use unchanged scenarios. The results show that the extent of effect on water balance is different among sectors. Specifically, from the perspective of absolute value, service sectors are the largest, followed by industrial sectors, and the agricultural sectors are the least. Conversely, in terms of percentage change of land use, the largest extent of effect occurs in agricultural sectors. Additionally, with the rapid urbanization and the development of social economy, water balance in industrial sectors and service sectors will be stricken and reconstructed to a new high level. Simulation results also show that agricultural land shrinking will mitigate water scarcity distinctly, which indicates that balance the relationship among different stakeholders is imperative to guarantee water transformation from agricultural sectors to industrial and service sectors.


      PubDate: 2016-08-10T11:13:00Z
       
  • Long time-series spatiotemporal variations of NPP and water use efficiency
           in the Lower Heihe River Basin with serious water scarcity
    • Abstract: Publication date: Available online 27 June 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Haiming Yan, Jinyan Zhan, Huicai Yang, Fan Zhang, Guofeng Wang, Wenjie He
      It is of great significance to analyze the long time-series spatiotemporal dynamics of water use efficiency (WUE) to formulating appropriate management measures in response to the growing water scarcity in arid and semi-arid regions. This study analyzed the long time-series variations of WUE in the Lower Heihe River Basin, a typical arid and semi-arid region in China. The net primary productivity (NPP) was first estimated with the C-fix model, then WUE during 2001-2010 was calculated with the NPP and evapotranspiration (ET) data, and the accumulative WUE was further calculated. The results showed that the annual NPP and WUE in the study area ranged from zero to 448.70 gC/(m2•a) and from zero to 2.20 gC kg−1 H2O, respectively, both of which showed an overall increasing trend during 2001-2010. Besides, the spatial pattern of WUE kept overall unchanged during 2001-2010, but with remarkable change in some part of the study area. In addition, the accumulative WUE of the whole study area showed a first sharply decreasing and then gradually increasing trend, but there was still some scope to improve the WUE, and it is necessary to carry out some more specific policies to further improve the water allocation and WUE within the Lower Heihe River Basin. Although with some uncertainties, these results still can provide valuable reference information for improving the water resource management and ecological conservation to guarantee provision of essential ecosystem services in arid and semi-arid regions.


      PubDate: 2016-08-10T11:13:00Z
       
  • Allocating agricultural production factors: a scenario-based modeling of
           wheat production in Shandong Province, China
    • Abstract: Publication date: Available online 27 June 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Fan Zhang, Jinyan Zhan, Qian Zhang, Haiming Yan, Zhongxiao Sun
      We aim to determine the effects of agricultural factors input per hectare on wheat production, and to optimize the allocation of wheat production factors under three scenarios and in different operating modes. Data were collected from 204 farming households using a face-to-face questionnaire. The sampled farms were selected through a stratified random sampling technique. We find fertilizer cost, irrigation cost and machinery cost all positively and significantly affect the per-unit-area wheat production, indicating the labor cost is not the major driving factor on wheat yield increment. Multi-object optimization model is used to allocate the production factors per hectare. We find under the Business as usual (BAU) scenario, the irrigation cost per-hectare wheat production after optimization in 2014 grows at a rate of 24.31% and accounts for 14.9% of total input. Under the Cooperate Environmental Sustainability (CES) scenario, the fertilizer and pesticide costs after optimization drop significantly by 42.83% and 21.41%, respectively. Under the Rapid Benefit Growth (RBG) scenario, the irrigation cost after optimization increase by 2.56% and the fertilizer cost increases by 4.69% compared with the surveyed data. Comparison of optimized data among three operating modes shows that the labor costs at household farm and cooperative farm both increase significantly. Cooperative farms are more successful in production factor use efficiency and economic performance. In conclusion, wheat production at different operating modes could be improved so as to constitute more efficient and economic use of production factors.


      PubDate: 2016-08-10T11:13:00Z
       
  • Shear-tensile crack as a tool for reliable estimates of the
           non-double-couple mechanism: West Bohemia-Vogtland earthquake 1997 swarm
    • Abstract: Publication date: Available online 29 June 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      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: 2016-08-10T11:13:00Z
       
  • S-wave velocity measurement and the effect of basin geometry on site
           response, east San Francisco Bay area, California, USA
    • Abstract: Publication date: Available online 22 July 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Koichi Hayashi, Mitchell Craig
      We measured S-wave velocity profiles at eleven sites in the east San Francisco Bay area using surface wave methods. Data acquisition included multichannel analysis of surface waves using an active source (MASW), a passive surface-wave method using a linear array of geophones (Linear-MAM), and a two-station spatial autocorrelation method (2ST-SPAC) using long-period accelerometers. Maximum distance between stations ranged from several hundred meters to several kilometers, depending on the site. Minimum frequency ranged from 0.2 to 2 Hz, depending on the site, corresponding to maximum wavelengths of 10 to 1 km. Phase velocities obtained from three methods were combined into a single dispersion curve for each site. A nonlinear inversion was used to estimate S-wave velocity profiles to a depth of 200–2000 m, depending on the site. Resultant S-wave velocity profiles show significant differences among the sites. On the west side of the Hayward fault and the east side of the Calaveras fault, there is a low velocity layer at the surface, with S-wave velocity less than 700 m/s, to a depth of approximately 100 m. A thick intermediate velocity layer with S-wave velocity ranging from 700 to 1500 m/s lies beneath the low velocity layer. Bedrock with S-wave velocity greater than 1500 m/s was measured at depths greater than approximately 1700 m. Between the Hayward Fault and the Calaveras Fault, thicknesses of the low velocity layer and the intermediate velocity layer are less than 50 m and 200 m respectively, and depth to bedrock is less than 250 m. To evaluate the effect of a lateral change in bedrock depth on surface ground motion due to an earthquake, a representative S-wave velocity cross section perpendicular to the Hayward fault was constructed and theoretical amplification was calculated using a viscoelastic finite-difference method. Calculation results show that the low frequency (0.5–5 Hz) component of ground motion is locally amplified on the west side of the Hayward fault because of the effect of two-dimensional structure.


      PubDate: 2016-08-10T11:13:00Z
       
  • The Sustainability of Drinking Water Supply in Rural China: Does the
           Provision of Drinking Water Investment Mismatch the Demand of Residents?
    • Abstract: Publication date: Available online 27 July 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Ying Liu, Tang Yao, Yu Liu
      It is doubted that the top down nature of investment planning may lead to mismatches between drinking water investment and the demands of local residents in rural China. Statistical and econometric analysis based on data of 2020 rural households from five Chinese provinces from 1998 to 2011 are used to illustrate the linkage between demand for drinking water investment and construction of drinking water projects. Household’s demand significantly affects drinking water projects implemented by upper level governments and implemented jointly, but is not significant in explaining the projects implemented by village. There is evidence to suggest that the demands of local leaders override those of households in the implementation of drinking water projects provided by village in the early stage of 2005-2008. The situation improves in the latter stage of 2008-2011when the village level participatory bodies begin to provide opportunities for households to voice their preferences on public goods investment. The results of this study imply that it is important to explore appropriate regulations and policies that enabling local cadres to better meet local demands of their communities to ensure the sustainability of rural drinking water supply.


