Assessing Groundwater Resource Vulnerability by Coupling GIS-Based DRASTIC and Solute Transport Model in Ajmer District,Rajasthan

Groundwater aquifer vulnerability has been assessed by incorporating the major geological and hydrogeological factors that affect and control the groundwater contamination using GIS-based DRASTIC model along with solute transport modeling. This work demonstrates the potential of GIS to derive a vulnerability map by overlying various spatially referenced digital data layers (i.e., depth to water, net recharge, aquifer media, soil media, topography, the impact of vadose zone and hydraulic conductivity) that portrays cumulative aquifer sensitivity ratings in Kishangarh, Rajasthan. It provides a relative indication of groundwater aquifer vulnerability to contamination. The soil moisture flow and solute transport regimes of the vadose zone associated with specific hydrogeological conditions play a crucial role in pollution risk assessment of the underlying groundwater resources. An effort has been made to map the vulnerability of shallow groundwater to surface pollutants of thestudy area, using soil moisture flow and contaminant transport modeling. The classical advection-dispersion equation coupled with Richard’s equation is numerically simulated at different point locations for assessing the intrinsic vulnerability of the valley. The role of soil type, slope, and the land-use cover is considered for estimating the transient flux at the top boundary from daily precipitation and evapotranspiration data of the study area. The time required by the solute peak to travel from the surface to the groundwater table at the bottom of the soil profile is considered as an indicator of avulnerability index. Results show a high vulnerability in the southern region, whereas low vulnerability is observed in the northeast and northern parts. The results have recognized four aquifer vulnerability zones based on DRASTIC vulnerability index (DVI), which ranged from 45 to 178. It has been deduced that approximately 18, 25, 34, and 23% of the area lies in negligible, low, medium and high vulnerability zones, respectively. The study may assist in decision making related to theplanning of industrial locations and the sustainable water resources development of the selected semi-arid area.     

Studies of scintillations and TEC variations with GPS satellite links together with soil radon anomalies preceding Nepal earthquakes of April–May 2015

Natural Hazards - Ionospheric effects like scintillations and anomalous variations in total electron content (TEC) monitored with Global Positioning System (GPS) satellites of L1 frequency over...     

Multiwavelength Observations of Supersonic Plasma Blob Triggered by Reconnection-Generated Velocity Pulse in AR10808

Using multi-wavelength observations of Solar and Heliospheric Observatory (SoHO)/Michelson Doppler Imager (MDI), Transition Region and Coronal Explorer (TRACE, 171 ?), and H?? from Culgoora Solar Observatory at Narrabri, Australia, we present a unique observational signature of a propagating supersonic plasma blob before an M6.2-class solar flare in active region 10808 on 9 September 2005. The blob was observed between 05:27 UT and 05:32 UT with almost a constant shape for the first 2??C?3 min, and thereafter it quickly vanished in the corona. The observed lower-bound speed of the blob is estimated as ???215?km?s^?1 in its dynamical phase. The evidence of the blob with almost similar shape and velocity concurrent in H?? and TRACE 171 ? images supports its formation by a multi-temperature plasma. The energy release by a recurrent three-dimensional reconnection process via the separator dome below the magnetic null point, between the emerging flux and pre-existing field lines in the lower solar atmosphere, is found to be the driver of a radial velocity pulse outwards that accelerates this plasma blob in the solar atmosphere. In support of identification of the possible driver of the observed eruption, we solve the two-dimensional ideal magnetohydrodynamic equations numerically to simulate the observed supersonic plasma blob. The numerical modelling closely match the observed velocity, evolution of multi-temperature plasma, and quick vanishing of the blob found in the observations. Under typical coronal conditions, such blobs may also carry an energy flux of 7.0×10⁶?erg?cm^?2?s^?1 to balance the coronal losses above active regions.     

