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Journal of Earth System Science
Journal Prestige (SJR): 0.366
Citation Impact (citeScore): 1
Number of Followers: 49  

  This is an Open Access Journal Open Access journal
ISSN (Print) 0253-4126 - ISSN (Online) 0973-774X
Published by Springer-Verlag Homepage  [2352 journals]
  • Establishment of digital 3D map based on discrete elevation point data
           measured in the field

    • Authors: Aimin Li; Zhiwen Han; Caiyun Guo; Shuai Zhong
      Abstract: This study established a survey zone digital elevation model (DEM) using highly precise and regularly updated three-dimensional coordinates of the surface of barchan dunes using CASS9.0 software. Two contour plots were drawn, one for the entire survey zone drawn with a contour interval of 0.005 m and one for an individual sand dune drawn with a contour interval of 0.001 m. ArcMap10 was used to define the projection of the created contour lines in DWG format and export the data into shape files to enable the creation of a triangulated irregular network (TIN). Next, TIN data was converted into raster data to facilitate our analysis and data processing. We created the final TIN by using an additional smoothing processing on the desired area that had been clipped out. We added the TIN data to the ArcScene module to establish the final 3D numerical model of barchan dunes. This model extracts and analyzes the changes in the characteristic parameters of the barchan dune as its topography changes in real time so researchers can visualize dune migration and evolution. Their understanding is enhanced by comparing and superposing the various 3D dune models on different days.
      PubDate: 2019-01-19
      DOI: 10.1007/s12040-018-1046-9
      Issue No: Vol. 128, No. 2 (2019)
       
  • Shear creep characteristics of weak carbonaceous shale in thick layered
           Permian limestone, southwestern China

    • Authors: Sainan Zhu; Yueping Yin; Bin Li; Yingjuan Wei
      Abstract: Several weak intercalations of carbonaceous shale, which are commonly developed in the Permian thick limestone strata in Wulong County, Chongqing, southwestern China, form a structure of alternating layers of soft and hard rocks, which control the stability of massive layered rockslides. We focus on the Permian carbonaceous shale and analyse its mineral composition, microstructure and shear creep characteristics during the three evolutionary stages. The analysis results indicate the following: (i) During the evolutionary process of the carbonaceous shale, the microstructure changed from compact to loose, and the clay mineral content gradually increased from less than 5% in the original soft rock to 5–10% in the interlayer shear zone, and finally to greater than 10% in the sliding zone. (ii) Under the identical shear stress, the creep displacement and rate gradually increase nonlinearly. Under the identical normal stress, the long-term shear strength gradually decreases, and the drop in cohesion is greater than the internal friction angle. (iii) We established an improved Burgers nonlinear damage creep model, which fully reflected the creep deformation process of the carbonaceous shale. The fitting curve of the model matched the experimental results well.
      PubDate: 2019-01-19
      DOI: 10.1007/s12040-018-1051-z
      Issue No: Vol. 128, No. 2 (2019)
       
  • Mapping of groundwater spring potential zone using geospatial techniques
           in the Central Nepal Himalayas: A case example of Melamchi–Larke area

    • Authors: Motilal Ghimire; Prem Sagar Chapagain; Shova Shrestha
      Abstract: Studies assessing the groundwater spring potential in the Himalayan mountain slopes are very important for sustainable water resources management and build climate resilience in mountains, but such studies are few in the Himalayas. Hence, this paper attempts to identify the groundwater spring potential zone in the Central Himalayas of Nepal. About 412 groundwater springs were surveyed, which were mainly originated from the weathered, jointed or fractured rock aquifers in the high-grade metamorphosed rocks. Eleven influencing factors, viz., altitude, slope gradient, slope shape, relative relief, flow accumulation, drainage density, geology, lineament density, land use and vegetation density were considered in assessing the groundwater spring potential using the weight of evidence method. Weight indicating the probability of groundwater spring occurrence on multiple classes of each factor was calculated and finally summed up to determine the groundwater spring potential. Gentle slope, low relative relief, high flow accumulation, north- and east-facing slopes, denser lineament density, altitude class of 1500–2500 m, high vegetation density, and forest demonstrated a higher likelihood of spring occurrence. Validation of the groundwater spring potential map was successful, which implies the method can be replicated in a similar biophysical environment, where the hydrogeological or geophysical surveyed data is not available.
      PubDate: 2019-01-19
      DOI: 10.1007/s12040-018-1048-7
      Issue No: Vol. 128, No. 2 (2019)
       