      PubDate: 2016-08-10T11:13:00Z
       
  • Seismic amplification in a fractured rock site. The case study of San
           Gregorio (L'Aquila, Italy)
    • 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
       
  • A diagnosis of sub-surface water table dynamics in low hydraulic
           conductivity soils in the sugar cane fields of Pongola, South Africa
    • Abstract: Publication date: April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 92
      Author(s): Mphatso Malota, Aidan Senzanje
      Water and land are the two natural resources restraining crop production in South Africa. With the increasing demand for food, emphasis has shifted from the sole reliance on rain fed crop production, to irrigation. The deterioration in irrigation water quality from surface water sources is, however, posing a big challenge to the sustainability of irrigated crop production. This is because more water is required for leaching, resulting in shallow water tables in agricultural lands. The installation of well designed subsurface drainage systems alone is not enough; the provision of timely maintenance is also necessary. In this study, the extent and severity of problems as a consequence of shallow water tables and their possible causes were investigated at three sugarcane fields in Pongola, South Africa, having low hydraulic conductivity soils. Also investigated were soil salinity levels and the temporal variation in the salinity of the irrigation water. A water table map of a 32 ha sugarcane field was generated, using observed water table depth (WTD) data from 36 piezometers monitored from September 2011 to February 2012. Out of the total 32 ha under cultivation, 12% was found to be affected by shallow WTDs of less than the 1.0 m design WTD. The inability of natural drainage to cope with subsurface drainage needs and the poor maintenance of subsurface drainage systems contributed to the shallow water tables in the area. Furthermore, the currently adopted drainage design criteria also proved unsatisfactory with mean observed water table depth and drainage discharge (DD) of 20% and 50%, respectively, less than their respective design levels. The salinity of the irrigation water was, on average, 32% higher than threshold tolerance level of sugarcane. The root zone soil salinity levels at the three study sites were greater than the 1.7 dS m−1 threshold for sugar cane. The subsurface drainage design criteria adopted at the site needs to be revisited by ensuring that the slope of the land is taken into consideration in the drainage design in addition to adhering to a recommended maintenance schedule.


      PubDate: 2016-06-15T15:51:38Z
       
  • Determination of the health of Lunyangwa wetland using Wetland
           Classification and Risk Assessment Index
    • Abstract: Publication date: April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 92
      Author(s): Elijah M.M. Wanda, Bhekie B. Mamba, Titus A.M. Msagati, Golden Msilimba
      Wetlands are major sources of various ecological goods and services including storage and distribution of water in space and time which help in ensuring the availability of surface and groundwater throughout the year. However, there still remains a poor understanding of the range of values of water quality parameters that occur in wetlands either in its impacted state or under natural conditions. It was thus imperative to determine the health of Lunyangwa wetland in Mzuzu City in Malawi in order to classify and determine its state. This study used the Escom's Wetland Classification and Risk Assessment Index Field Guide to determine the overall characteristics of Lunyangwa wetland and to calculate its combined Wetland Index Score. Data on site information, field measurements (i.e. EC, pH, temperature and DO) and physical characteristics of Lunyangwa wetland were collected from March, 2013 to February, 2014. Results indicate that Lunyangwa wetland is a largely open water zone which is dominated by free-floating plants on the water surface, beneath surface and emergent in substrate. Furthermore, the wetland can be classified as of a C ecological category (score = 60–80%), which has been moderately modified with moderate risks of the losses and changes occurring in the natural habitat and biota in the wetland. It was observed that the moderate modification and risk were largely because of industrial, agricultural, urban/social catchment stressors on the wetland. This study recommends an integrated and sustainable management approach coupled with continuous monitoring and evaluation of the health of the wetland for all stakeholders in Mzuzu City. This would help to maintain the health of Lunyangwa wetland which is currently at risk of being further modified due to the identified catchment stressors.


      PubDate: 2016-06-15T15:51:38Z
       
  • Geochemical modelling and speciation studies of metal pollutants present
           in selected water systems in South Africa
    • Abstract: Publication date: April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 92
      Author(s): M.M. Magu, P.P. Govender, J.C. Ngila
      Metal pollutants in water poses great threats to living beings and hence requires to be monitored regularly to avoid loss of lives. Various analytical methods are available to monitor these pollutants in water and can be improved with time. Modelling of metal pollutants in any water system helps chemists, engineers and environmentalists to greatly understand the various chemical processes in such systems. Water samples were collected from waste water treatment plant and river from highlands close to its source all the way to the ocean as it passing through areas with high anthropogenic activities. Pre-concentration of pollutants in the samples was done through acid digestion and metal pollutants were analysed using inductively coupled plasma-optical emission spectra (ICP-OES) to determine the concentration levels. Metal concentrations ranged between 0.1356–0.4658mg/L for Al; 0.0031–0.0050mg/L for Co, 0.0019–0.0956mg/L for Cr; 0.0028–0.3484mg/L for Cu; 0.0489–0.3474mg/L for Fe; 0.0033–0.0285mg/L for Mn; 0.0056–0.0222mg/L for Ni; 0.0265–0.4753mg/L for Pb and 0.0052–0.5594mg/L for Zn. Modelling work was performed using PHREEQC couple with Geochemist’s workbench (GWB) to determine speciation dynamics and bioavailability of these pollutants. Modelling thus adds value to analytical methods and hence a better complementary tool to laboratory-based experimental studies.


      PubDate: 2016-06-15T15:51:38Z
       
  • Spatial scale impact on daily surface water and sediment fluxes in Thukela
           river, South Africa
    • Abstract: Publication date: April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 92
      Author(s): Macdex Mutema, Graham Jewitt, Pauline Chivenge, Samuel Kusangaya, Vincent Chaplot
      The on- and off-site effects of soil erosion in many environments are well known, but there is still limited understanding of the soil loss fluxes in downstream direction due, among other factors, to scarce and poor quality. A four year study to (i) evaluate water and sediment fluxes at different spatio-temporal scales and (ii) interpret the results in terms of processes involved and the controlling factors, was conducted in Thukela basin, South Africa. Five hierarchically nested catchments; namely microcatchment (0.23 km2), subcatchment (1.20 km2), catchment (9.75 km2), sub-basin (253 km2) and basin (29,038 km2), were used in addition to fifteen (1 m2) microplots and ten (10 m2) plots on five locations within the microcatchment. The results showed 19% decrease of unit-area runoff (q) from 3.1 L m−2 day−1 at microplot to 2.5 L m−2 day−1 at plot scale followed by steeper (56%) decrease at microcatchment scale. The q decreased in downstream direction to very low level (q ≤ 0.26 L m−2 day−1). The changes in q were accompanied by initial 1% increase of soil loss (SL) from 18.8 g m−2 day−1 at microplot to 19.1 g m−2 day−1 at plot scale. The SL also decreased sharply (by 39 fold) to 0.50 g m−2 day−1 at microcatchment scale, followed by further decrease in downstream direction. The decrease of q with spatial scale was attributed to infiltration losses, while initial increase of SL signified greater competence of sheet than splash erosion. The decrease of SL beyond the plot scale was attributed to redistribution of the soil on the hillslope and deposition on the stream channel upstream of the microcatchment outlet. Therefore, erosion control strategies focussing on the recovery of vegetation on the slope and stabilisation of gullies are recommended.


      PubDate: 2016-06-15T15:51:38Z
       
  • Rural food insecurity and poverty mappings and their linkage with water
           resources in the Limpopo River Basin
    • Abstract: Publication date: April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 92
      Author(s): M.S. Magombeyi, A.E. Taigbenu, J. Barron
      The mappings of poverty and food insecurity were carried out for the rural districts of the four riparian countries (Botswana, Mozambique, South Africa and Zimbabwe) of the Limpopo river basin using the results of national surveys that were conducted between 2003 and 2013. The analysis shows lower range of food insecure persons (0–40%) than poverty stricken persons (0–95%) that is attributable to enhanced government and non-government food safety networks in the basin countries, the dynamic and transitory nature of food insecurity which depends on the timings of the surveys in relation to harvests, markets and food prices, and the limited dimension of food insecurity in relation to poverty which tends to be a more structural and pervasive socio-economic condition. The usefulness of this study in influencing policies and strategies targeted at alleviating poverty and improving rural livelihoods lies with using food insecurity mappings to address short-term socio-economic conditions and poverty mappings to address more structural and long-term deprivations. Using the poverty line of $1.25/day per person (2008–2013) in the basin, Zimbabwe had the highest percentage of 68.7% of its rural population classified as poor, followed by Mozambique with 68.2%, South Africa with 56.1% and Botswana with 20%. While average poverty reduction of 6.4% was observed between 2003 and 2009 in Botswana, its population growth of 20.1% indicated no real poverty reduction. Similar observations are made about Mozambique and Zimbabwe where population growth outstripped poverty reductions. In contrast, both average poverty levels and population increased by 4.3% and 11%, respectively, in South Africa from 2007 to 2010. While areas of high food insecurity and poverty consistently coincide with low water availability, it does not indicate a simple cause–effect relationship between water, poverty and food insecurity. With limited water resources, rural folks in the basin require stronger institutions, increased investments and support to enable them generate sufficient income from their rain-fed farming livelihood to break out of the poverty cycle.


      PubDate: 2016-06-15T15:51:38Z
       
  • Superhydrophobic and superoleophillic surface of porous beaded electrospun
           polystrene and polysytrene-zeolite fiber for crude oil-water separation
    • Abstract: Publication date: April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 92
      Author(s): S. Oluwagbemiga Alayande, E. Olugbenga Dare, Titus A.M. Msagati, A. Kehinde Akinlabi, P.O. Aiyedun
      This research presents a cheap route procedure for the preparation of a potential adsorbent with superhydrophobic/superoleophillic properties for selective removal of crude oil from water. In this study, expanded polystyrene (EPS) was electrospun to produce beaded fibers in which zeolite was introduced to the polymer matrix in order to impart rough surface to non-beaded fiber. Films of the EPS and EPS/Zeolite solutions were also made for comparative study. The electrospun fibers EPS, EPS/Zeolite and resultant films were characterized using SEM, BET, FTIR and optical contact angle. The fibers exhibited superhydrophobic and superoleophillic wetting properties with water (>1500) and crude oil (00). The selective removal of crude oil presents new opportunity for the re-use of EPS as adsorbent in petroleum/petrochemical industry.


      PubDate: 2016-06-15T15:51:38Z
       
  • Impact of urbanization on the ecology of Mukuvisi River, Harare, Zimbabwe
    • Abstract: Publication date: April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 92
      Author(s): N.A.G. Moyo, M.M. Rapatsa
      The main objective in this study was to compare the physico-chemical characteristics and biota of a river (Mukuvisi) passing through an urban area to that of a non-urbanised river (Gwebi). Five sites in the Mukuvisi River and five sites in the Gwebi River were sampled for water physico-chemical parameters (pH, conductivity, DO, BOD, TDS, ammonia, Cl, SO4 2−, PO4 2−, NO3 3−, F−, Pb, Cu, Fe, Mn, Zn and Cr) once every month between August, 2012–August, 2013. Cluster analysis based on the physico-chemical parameters grouped the sites into two groups. Mukuvisi River sites formed their own grouping except for one site which was grouped with Gwebi River sites. Principal Component Analysis (PCA) was used to extract the physico-chemical parameters that account for most variations in water quality in the Mukuvisi and Gwebi Rivers. PCA identified sulphate, chloride, fluoride, iron, manganese and zinc as the major factors contributing to the variability of Mukuvisi River water quality. In the Gwebi river, sulphate, nitrate, fluoride and copper accounted for most of the variation in water quality. Canonical Correspondence Analysis (CCA) was used to explore the relationship between physico-chemical parameters and macroinvertebrate communities. CCA plots in both Mukuvisi and Gwebi Rivers showed significant relationships between macroinvertebrate communities and water quality variables. Phosphate, ammonia and nitrates were correlated with Chironomidae and Simulidae. Gwebi River had higher (P < 0.05, ANOVA) macroinvertebrates and fish diversity than Mukuvisi River. Clarias gariepinus from the Mukuvisi River had high liver histological lesions and low AChE activity and this led to lower growth rates in this river.


      PubDate: 2016-06-15T15:51:38Z
       
  • Water: The conveyor belt for sustainable livelihoods and economic
           development
    • Abstract: Publication date: April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 92
      Author(s): Benjamin Mapani, Maideyi Meck, Hodson Makurira, Lapologang Magole, Damas Mashauri, Dominic mazvimavi, Marloes Mul



      PubDate: 2016-06-15T15:51:38Z
       
  • Superoleophillic electrospun polystrene/exofoliated graphite fibre for
           selective removal of crude oil from water
    • Abstract: Publication date: April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 92
      Author(s): S. Oluwagbemiga Alayande, Enock O. Dare, F.O. Grace Olorundare, D. Nkosi, Titus A.M. Msagati, B.B. Mamba
      During oil spills, the aquatic environment is greatly endangered because oil floats on water making the penetration of sunlight difficult therefore primary productivity is compromised, birds and aquatic organisms are totally eliminated within a short period. It is therefore essential to remove the oil from the water bodies after the spillage. This work reports on the fabrication of oil loving electrospun polystyrene-exofoliated graphite fibre with hydrophobic and oleophillic surface properties. The fibre was applied for the selective adsorption of crude oil from simulated crude oil spillage on water. The maximum oil adsorption capacity of the EPS/EG was 1.15 kg/g in 20 min while the lowest oil adsorption capacity was 0.81 kg/g in 10 min. Cheap oil adsorbent was developed with superoleophillic and superhydrophobic properties.