  • Groundwater quality in a semi-arid region of India: Suitability for
           drinking, agriculture and fluoride exposure risk

    • Authors: Tirumalesh Keesari; Uday Kumar Sinha; Pradeep Kamaraj; Diana Anoubam Sharma
      Abstract: Fluoride exposure through consumption of drinking water was studied in a heavily industrialised area and suitable measures were suggested to control the fluorosis risk to residents. Groundwater quality conforms to World Health Organization (WHO) criterion for drinking except for fluoride and is also suitable for irrigation. Fluoride concentration ranges from 0.1 to 4.4 mg/l and 39% of the total samples measured were found to be contaminated as per WHO limits (1.5 mg/l). The fluoride intake through drinking water was calculated to be 0.10 mg/kg/d for infants, 0.09 mg/kg/d for children and 0.05 mg/kg/d for adults with a corresponding exposure dose exceeding 2.1, 1.9 and 1.1 times for infants, children and adults, respectively, compared to the minimum risk value of 0.05 mg/kg/d. The fluorosis risk map indicates that with a few exceptions of some western and northwestern parts, the entire study area is prone to fluorosis and the highest being in the south central part. The fluoride exposure dose suggests the risk of mottled enamel among residents if untreated groundwater is provided for drinking for a long time. Considering the hydrogeological setup of this region, various amelioration methods to help mitigate the ill effects of high fluoride were evaluated and better nutrition containing calcium and vitamin C was found to be the most effective and viable option.
      PubDate: 2019-01-19
      DOI: 10.1007/s12040-018-1049-6
      Issue No: Vol. 128, No. 2 (2019)
       
  • Co-seismic grace gravity-based 11-layered 3-D thrust fault model for the
           Sumatra earthquake 2004

    • Authors: Rambhatla G Sastry; Mahendra Kumar Sonker
      Abstract: Our co-seismic Gravity Recovery and Climate Experiment gravity data (level 2 ‘RL_05’ data product ‘GX-OG-_2-GSM) for the Sumatra earthquake 2004 is obtained by differencing monthly gravity field average for November 2004 from that of January 2005 and band-pass filtering ( \(17{-}30^{\circ }\) and orders) in the spectral domain. Here, we propose a 11-layered three-dimensional (3-D) thrust fault gravity model based on different co-seismic rupture models in the literature. It honours co-seismic deformation of the ocean surface, ocean bottom and subsurface earth medium, different earthquake parameters and hypocentre information ( \({\sim }35\)  km below mean sea level). Our forward gravity response matches well with the observed gravity (RMS error of \(0.06257\,\upmu \hbox {gal}\) (6.26%)) data and our model allowed an independent computation of rupture length, instantaneous velocity, average seismic moment and momentum, which are, respectively, 1560 km, 2.9 km/s, \(4.53\times 10^{22 }\,\hbox {N}\,\hbox {m}\) and \( 9.7\times 10^{17}\,\hbox {kg}\,\hbox {m/s}\) . These parameters fairly agree with those in the literature. The computed momentum indeed corresponds to an area pulse ( \(9.7\times 10^{17}\,\hbox {kg}\,\hbox {m/s}\) ) at ocean bottom that led to a tsunami generation. Thus, the proposed multi-layered 3-D gravity model in traditional fashion fully accounts for co-seismic gravity signal of the Sumatra earthquake 2004.
      PubDate: 2019-01-19
      DOI: 10.1007/s12040-018-1050-0
      Issue No: Vol. 128, No. 2 (2019)
       
  • Investigating suspended-sediment transport in a shallow lake using a
           three-dimensional hydrodynamic and sediment model

    • Authors: Wen-Cheng Liu; Hong-Ming Liu; Chih-Yu Chiu
      Abstract: A three-dimensional, unstructured-grid hydrodynamic and suspended-sediment transport model was developed to simulate the temporal and spatial variations of suspended sediment and was applied to the subtropical subalpine Tsuei-Feng Lake (TFL) of Taiwan. The model was validated with measured water level and suspended-sediment concentration in 2009, 2010 and 2011. The overall model simulation results are in quantitative agreement with the observational data. The validated model was then applied to explore the most important parameter that affects the suspended-sediment concentration and to investigate the effect of wind stress on the mean current and suspended-sediment distribution in this shallow lake. Modelling results of the sensitivity analysis revealed that the settling velocity is a crucial parameter and the erosion rate is less important in the suspended-sediment transport model. Remarkable lake circulation was found based on the strength of wind speed and wind direction. A strong wind would result in a higher mean current in the top layer and suspended-sediment distribution in the top and bottom layers. This study demonstrated that wind stress played a significant influence on mean circulation and suspended-sediment transport in a shallow lake.
      PubDate: 2019-01-19
      DOI: 10.1007/s12040-018-1063-8
      Issue No: Vol. 128, No. 2 (2019)
       
  • Propagation and coalescence of en-echelon cracks under a far-field tensile
           stress regime: An experimental study

    • Authors: Nilanjana Ghosh; Kalyanbrata Hatui; Anupam Chattopadhyay
      Abstract: Experiments were carried out to observe the variation in propagation and linkage of parallel en-echelon cracks with varying orientation of the crack array and different relative position of the cracks within the array in an extensional regime. Two-layered analogue model, with a basal layer of pitch overlain by a layer of kaolin paste was used in the experiments. En-echelon cracks were pre-cut within the kaolin layer maintaining specific geometrical parameters of the cracks (e.g., length, centre spacing, separation) in such a manner that there was a weak (though not negligible) local tip-induced stress favouring curvature of adjacent crack tips towards one another. The results obtained were matched with natural pattern of linkage of veins, rift basins and spreading ridges, as described in the relevant literature. The experimental results showed that the final pattern of linkage between the cracks was a result of initial deflection of crack tip from its plane due to combined effect of local and far-field stress. When the deflection of tip from the crack plane was between \(0{^{\circ }}\) to \(45{^{\circ }}\) , a ‘tip to wall’ linkage took place between adjacent cracks isolating a rhombohedral area in the interaction zone. The resultant structure could be geometrically comparable to a micro-plate-like structure isolated due to linkage of ridge segments initially forming an overlapping spreading centre (OSC). When the deflection of tip from the crack plane was greater than \(45{^{\circ }}\) , a ‘tip to tip’ linkage between adjacent cracks took place resulting in a structure similar to a transform fault between spreading ridges and or rift basins. When effect of the remote stress opposed the tip induced stress, no linkage took place between the adjacent cracks, and finally the tips propagated straight along a plane perpendicular to the remote extension direction.
      PubDate: 2019-01-16
      DOI: 10.1007/s12040-018-1056-7
      Issue No: Vol. 128, No. 2 (2019)
       
  • Fractal dimension analysis for seismicity spatial and temporal
           distribution in the circum-Pacific seismic belt