      PubDate: 2016-06-15T15:51:38Z
       
  • A ten year Moment Tensor database for Western Greece
    • Abstract: Publication date: Available online 20 May 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      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: 2016-06-15T15:51:38Z
       
  • Identification of blasting sources in the Dobrogea seismogenic region,
           Romania using seismo-acoustic signals
    • Abstract: Publication date: Available online 20 May 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      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: 2016-06-15T15:51:38Z
       
  • Ungauged runoff simulation in Upper Manyame Catchment, Zimbabwe:
           Applications of the HEC-HMS model
    • Abstract: Publication date: Available online 24 May 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Webster Gumindoga, Donald T. Rwasoka, Innocent Nhapi, Timothy Dube
      The Hydrologic Engineering Centre Hydrologic Modelling System model was applied to simulate runoff in the ten gauged and ungauged Upper Manyame micro-catchments in Zimbabwe. Remote sensing and Geographic Information System techniques were used to determine the geometric and hydrologic parameters required for estimating model parameters. The Snyder Unit Hydrograph method was used for ungauged catchment simulations based on parameter transfer from gauged micro-catchments. The Marimba and Mukuvisi micro-catchments were considered as the gauged micro-catchments based on data completeness for the simulation period (2004-2010). Before extrapolating the calibrated model setup to eight ungauged micro-catchments, the feasibility of model parameter transferability was tested, using the proxy catchment approach and evaluated using the Nash Sutcliffe (NSE) and Relative Volume Error (RVE) criterion. Results showed that the model successfully predicted gauged catchment runoff and peakflows for the calibration (Marimba NSE= 68 %, RVE= -5.8 %; Mukuvisi NSE 64 %=, RVE= 8.9 %) and validation (Marimba NSE= 61 %, RVE= 8.1 %; Mukuvisi NSE 57 %=, RVE= -9.9 %) periods. The study demonstrates the suitability of HEC-HMS for continuous runoff simulation in a complex watershed with numerous micro-catchments and channel reaches. The ungauged micro-catchments contribute to 88 % of Upper Manyame Catchment’s runoff. Therefore, this work will have a significant contribution for the future development of water resources programs in in this catchment in particular and in other data-scarce catchments.


      PubDate: 2016-06-15T15:51:38Z
       
  • Regionalization of Europe based on a K-Means Cluster Analysis of the
           climate change of temperatures and precipitation
    • 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
       
  • Robust inferences on climate change patterns of precipitation extremes in
           the Iberian Peninsula
    • Abstract: Publication date: Available online 1 June 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Paulo de Melo-Gonçalves, Alfredo Rocha, João Santos
      This work presents a methodology to make statistical significant and robust inferences on climate change from an ensemble of model simulations. This methodology is used to assess climate change projections of the Iberian daily-total precipitation for a near-future (2021 – 2050) and a distant-future (2069 – 2098) climates, relatively to a reference past climate (1961 – 1990). Climate changes of precipitation spatial patterns are estimated for annual and seasonal values of: (i) total amount of precipitation (PRCTOT), (ii) maximum number of consecutive dry days (CDD), (iii) maximum of total amount of 5-consecutive wet days (Rx5day), and (iv) percentage of total precipitation occurred in days with precipitation above the 95 t h percentile of the reference climate (R95T). Daily-total data were obtained from the multi-model ensemble of fifteen Regional Climate Model simulations provided by the European project ENSEMBLES. These regional models were driven by boundary conditions imposed by Global Climate Models that ran under the 20C3M conditions from 1961 to 2000, and under the A1B scenario, from 2001 to 2100, defined by the Special Report on Emission Scenarios of the Intergovernmental Panel on Climate Change. Non-parametric statistical methods are used for significant climate change detection: linear trends for the entire period (1961 – 2098) estimated by the Theil-Sen method with a statistical significance given by the Mann-Kendall test, and climate-median differences between the two future climates and the past climate with a statistical significance given by the Mann-Whitney test. Significant inferences of climate change spatial patterns are made after these non-parametric statistics of the multi-model ensemble median, while the associated uncertainties are quantified by the spread of these statistics across the multi-model ensemble. Significant and robust climate change inferences of the spatial patterns are then obtained by building the climate change patterns using only the grid points where a significant climate change is found with a predefined low uncertainty. Results highlight the importance of taking into account the spread across an ensemble of climate simulations when making inferences on climate change from the ensemble-mean or ensemble-median. This is specially true for climate projections of extreme indices such CDD and R95T. For PRCTOT, a decrease in annual precipitation over the entire peninsula is projected, specially in the north and northwest where it can decrease down to 400 mm by the middle of the 21st century. This decrease is expected to occur throughout the year except in winter. Annual CDD is projected to increase till the middle of 21st century overall the peninsula, reaching more than three weeks in the southwest. This increase is projected to occur in summer and spring. For Rx5day, a decrease is projected to occur during spring and autumn in the major part of the peninsula, and during summer in northern Iberia. Finally, R95T is projected to decrease around 20% in northern Iberia in summer, and around 15% in the south-southwest in autumn.


      PubDate: 2016-06-15T15:51:38Z
       
  • Comparative assessment of water treatment using polymeric and inorganic
           coagulants
    • Abstract: Publication date: June 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 93
      Author(s): Innocent K.M. Manda, Russel C.G. Chidya, John D.K. Saka, Timothy T. Biswick
      Portable water plays a vital role in improving human life, particularly in controlling the spread of diseases. However, problems associated with lack of potable water are still common especially in developing countries including Malawi. Until now little information exists on the effectiveness of available commercial coagulants used by national water boards in Malawi. Therefore, this study was undertaken in Southern Region Water Board (SRWB) to investigate the efficiency of polymeric coagulants (sufdfloc 3850 and algaefloc 19s) in turbidity reduction comparative with inorganic coagulant (aluminium sulphate) at Zomba, Liwonde, Mangochi, Chikwawa and Mulanje Treatment plants. The jar test method was used to determine the effectiveness of the water coagulants. The results revealed that sudfloc 3850 was most effective in reducing turbidity at Mangochi (99.4 ± 0.06%) and Liwonde (97.2 ± 0.04%) using 0.4 mg L−1 flocculant dose. The Zomba, Mulanje and Chikwawa plants gave 19.56 ± 0.03%, 29.23 ± 0.02% and 9.43 ± 0.02% total reductions respectively. Algaefloc 19s afforded the highest turbidity reduction at Liwonde and Mangochi plants (98.66 ± 0.06 and 97.48 ± 0.05% at a dose of 0.4 and 0.6 mg L−1 respectively), while Chikwawa provided the lowest (9.52 ± 0.01%). At the Zomba and Mulanje plants 20.5 ± 0.03% and 28.4 ± 0.04% reductions were obtained respectively. The inorganic flocculant, alum provided a 99.0 ± 0.05% and 98.6 ± 0.04% reduction at a dose of 4.0 mg L−1 and 6.0 mg L−1 at Zomba and Liwonde plants respectively. The lowest reductions in turbidity were achieved at Chikwawa (7.50 ± 0.01%), Mangochi (12.97 ± 0.02%) and Mulanje (25.00 ± 0.02). The best and optimum pH ranges for polymeric and inorganic coagulants were 7.20–7.80 and 7.35 to 7.57 respectively. The results further revealed that sudfloc 3850 and algaefloc 19s achieved faster formation of heavy flocs than alum. At 0.4 mg L−1 flocculant dosage sudfloc 3850 and algaefloc 19s required ten times lower dosages than alum. Therefore, the polymeric coagulants could be used instead of alum, the choice dependant on the type of water.