    • Authors: Lirong Yin; Xiaolu Li; Wenfeng Zheng; Zhengtong Yin; Lihong Song; Lijun Ge; Qingchuan Zeng
      Abstract: In this study, we present the fractal characteristics of the spatio-temporal sequence for seismic activity in the circum-Pacific seismic belt and vicinity regions, which is one of the most active seismic zones worldwide. We select the seismic dataset with magnitude \(M\ge 4.4\) in the circum-Pacific seismic belt region and its vicinity from 1900–2015 as the objects. Based on the methods of capacity dimension and information dimension, using \(\hbox {ln}(1/\delta )\) – \(\hbox {ln }N(\delta )\) of the relationship to evaluate and explain, the results show that (1) in the circum-Pacific seismic belt and the surrounding areas, for the seismic activity with magnitude \(M\ge 4.4\) , the time series dimension is 0.63, the spatial distribution dimension is 0.52 and they have fractal structure. (2) For the earthquakes with \(M\ge 7.0\) , the time series dimension increases greatly, which indicates that the cluster characteristics in time is greatly reduced. And the earthquakes with magnitude \(7.0 \ge M \ge 4.4\) have significant impact on the characterized by clustering in time in the study region. (3) There is significant fractal structure at spatio-temporal distribution of earthquakes in the circum-Pacific seismic belt. It reveals the tectonic movements keep continuous, obvious anisotropism characteristic of geological structure and the distribution of surface stress field is spatio-temporal heterogeneity in the study area.
      PubDate: 2019-01-04
      DOI: 10.1007/s12040-018-1040-2
      Issue No: Vol. 128, No. 1 (2019)
       
  • Wyrtki Jets: Role of intraseasonal forcing

    • Authors: S Prerna; Abhisek Chatterjee; A Mukherjee; M Ravichandran; S S C Shenoi
      Abstract: Direct current measurements observed from the acoustic Doppler current profilers in the equatorial Indian Ocean (EIO) and solutions from an ocean general circulation model are investigated to understand the dynamics of the Wyrtki jet. These jets are usually described as semiannual direct wind forced zonal currents along the central and eastern EIO. We show that both, spring and fall, Wyrtki jets show predominant semiannual spectral peaks, but significant intraseasonal energy is evident during spring in the central and eastern EIO. We find that for the semiannual band, there is a strong spectral coherence between the overlying winds and the currents in the central EIO, but no coherency is observed in the eastern part of the EIO. Moreover, for the intraseasonal band, strong coherency between the winds and currents is evident. During spring, intraseasonal currents induced by the Madden–Julian oscillation (MJO) superimpose constructively with semiannual currents and thus intensify the strength of the spring Wyrtki jet. Also, the atmospheric intraseasonal variability accounts for the interannual variabilities observed in spring Wyrtki jets.
      PubDate: 2019-01-04
      DOI: 10.1007/s12040-018-1042-0
      Issue No: Vol. 128, No. 1 (2019)
       
  • Seasonal variability of sea-surface temperature fronts associated with
           large marine ecosystems in the north Indian Ocean

    • Authors: Kankan Sarkar; S G Aparna; Shrikant Dora; D Shankar
      Abstract: We use 14 years of satellite-derived sea-surface temperature (SST) data to compute a monthly frontal probability index (FPI) to determine the existence of a front in a pixel. A persistent SST front is deemed to exist if the FPI in a narrow region exceeds that in the surrounding ocean. We describe the seasonal variability of 17 persistent SST fronts (eight associated with the shelf-slope boundary and five with the mixing between different water masses) in the north Indian Ocean. Only weak fronts exist during a few months in the strong upwelling regimes off Somalia and Oman.
      PubDate: 2018-12-18
      DOI: 10.1007/s12040-018-1045-x
      Issue No: Vol. 128, No. 1 (2018)
       
  • The first record of active methane (cold) seep ecosystem associated with
           shallow methane hydrate from the Indian EEZ