      PubDate: 2016-06-15T15:51:38Z
       
  • Hydraulic design to optimize the treatment capacity of Multi-Stage
           Filtration units
    • Abstract: Publication date: April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 92
      Author(s): C.N. Mushila, G.M. Ochieng, F.A.O. Otieno, S.M. Shitote, C.W. Sitters
      Multi-Stage Filtration (MSF) can provide a robust treatment alternative for surface water sources of variable water quality in rural communities at low operation and maintenance costs. MSF is a combination of Slow Sand Filters (SSFs) and Pre-treatment systems. The general objective of this research was to optimize the treatment capacity of MSF. A pilot plant study was undertaken to meet this objective. The pilot plant was monitored for a continuous 98 days from commissioning till the end of the project. Three main stages of MSF namely: The Dynamic Gravel Filter (DGF), Horizontal-flow Roughing Filter (HRF) and SSF were identified, designed and built. The response of the respective MSF units in removal of selected parameters guiding drinking water quality such as microbiological (Faecal and Total coliform), Suspended Solids, Turbidity, PH, Temperature, Iron and Manganese was investigated. The benchmark was the Kenya Bureau (KEBS) and World Health Organization (WHO) Standards for drinking water quality. With respect to microbiological raw water quality improvement, MSF units achieved on average 98% Faecal and 96% Total coliform removal. Results obtained indicate that implementation of MSF in rural communities has the potential to increase access to portable water to the rural populace with a probable consequent decrease in waterborne diseases. With a reduced down time due to illness, more time would be spent in undertaking other economic activities.


      PubDate: 2016-06-15T15:51:38Z
       
  • Gender and power contestations over water use in irrigation schemes:
           Lessons from the lake Chilwa basin
    • Abstract: Publication date: April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 92
      Author(s): Bryson Nkhoma, Gift Kayira
      Over the past two decades, Malawi has been adversely hit by climatic variability and changes, and irrigation schemes which rely mostly on water from rivers have been negatively affected. In the face of dwindling quantities of water, distribution and sharing of water for irrigation has been a source of contestations and conflicts. Women who constitute a significant section of irrigation farmers in schemes have been major culprits. The study seeks to analyze gender contestations and conflicts over the use of water in the schemes developed in the Lake Chilwa basin, in southern Malawi. Using oral and written sources as well as drawing evidence from participatory and field observations conducted at Likangala and Domasi irrigation schemes, the largest schemes in the basin, the study observes that women are not passive victims of male domination over the use of dwindling waters for irrigation farming. They have often used existing political and traditional structures developed in the management of water in the schemes to competitively gain monopoly over water. They have sometimes expressed their agency by engaging in irrigation activities that fall beyond the control of formal rules and regulations of irrigation agriculture. Other than being losers, women are winning the battle for water and land resources in the basin.


      PubDate: 2016-06-15T15:51:38Z
       
  • Managing ground and surface water resources using innovative methods in
           rural and urban areas of Sub-Saharan Africa
    • Abstract: Publication date: June 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 93
      Author(s): Benjamin Mapani, Lapologang Magole, Hodson Makurira, Dominic Mazvimavi, Maideyi Meck, Maloes Mul



      PubDate: 2016-06-15T15:51:38Z
       
  • Assessment of impact of climate change and adaptation strategies on maize
           production in Uganda
    • Abstract: Publication date: June 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 93
      Author(s): Duncan A. Kikoyo, Joel Nobert
      Globally, various climatic studies have estimated a reduction of crop yields due to changes in surface temperature and precipitation especially for the developing countries which is heavily dependent on agriculture and lacks resources to counter the negative effects of climate change. Uganda's economy and the wellbeing of its populace depend on rain-fed agriculture which is susceptible to climate change. This study quantified the impacts of climate change and variability in Uganda and how coping strategies can enhance crop production against climate change and/or variability. The study used statistical methods to establish various climate change and variability indicators across the country, and uses the FAO AquaCrop model to simulate yields under possible future climate scenarios with and without adaptation strategies. Maize, the most widely grown crop was used for the study. Meteorological, soil and crop data were collected for various districts representing the maize growing ecological zones in the country. Based on this study, it was found that temperatures have increased by up to 1 °C across much of Uganda since the 1970s, with rates of warming around 0.3 °C per decade across the country. High altitude, low rainfall regions experience the highest level of warming, with over 0.5 °C/decade recorded in Kasese. Rainfall is variable and does not follow a specific significant increasing or decreasing trend. For both future climate scenarios, Maize yields will reduce in excess of 4.7% for the fast warming-low rainfall climates but increase on average by 3.5% for slow warming-high rainfall regions, by 2050. Improved soil fertility can improve yields by over 50% while mulching and use of surface water management practices improve yields by single digit percentages. The use of fertilizer application needs to go hand in hand with other water management strategies since more yields as a result of the improved soil fertility leads to increased water stress, especially for the dry climates.


      PubDate: 2016-06-15T15:51:38Z
       
  • Implementing Integrated Catchment Management in the upper Limpopo River
           basin: A situational assessment
    • Abstract: Publication date: June 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 93
      Author(s): J. Mwenge Kahinda, R. Meissner, F.A. Engelbrecht
      A three-phase study was initiated as a way to promote Integrated Catchment Management approaches in the Limpopo River basin. This paper presents the situational assessment, which should enable De Beers to understand how their Venetia Mine operations are located within a broader and highly dynamic socio-economic and ecohydrological landscape as it pertains to water risks. The second phase, Risk assessment, aims to develop conservation interventions in the identified areas; the third phase will develop mechanisms for implementing water stewardship schemes to mitigate the shared water risks. Analysis of the social-ecological system (hydrological, climatic, ecological, socio-economic and governance systems) of the Limpopo River basin indicates that the institutional arrangement of the Limpopo River basin is neither simple nor effective. The basin is rapidly approaching closure in the sense that almost all of the available supplies of water have already been allocated to existing water users. If the proposed ecological flow requirements were to be met for all of the tributaries, the basin would be ‘closed’. On-going and projected land use changes and water resources developments in the upper reaches of the basin, coupled with projected rainfall reductions and temperature increases, and allocation of the flows for the ecological reserve, are likely to further reduce downstream river flows. The coupled increase in temperature and decrease in rainfall is of great concern for everyone in the basin, especially the poorer communities, who rely on rain-fed agriculture for their livelihoods. Increased temperatures also lead to increased evaporation from reservoirs and therefore result in a decrease in water availability. This will lead to increased abstraction of groundwater, especially from alluvial aquifers, and consequently an increase in river transmission losses and a decrease in river flows.


      PubDate: 2016-06-15T15:51:38Z
       
  • Determination of the water quality index ratings of water in the
           Mpumalanga and North West provinces, South Africa
    • Abstract: Publication date: April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 92
      Author(s): Elijah M.M. Wanda, Bhekie B. Mamba, Titus A.M. Msagati
      This study reports on the water quality index (WQI) of wastewater and drinking water in the Mpumalanga and North West provinces of South Africa. The WQI is one of the most effective tools available to water sustainability researchers, because it provides an easily intelligible ranking of water quality on a rating scale from 0 to 100, based on the ascription of different weightings to several different parameters. In this study the WQI index ratings of wastewater and drinking water samples were computed according to the levels of pH, electrical conductivity (EC), biochemical oxygen demand (BOD), E. coli, temperature, turbidity and nutrients (nitrogen and phosphates) found in water samples collected from the two provinces between June and December, 2014. This study isolated three groups of WQ-rated waters, namely: fair (with a WQI range = 32.87–38.54%), medium (with a WQI range = 56.54–69.77%) and good (with a WQI range = 71.69–81.63%). More specifically, 23%, 23% and 54% of the sampled sites registered waters with fair, medium and good WQ ratings respectively. None of the sites sampled during the entire period of the project registered excellent or very good water quality ratings, which would ordinarily indicate that no treatment is required to make it fit for human consumption. Nevertheless, the results obtained by the Eerstehoek and Schoemansville water treatment plants in Mpumalanga and North West provinces, respectively, suggest that substantial improvement in the quality of water samples is possible, since the WQI values for all of the treated samples were higher than those for raw water. Presence of high levels of BOD, low levels of dissolved oxygen (DO), E. coli, nitrates and phosphates especially in raw water samples greatly affected their overall WQ ratings. It is recommended that a point-of-use system should be introduced to treat water intended for domestic purposes in the clean-water-deprived areas.


      PubDate: 2016-06-15T15:51:38Z
       
  • A new approach for computing a flood vulnerability index using cluster
           analysis
    • Abstract: Publication date: Available online 22 April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Paulo Fernandez, Sandra Mourato, Madalena Moreira, Luísa Pereira
      A Flood Vulnerability Index (FloodVI) was developed using Principal Component Analysis (PCA) and a new aggregation method based on Cluster Analysis (CA). PCA simplifies a large number of variables into a few uncorrelated factors representing the social, economic, physical and environmental dimensions of vulnerability. CA groups areas that have the same characteristics in terms of vulnerability into vulnerability classes. The grouping of the areas determines their classification contrary to other aggregation methods in which the areas’ classification determines their grouping. While other aggregation methods distribute the areas into classes, in an artificial manner, by imposing a certain probability for an area to belong to a certain class, as determined by the assumption that the aggregation measure used is normally distributed, CA does not constrain the distribution of the areas by the classes. FloodVI was designed at the neighbourhood level and was applied to the Portuguese municipality of Vila Nova de Gaia where several flood events have taken place in the recent past. The FloodVI sensitivity was assessed using three different aggregation methods: the sum of component scores, the first component score and the weighted sum of component scores. The results highlight the sensitivity of the FloodVI to different aggregation methods. Both sum of component scores and weighted sum of component scores have shown similar results. The first component score aggregation method classifies almost all areas as having medium vulnerability and finally the results obtained using the CA show a distinct differentiation of the vulnerability where hot spots can be clearly identified. The information provided by records of previous flood events corroborate the results obtained with CA, because the inundated areas with greater damages are those that are identified as high and very high vulnerability areas by CA. This supports the fact that CA provides a reliable FloodVI.


      PubDate: 2016-04-24T13:42:01Z
       
  • Assessing the feasibility of integrating remote sensing and in-situ
           
    • Abstract: Publication date: Available online 22 April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): S. Dlamini, I. Nhapi, W. Gumindoga, T. Nhiwatiwa, T. Dube
      This work investigates the likelihood of integrating the cheap and readily-available broadband multispectral MODIS data and in-situ measurements in quantifying and monitoring water quality status of an inland lake within Upper Manyame Catchment in Zimbabwe. Specifically we used MODIS images to quantify inland lake chlorophyll_a concentrations, as a proxy for predicting lake pollution levels. The findings of this study show a high chlorophyll_a concentration of 0.101±0.128 μg/L within the Lake. The results further demonstrated that the chlorophyll_a concentration levels did not significantly vary (p = 0.788) between sites, except among depths (p=0.05). Further, prediction results based on the relationship between observed and predicted chlorophyll_a produced a high R2 value of 0.89 and a root mean square error (RMSE) value of 0.003 μg/L. Moreover, the derived landuse maps of Upper Manyame Catchment indicated a significant variation in the percentage settlement in 1985, 1994 and 2010 change from 1985 to 2010. For instance, 8% increase in settlement in the period between 1994 and 2010 and over 12% increase from 1985 to 2010 and a decline in percent forest coverage (i.e. 9.8% in 1985 to 2.0% in the year 2010) in the catchment was observed. Overall, the findings of this study highlights the importance of free and readily-available satellite datasets (such as the multispectral MODIS and Landsat) in quantifying and monitoring water quality across inland lakes especially in data-scarce areas like Sub-Saharan Africa.


      PubDate: 2016-04-24T13:42:01Z
       
  • The Typical Seismic Behavior in the Vicinity of a Large Earthquake
    • Abstract: Publication date: Available online 22 April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      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 1,000) 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: 2016-04-24T13:42:01Z
       
  • Anomalous behavior of ionospheric parameters above the Kamchatka peninsula
           before and during seismic activity
    • Abstract: Publication date: Available online 24 April 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Vadim V. Bogdanov, Aleksandr V. Kaisin, Aleksey V. Pavlov, Anastasia L. Polyukhova, Claudia-Veronika Meister
      In the present work, searching for new methods of earthquake prediction, variations of ionospheric plasma parameters and ionospheric turbulence before and during seismic activity are studied applying complex radiophysical methods and a theoretical probabilistic approach. The analysis of radiophysical observations of some seismic events of February-March (28.02.–02.03.) 2013 shows, that K-layer formation (appearance of a corpuscular layer due to precipitation of particles from the radiation belts), E s - and F-spread effects as well as an increase of the critical f o F2-frequency occurred about one day before earthquakes with a magnitude M≥6.5. F2-spread was even observed at low geomagnetic activity. One seismic shock was preceded by an abnormal increase in the value of the critical frequency f o F2, and about two hours after the shock, f o F2 was again well below the median value although a geomagnetic storm happened. Therefore, it may be concluded that, in future, variations of ionospheric plasma parameters and turbulence may be used as additional tool to determine the magnitude of preparing strong earthquakes. The propabilistic method which is applied in the present work is already described in (Bogdanov et al., J. Volcanology and Seismology, 4(6), 412–422, 2010). It allowed to detect a growth of seismic activity in the Kamchatka region in 2013.