    • Authors: A Mazumdar; P Dewangan; A Peketi; S Gullapalli; M S Kalpana; G P Naik; D Shetty; S Pujari; S P K Pillutla; V V Gaikwad; D Nazareth; N S Sangodkar; G Dakara; A Kumar; C K Mishra; P Singha; R Reddy
      Abstract: Here we report the discovery of cold-seep ecosystem and shallow methane hydrates (2–3 mbsf) associated with methane gas flares in the water column from the Indian EEZ for the first time. The seep-sites are located in the Krishna–Godavari (K–G) basin at water depths of 900–1800 m and are characterized by gas flares in the water-column images. The occurrence of methane gas hydrates at very shallow depths (2–3 mbsf) at some of the seep-sites is attributed to high methane flux and conducive P–T conditions, necessary for the stability of methane hydrate. Chemosymbiont bearing Bivalves (Vesicomidae, Mytilidae, Thyasiridae and Solemyidae families); Polychaetes (Siboglinidae family) and Gastropods (Provannidae family) are also identified from seep-sites.
      PubDate: 2018-12-17
      DOI: 10.1007/s12040-018-1044-y
      Issue No: Vol. 128, No. 1 (2018)
       
  • Geological, geochemical and Rb–Sr isotopic studies on tungsten
           mineralised Sewariya–Govindgarh granites of Delhi Fold Belt, Rajasthan,
           NW India

    • Authors: R Sivasubramaniam; Sundarrajan Vijay Anand; M S Pandian; S Balakrishnan
      Abstract: Neoproterozoic granites are widespread in the Delhi Fold Belt of the Aravalli craton, some of which are associated with tungsten mineralisation. In one such instance, the volcano-sedimentary sequence of Barotiya Group in the South Delhi Fold Belt is intruded by a pluton of biotite granite gneiss known as Sewariya Granite (SG) and later by stocks and dyke swarm of tourmaline leucogranite known as Govindgarh Granite (GG). GG magmatism was associated with wolframite mineralisation in hydrothermal quartz veins occurring along the sheared contact between SG pluton and Barotiya mica schist. SG pluton shows the evidence of ductile and brittle deformations, whereas GG is by and large undeformed. Apart from quartz and feldspars, SG contains biotite and muscovite, and GG contains muscovite, tourmaline and garnet. Although both SG and GG are peraluminous, SG has a wide range of \(\hbox {SiO}_{2}\) and narrow range of alkalis, and GG has a narrow range of \(\hbox {SiO}_{2}\) and a wide range of alkalis. REE (rare Earth elements) modelling shows that the parent magma of SG and GG was derived from partial melting at different crustal levels. Rb–Sr isotope data of GG yield a mineral isochron age of \(860\pm 7.4\,\hbox {Ma}\) which represent the time of igneous crystallisation and cooling of the granite to less than 400 \({^{\circ }}\) C.
      PubDate: 2018-12-17
      DOI: 10.1007/s12040-018-1034-0
      Issue No: Vol. 128, No. 1 (2018)
       
  • Arctic summer sea-ice seasonal simulation with a coupled model: Evaluation
           of mean features and biases