      PubDate: 2016-04-24T13:42:01Z
       
  • Critical Pollution levels in Umguza River, Zimbabwe
    • Abstract: Publication date: Available online 21 March 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A. Chinyama, R. Ncube, W. Ela
      In most countries worldwide regulatory bodies set effluent discharge limits into rivers and other natural water bodies. These limits specify the maximum permissible concentration of defined pollutants that may be discharged into the water body. This limit is conceptually based on the self-purification (assimilative) capacity of the receiving water. However, this self-purification constant is itself a function of the water’s pollutant loading. Umguza River situated south west of Zimbabwe, is fed by tributaries that drain an urban catchment and as such is prone to pollution due to human activities in the catchment. This study investigated the levels of pollution in Umguza River that would affect its self-purification capacity. This was achieved by characterising the spatial distribution of a selected range of water quality parameters as well as determining the self-purification capacity of a stretch of the river. Critical pollutant concentrations were determined for some of the parameters that showed high values along the stretch. The selected parameters of interest were dissolved oxygen, suspended solids, phosphates, nitrates, COD, turbidity, ammonia, pH, alkalinity and temperature. The study was carried out from January 2014 to April 2014. The self-purification capacity was determined using a formula that compares the mass flux of a pollutant upstream and downstream of the selected stretch of the river. Statistical analysis was used to establish relationships between the pollutants and the self-purification capacity of the river. The study found that the levels of ammonia and phosphates were very high compared to the regulated limits (2mg/l vs 0.5mg/l; and 8mg/l vs 0.5mg/l respectively). It was also found that the self-purification capacity varied significantly across pollutants. It was therefore concluded that a critical pollutant concentration exists above which the river completely loses its natural ability to assimilate and decrease its pollutant load over time. It was also concluded that the self-purification capacity depends on the pollutant of concern in the river. It is recommended that the self-purification capacity of a river be determined before regulatory bodies set effluent discharge limits. It is also recommended that the water quality of water bodies draining pollution prone catchments be monitored regularly, besides just monitoring the discharge points.


      PubDate: 2016-03-25T19:31:49Z
       
  • Evaluation of Borehole Water Quality in Rural-Areas Of Northern Malawi:
           Case of Zombwe in Mzimba
    • Abstract: Publication date: Available online 22 March 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): O. Nakoma, R.C.G. Chidya, S. Matamula, C.B.J. Chawinga
      Many people in developing countries in Sub-Saharan region generally rely on groundwater sources for potable water. Despite increased demand for safe drinking water over the years, its availability, quality, and supply remains a challenge in Malawi and other developing countries. This study was conducted to evaluate quality of water from boreholes (n=20) in Zombwe Extension Planning Area (EPA), Mzimba in Northern Malawi to ascertain their safety. Desktop studies and participatory approaches were employed to assess the socio-economic activities and water supply regime in the study areas. Water samples were analyzed for selected physico-chemical parameters: pH, conductivity (EC), turbidity, water temperature, nitrate ( NO 3 − ), magnesium (Mg), calcium (Ca), zinc (Zn), fluoride (F-), and sulphate ( SO 4 2 − ). In-situ and laboratory analyses were carried out using portable meters and standard procedures. The results were compared with national standards (Malawi Bureau of Standards - MBS) for boreholes and shallow well water quality and international standards (World Health Organization - WHO) for drinking water. The following ranges were obtained for all the sites: pH (6.00-7.80), EC (437-3128 μS/cm), turbidity (0.10-5.80 NTU), water temperature (27.0-30.60 °C), NO 3 − (0.30-30.00 mg/L), F- (0.10-8.10 mg/L), Mg (31.00-91.00 mg/L), Ca (20.00-197.10 mg/L), SO 4 2 − (10.20-190 mg/L), Fe (0.10-3.60 mg/L) and Zn (0.00-5.10 mg/L). In general, several sites (>80%, n=20) complied with both MBS and WHO limits. No significant differences (p>0.05) was observed for most parameters (>65%, n=11). Generally, levels of groundwater pollution were not significant in the area despite some parameters such as Ca and SO 4 2 − showing higher levels at other sites. The study area registered groundwater sources with very hard water (244.60-757.80 mg/L CaCO3) suggesting contamination of groundwater probably due to mineralization influenced by underground rock material. Further studies are needed to ascertain the groundwater quality and health effects of microbiological and other parameters in the area. There is also a need for regular monitoring of the water sources for comparative analyses and spatio-temporal variation assessment.


      PubDate: 2016-03-25T19:31:49Z
       
  • Application of satellite products and hydrological modeling for flood
           early warning
    • Abstract: Publication date: Available online 19 March 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Sifan A. Koriche, Tom H.M. Rientjes
      Floods have caused devastating impacts to the environment and society in Awash River Basin, Ethiopia. Since flooding events are frequent, this marks the need to develop tools for flood early warning. In this study, we propose a satellite based flood index to identify the runoff source areas that largely contribute to extreme runoff production and floods in the basin. Satellite based products used for development of the flood index are CMORPH (0.250 by 0.250, daily) product for calculation of the Standard Precipitation Index (SPI) and a SRTM digital elevation model for calculation of the Topographic Wetness Index (TWI). Other satellite products used in this study are for rainfall-runoff modelling to represent rainfall, potential evapotranspiration, vegetation cover and topography. Results of the study show that assessment of spatial and temporal rainfall variability by satellite products may well serve in flood early warning. Preliminary findings on effectiveness of the flood index developed in this study indicate that the index is well suited for flood early warning. The index combines SPI and TWI, and preliminary results illustrate the spatial distribution of likely runoff source areas that cause floods in flood prone areas.


      PubDate: 2016-03-20T19:09:57Z
       
  • The hydrology of sand rivers in Zimbabwe and the use of remote sensing to
           assess their level of saturation
    • Abstract: Publication date: Available online 10 March 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): S.C. Mpala, A.S. Gagnon, M.G. Mansell, S.W. Hussey
      Sand rivers are ephemeral watercourses containing sand that are occasionally flooded with rainwater runoff during the rainy season. Although the riverbed appears dry for most of the year, there is perennial groundwater flow within the sand. This water flowing beneath the surface is a valuable resource for local communities; nonetheless our understanding of such river systems is limited. Hence, this paper aims to improve our understanding of the hydrology of sand rivers and to examine the potential use of remote sensing to detect the presence of water in the sand. The relationship between rainfall events and changes in the water level of two sand rivers in the Matabeleland South Province of Zimbabwe was investigated. A lagged relationship was observed for the Manzamnyama River but for the Shashani River the relationship was seen only when considering cumulative rainfall events. The comparison of the modelled flow as simulated by a water balance model with observations revealed the important influence of the effective sediment depth on the recharge and recession of the alluvial channels in addition to the length of the channel. The possibility of detecting water in the alluvial sands was investigated using remote sensing. During the wet season, optical images showed that the presence of water on the riverbed was associated with a smooth signal, as it tends to reflect the incident radiation. A chronological analysis of radar images for different months of the year demonstrates that it is possible to detect the presence of water in the sand rivers. These results are a first step towards the development of a methodology that would aim to use remote sensing to help reducing survey costs by guiding exploratory activities to areas showing signs of water abstraction potential.


      PubDate: 2016-03-11T18:23:31Z
       
  • How is water availability related to the land use and morphology of an
           inland valley wetland in Kenya?
    • Abstract: Publication date: Available online 10 March 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Beate Böhme, Mathias Becker, Bernd Diekkrüger, Gerd Förch
      Small inland valley wetlands contribute substantially to the livelihoods of rural communities in East Africa. Their conversion into farmland is driven by water availability. We quantified spatial-temporal dynamics of water availability in a headwater wetland in the humid zone of Kenya. Climatic conditions, soil moisture contents, groundwater levels and discharge data were monitored. A land-use map and a digital elevation model of the valley bottom were created to relate variations in soil moisture to dominant land uses and valley morphology. Upland crops occupied about a third of the wetland area, while approximately a quarter of the wet, central part of the valley bottom was designated for flood-tolerant taro, grown either by itself or in association or in rotation with upland crops. Finally, natural vegetation was found in 3% of the mapped area, mainly in sections with nearpermanent soil saturation. The HBV rainfall-runoff model's overestimation of stream discharge during the long dry season of the hydrological year 2010/2011 can be explained by the strong seasonal impact of water abstraction on the wetland's water balance. Our study vividly demonstrates the necessity of multi-method approaches for assessing the impact of management practices on water availability in valley bottom wetlands in East Africa.


      PubDate: 2016-03-11T18:23:31Z
       
  • Land use/land cover change and implications for ecosystems services in the
           Likangala River Catchment, Malawi
    • Abstract: Publication date: Available online 10 March 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Deepa Pullanikkatil, Lobina G. Palamuleni, Tabukeli M. Ruhiiga
      Likangala River catchment in Zomba District of Southern Malawi is important for water resources, agriculture and provides many ecosystem services. Provisioning ecosystem services accrued by the populations within the catchment include water, fish, medicinal plants and timber among others. In spite of its importance, the River catchment is under threat from anthropogenic activities and land use change. This paper studies land uses and land cover change in the catchment and how the changes have impacted on the ecosystem services. Landsat 5 and 8 images (1984, 1994, 2005 and 2013) were used to map land cover change and subsequent inventorying of provisioning ecosystem services. Participatory Geographic Information Systems and Focus group discussions were conducted to identify provisioning ecosystems services that communities benefit from the catchment and indicate these on the map. Post classification comparisons indicate that since 1984, there has been a decline in woodlands from 135.3km2 in 1984 to 15.5km2 in 2013 while urban areas increased from 9.8km2 to 23.8km2 in 2013. Communities indicated that provisioning ecosystems services such as forest products, wild animals and fruits and medicinal plants have been declining over the years. In addition, evidence of catchment degradation through waste disposal, illegal sand mining, deforestation and farming on marginal lands were observed. Population growth, urbanization and demand for agricultural lands have contributed to this land use and land cover change. The study suggests addressing catchment degradation through integrated method where an ecosystems approach is used. Thus, both the proximate and underlying driving factors of land-use and land cover change need to be addressed in order to sustainably reduce ecosystem degradation.


      PubDate: 2016-03-11T18:23:31Z
       
  • Water supply dynamics and quality of alternative water sources in
           low-income areas of Lilongwe City, Malawi
    • Abstract: Publication date: Available online 10 March 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Russel C.G. Chidya, Wapulumuka O. Mulwafu, S. Banda
      Recent studies in many developing countries have shown the emergence of Small Scale Independent Providers (SSIPs) in low-income areas (LIAs) as practical alternatives to water utilities. This study explored supply dynamics and quality of alternative water sources in four LIAs of Lilongwe City in Malawi using qualitative and quantitative methods. Household-level surveys (n=120) and transect walks were employed to determine the socio-economic activities in the areas. One-on-one discussions were made with water source owners (SSIPs) (n=24). Data on policy and institutional frameworks was collected through desktop study and Key Informant Interviews (n=25). Quality of the water sources (shallow wells and boreholes) was determined by collecting grab samples (n=24) in triplicate using 500 mL bottles. Selected physico-chemical and microbiological parameters were measured: pH, EC, TDS, turbidity, water temperature, salinity, K, Na, Ca, Mg, Cl-, F-, NO3 -, alkalinity, water hardness, Feacal coliform (FC) and Faecal Streptococci (FS) bacteria. Water quality data was compared with Malawi Bureau of Standards (MBS) and World Health Organization (WHO) guidelines for drinking water. Shallow wells were reported (65%, n=120) to be the main source of water for household use in all areas. Some policies like prohibition of boreholes and shallow wells in City locations were in conflict with other provisions of water supply, sanitation and housing. High levels of FC (0-2100 cfu/100 mL) and FS (0-1490 cfu/100 mL) at several sites (>90%, n=24) suggest water contamination likely to impact on human health. This calls for upgrading and recognition of the water sources for improved water service delivery.


      PubDate: 2016-03-11T18:23:31Z
       
  • Estimation of Groundwater Vulnerability to Pollution based on DRASTIC in
           the Niipele sub-Basin of the Cuvelai Etosha Basin, Namibia
    • Abstract: Publication date: Available online 23 January 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): J.T. Hamutoko, H. Wanke, H.J. Voigt
      Surface water is a scarce resource in Namibia with about sixty percent of Namibia’s population dependent on groundwater for drinking purposes. With increasing population, the country faces water challenges and thus groundwater resources need to be managed properly. One important aspect of Integrated Water Resources Management is the protection of water resources, including protection of groundwater from contamination and over-exploitation. This study explores vulnerability mapping as a basic tool for protecting groundwater resources from pollution. It estimates groundwater vulnerability to pollution in the upper Niipele sub-basin of the Cuvelai-Etosha in Northern Namibia using the DRASTIC index. The DRASTIC index uses GIS to estimate groundwater vulnerability by overlaying different spatially referenced hydrogeological parameters that affect groundwater contamination. The study assesses the discontinuous perched aquifer (KDP) and the Ohangwena multi-layered aquifer 1 (KOH-1). For perched aquifers, point data was regionalized by a hydrotope approach whereas for KOH-1 aquifer, inverse distance weighting was used. The hydrotope approach categorized different parts of the hydrogeological system with similar properties into five hydrotopes. The result suggests that the discontinuous perched aquifers are more vulnerable than Ohangwena multi-layered aquifer 1. This implies that vulnerability increases with decreasing depth to water table because contaminants have short travel time to reach the aquifer when they are introduced on land surface. The nitrate concentration ranges between 2 to 288 mg/l in perched aquifers while in Ohangwena multi-layered aquifer 1, it ranges between 1 to 133 mg/l. It was observed that perched aquifers have high nitrate concentrations than Ohangwena 1 aquifer, which correlates well with the vulnerability results.


      PubDate: 2016-01-25T11:18:14Z
       
 
 
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