    • Authors: P P Saheed; Ashis K Mitra; Imranali M Momin; E N Rajagopal; Helene T Hewitt; Ann B Keen; Sean F Milton
      Abstract: Current state of the art weather/climate models are representation of the fully coupled aspects of the components of the earth system. Sea-ice is one of the most important components of these models. Simulation of sea-ice in these models is a challenging problem. In this study, evaluation of the hind-cast data of 14 boreal summer seasons with global coupled model HadGEM3 in its seasonal set-up has been performed over the Arctic region from \(9\mathrm{th}\) May start dates. Along with the biases of the sea-ice variables, related atmosphere and oceanic variables have also been examined. The model evaluation is focused on seasonal mean of sea-ice concentration, sea-ice thickness, ocean surface current, SST, ice-drift velocity and sea-ice extent. To diagnose the sea-ice biases, atmospheric variables like, 10 m wind, 2 m air temperature, sea-level pressure and ocean sub-surface temperatures were also examined. The sea-ice variables were compared with GIOMAS dataset. The atmospheric and the oceanic variables were compared with the ERA Interim and the ECMWF Ocean re-analysis (ORAP5) datasets, respectively. The model could simulate the sea-ice concentration and thickness patterns reasonably well in the Arctic Circle. However, both sea-ice concentration and thickness in the model are underestimated compared to observations. A positive (warm) bias is seen both in 2 m air temperature and SST, which are consistent with the negative sea-ice bias. Biases in ocean current and related ice drift are not related to biases in the atmospheric winds. The magnitude of the oceanic subsurface warm biases is seen to be gradually decreasing with depth, but consistent with sea-ice biases. These analyses indicate a possibility of deeper warm subsurface water in the western Arctic Ocean sector (Pacific and Atlantic exchanges) affecting the negative biases in the sea-ice at the surface. The model is able to simulate reasonably well the summer sea-ice melting process and its inter-annual variability, and has useable skill for application purpose.
      PubDate: 2018-12-11
      DOI: 10.1007/s12040-018-1043-z
      Issue No: Vol. 128, No. 1 (2018)
       
  • Mapping magnetic lineaments and subsurface basement beneath parts of Lower
           Benue Trough (LBT), Nigeria: Insights from integrating gravity, magnetic
           and geologic data

    • Authors: Mukaila Abdullahi; Upendra K Singh; Ravi Roshan
      Abstract: In this study, we present the analysis of the aeromagnetic data of parts of the Lower Benue Trough. Lineament analysis of the aeromagnetic data demonstrated four tectonic trends of the basement terrain. The lineaments are in the northeast to southwest (NE–SW), east, northeast to west, southwest (ENE–WSW), north to south (N–S), and east, southeast to west, northwest (ESE–WNW) directions. The NE–SW and ENE–WSW are the most dominant whereas the N–S and ESE–WNW are the minor trends. The estimated magnetic basement using spectral analysis vary between 3.5 and 5 km and the shallow magnetic sources (depth to top of intrusions) vary between 0.24 and 1.2 km. The result of the basement estimation from the magnetic data is comparable with the previous results from other studies as well as with the basement depth estimated from the gravity data of part of the present study area are incorporated in the study. From the gravity data, we identified sub-basin around Makurdi and basement of the sedimentary basin (5 km) is estimated using GPSO algorithm and Oasis Montaj (Geosoft).
      PubDate: 2018-12-11
      DOI: 10.1007/s12040-018-1038-9
      Issue No: Vol. 128, No. 1 (2018)
       
  • Holocene environmental changes in Red River delta, Vietnam as inferred
           from the stable carbon isotopes and C/N ratios

    • Authors: Nguyen Tai Tue; Dang Minh Quan; Pham Thao Nguyen; Luu Viet Dung; Tran Dang Quy; Mai Trong Nhuan
      Abstract: The present study applied stable carbon isotopes, C/N ratios, and sedimentological indicators to reconstruct environmental changes during Holocene and to test the hypothesis that \(\updelta ^{13}\hbox {C}\) and C/N ratios are accurate proxies of sea level change in the Red River delta (RRD), Vietnam. A 36 m long sediment core was mechanically drilled in the wave-dominated region of the RRD. The covariation of lithological characteristics, sediment grain-size distribution and geochemical proxies (LOI, TOC, C/N, \(\updelta ^{13}\hbox {C}\) ) suggested that the sediment core could be divided into six depositional environments, consisting of sub- and inter-tidal flats (formed before 8860 cal. year BP), shelf-prodelta, delta front slope (formed from 8860 to 2290 cal. year BP), delta front platform, tidal flat, and flood plain (from 2290 to 0 cal. year BP). Covariation of \(\updelta ^{13}\hbox {C}\) and C/N ratios in the sediment core allowed for tracing the origin of sedimentary organic carbon, which shifted from the dominance of mangroves and C3 plants at the sub- and inter-tidal flats to marine phytoplankton at the shelf-prodelta and delta front slope. The sedimentary sources of the delta front platform, tidal flat and flood plain were a mixture of phytoplankton and C3 plants, with the later source being dominant.
      PubDate: 2018-12-10
      DOI: 10.1007/s12040-018-1041-1
      Issue No: Vol. 128, No. 1 (2018)
       
  • Zebra layers and palaeoenvironment of Late Miocene Stratum in the Linxia
           Basin, northwestern China

    • Authors: Xiuqing Nian; Xiuming Liu; Hui Guo; Zhi Liu; Bin Lü; Fengqing Han
      Abstract: Miocene strata in the Linxia Basin (Gansu, China) are usually interpreted as lacustrine sediments. However, the red–grey inter-beds known as ‘Zebra layers’ commonly tilt with respect to the terrain on the side slopes of the modern valley, which may be due to mantling palaeotopography (similar to aeolian loess). The anisotropy of magnetic susceptibility, which reflects the original arrangement of magnetic particles in sediments, was applied to investigate this phenomenon. The results showed that the tilting of the inter-beds in the side slope was due to mantle palaeotopography rather than soil creep, and that they were not deposited in a subaqueous environment. The grain sizes of sediments showed similar features as aeolian loess. We speculate that Miocene sediments were deposited by mantling the palaeotopography where aeolian materials accumulated. After deposition, flowing water submerged these strata, which caused the side slope to become gradually thinner from top to bottom and stirred the magnetic particles in these sediments. The grey colour of the Zebra layers may not be original, as it may be due to waterlogging and deoxidation after deposition; finally, when the iron oxides in these sediments were transformed or removed, their colours became grey. The formation of Zebra layers indicates that the Late Miocene palaeoenvironment of northwestern China was similar to that in which Quaternary aeolian loess was deposited.
      PubDate: 2018-12-01
      DOI: 10.1007/s12040-018-1031-3
      Issue No: Vol. 128, No. 1 (2018)
       
  • Analysis of deformation characteristics and stability mechanisms of
           typical landslide mass based on the field monitoring in the Three Gorges
           Reservoir, China

    • Authors: Yonggang Zhang; Shuyun Zhu; Weiqiang Zhang; Hui Liu
      Abstract: Based on a large number of data including GPS monitoring of surface deformation and inclinometer monitoring of internal deformation over 7 years, we find that the displacement of a typical landslide mass has the stepped evolution characteristics as: the variation of the reservoir water level under the different years and months in the Three Gorges Reservoir and the deformation of landslide mass surges in the flood season. On the contrary, the deformation of landslide mass slows down in the non-flood season. Especially, in 2007, 2009 and 2011, the fluctuation of the surface monitoring displacement is more intense than that in the other years. In addition, the whole landslide mass has a characteristic of the trial-type sliding. The surface displacement is greater than the internal displacement. Based on that, deformation characteristics, stability mechanisms and the influencing factors of landslide mass are studied deeply. The results show that the drawdown of the water level of the Three Gorges Reservoir region is the main controlling factor of the deformation of the landslide mass. The results of the study have a significant value of reference on the stability analysis of landslide mass under the similar engineering geological conditions.
      PubDate: 2018-12-01
      DOI: 10.1007/s12040-018-1036-y
      Issue No: Vol. 128, No. 1 (2018)
       
  • Multi-year satellite observations of tropospheric $$\hbox {NO}_{2}$$ NO 2
           concentrations over the Indian region

    • Authors: M K Madhav Haridas; Biswadip Gharai; Subin Jose; T Prajesh
      Abstract: An assessment of satellite-derived long-term tropospheric nitrogen dioxide ( \(\hbox {NO}_{2})\) data is performed over the Indian region and their implications on the regional air quality are discussed. The Indo-Gangetic plain (IGP) shows an increasing trend in \(\hbox {NO}_{2}\) of the order of \(3\times 10^{13}\hbox { mol/cm}^{2}/\hbox {yr}\) . The pixel-wise (0.25 km) trend for the period 2005–2014 reveals various regions having increased rates of pollution over the study period. Further, the mean seasonal concentrations of \(\hbox {NO}_{2}\) are segregated for different parts of the country including oceanic regions and the trends are brought out. The highest rate of increase of tropospheric \(\hbox {NO}_{2}\,(2\times 10^{14}\,\hbox {mol}/\hbox {cm}^{2}/\hbox {yr}\) ) is seen around coal mining areas and certain industrial areas such as ports and thermal power stations. Using the data spanning 10 years, the wavelet analysis is carried out to study the influence of semi-annual oscillations (SAO) on trace gas concentrations in different parts of the country. The study reveals that the SAO are stronger in the northern parts of India, including IGP and western India, whereas South India and oceanic regions are having very low SAO component and strong annual oscillation component.
      PubDate: 2018-12-01
      DOI: 10.1007/s12040-018-1032-2
      Issue No: Vol. 128, No. 1 (2018)
       
  • Grain-size distribution of surface sediments of climbing and falling dunes
           in the Zedang valley of the Yarlung Zangbo River, southern Tibetan plateau
           

    • Authors: Jiaqiong Zhang; Chunlai Zhang; Qing Li; Xinghui Pan
      Abstract: Climbing and falling dunes are widespread in the wide valleys of the middle reaches of the Yarlung Zangbo River. Along a sampling transect running from northeast to southwest through 10 climbing dunes and two falling dunes in the Langsailing area, the surface sediments were sampled to analyse the grain-size characteristics, to clarify the transport pattern of particles with different grain sizes, and to discuss the effects of terrain factors including dune slope, mountain slope, elevation and transport distance to sand transport. Sand dunes on both sides of the ridge are mainly transverse dunes. Fine and medium sands were the main particles, with few very fine and coarse particles in the surface sediments. Particles \({>}4.00\varPhi \) were blown upslope by suspension, particles \(1.00{-}4.00\varPhi \) were mainly transported upslope by saltation with opposite change tendency, and particles \({<}1.00\varPhi \) mainly moved by creep were found almost exclusively at the bottom of the slopes. As terrain factors, elevation and transport distance were more important factors influencing the distribution of grain size and particle fraction on dunes. Local winds observation might be helpful for the transport mechanism study of particles on climbing and falling dunes, while the wind data from nearby weather station was hardly helpful.
      PubDate: 2018-12-01
      DOI: 10.1007/s12040-018-1030-4
      Issue No: Vol. 128, No. 1 (2018)
       
  • Generalised extreme value model with cyclic covariate
           structure for analysis of non-stationary hydrometeorological extremes
           

    • Authors: R S Jagtap; V K Gedam; Mohan M Kale
      Abstract: Studies carried out recently on hydrometeorological extremes report the evidence of non-stationarity induced by potential long-term climatic fluctuations and anthropogenic factors. A critical examination of the stationarity assumption has been carried out and a non-stationary generalised extreme value model with cyclic covariate structure for modelling magnitude and variation of data series with some degrees of correlation for real-world applications is proposed. Interestingly, the sinusoidal function with periodicity around 30 yr has been derived as a suitable covariate structure to deal with the ambiguous nature of temporal trends and this could possibly be linked to ‘Sun cycles’. It has adequately explained the cyclic patterns recognised in the annual rainfall which are helpful for realistic estimation of quantiles. Various diagnostic plots and statistics support the usefulness of the proposed covariate structure to tackle potential non-stationarities in the data characterising extreme events in various fields such as hydrology, environment, finance, etc.
      PubDate: 2018-12-01
      DOI: 10.1007/s12040-018-1033-1
      Issue No: Vol. 128, No. 1 (2018)
       
 
 
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Heriot-Watt University
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