2D cooperative inversion of direct current resistivity and gravity data: A case study of uranium bearing target rock

Interpretation of a single geophysical data set is not sufficient to get complete subsurface information. Cooperative or joint inversion of geophysical data sets is the preferred method for most case studies. In the present study, we present the results of the cooperative inversion approach of direct current resistivity and gravity data. The algorithm uses fuzzy c-means clustering to determine the petrophysical relationship between density and resistivity to obtain the similarity. Synthetic data set has demonstrated that the cooperative inversion approach can produce more reliable and better resistivity and density models of the subsurface as compared to those obtained through individual inversions. To utilize the presented cooperative inversion algorithm, the number of geologic units (number of clusters) in the study region must be known a priori. As a field study, the cooperative inversion approach was used to identify the extension of uranium-bearing target rock around the Beldih open cast mine. We noted the inconsistencies in both resistivity and density models obtained from the individual inversions. However, the presented cooperative inversion approach was able to produce similar resistivity and density models while maintaining the same error level of the respective individual inversions. We have considered four geologic units in the presented cooperative inversion as a field case study. We have also compared our cooperative results with drilled borehole and found to be a reliable tool to differentiate between the target rocks (kaolinite and quartz–magnetite–apatite rocks) and the ultramafic rock (host rock quartzite/alkaline granite). However, this study is subject to certain limitations such as the inability to differentiate between closely spaced kaolinite and quartz–magnetite–apatite rocks.     

Geospatial Modelling and Mapping of Snow Avalanche Susceptibility

The main objective of this study was to mapping the potential avalanche susceptible zones in Siachen region of the Western Indian Himalaya. A geospatial analytical hierarchy process (AHP) model based on expert judgements has been applied in this study. Five most important terrain based avalanche occurrence parameters including slope, aspect, curvature, elevation and ground cover are employed in the present model. The ASTER GDEM and Landsat 8 OLI imagery are used to generate the avalanche occurrence parameters. A pairwise comparison matrix is computed to estimate the weight values for input terrain parameters. These weight values are then assigned to each respective avalanche occurrence parameter and employed in a geospatial AHP model to generate an avalanche susceptibility map. Finally, an avalanche inventory has been utilized to validate the results. The avalanche susceptibility map has been compared with the avalanche inventory map by calculating the area under the receiver operating characteristics curve (ROC-AUC) technique.     

Multi isotopic approach to study temporal variation of groundwater quality in coastal aquifer of Saijo plain, Shikoku Island, Japan

In order to delineate geochemical processes and its relation with groundwater quality evolution, hydrochemical and isotopic analysis were carried out in coastal groundwater of Saijo plain, western Japan. From analytical results, even within a small distance from the coast; ionic concentration of water samples varies a lot which infers non-homogenous and patchy distribution of different aquifer system (complex geology). From stable isotopic results, it was found that most of sample points plotted near the local meteoric water line (LMWL) i.e. origin of ground water is meteoric in principle; however point away from the LMWL might favors exchange with rock minerals.     

GIS application to determine the effect of topography on landuse in Ashwani Khad watershed

The landuse status of Ashwani Khad watershed has been obtained using 1RS-ID satellite data for 1999 and further topographic analysis has been carried out using GIS software-ARC/ INFO and ARCVIEW. It has been found that of the total geographical area (85.30 sq. km) of the Ashwani Khad watershed which lies between 30°50′ to 31°N latitude and 77°05′ to 77° 15′E longitude in Himachal Pradesh, 54.53 % constituted wasteland, 33.55% agriculture and least 11.92 % forest. The altitude, aspect and slope have exhibited marked effect on land utilization. Agriculture and wasteland have been found maximum in mid altitude (1300-1500 m) and moderate slopes (13.2-26.4 degree), whereas, agriculture and forest have been maximum in flat and north aspect.     

GIS-based morphometric analysis of five major sub-watersheds of Song River,Dehradun District,Uttarakhand with special reference to landslide incidences

Evaluation of the morphometric parameters requires preparation of drainage map, contour map, ordering of the various streams and measurements of catchment area, perimeter, relative relief, relief ratio, length of drainage channels, drainage density, drainage frequency, bifurcation ratio, texture ratio, circulatory ratio and constant channel maintenance, which help to understand the nature of the drainage basin. The present study involves the Geographic Information System (GIS) analysis techniques to evaluate and compare linear, relief and aerial morphometry of the five subwatersheds of Song River (tributary of the Ganga River) with special reference to landslide incidences, for future development and planning of the watershed. Jakhan Rao, Song River, Bandal Nadi, Baldi Nadi and Suswa Nadi are the five major subwatersheds of the Song River basin. All the subwatersheds are basically of 5^th to 6^th order. Drainage patterns are mainly dendritic to sub dendritic. The drainage pattern of the Song River basin is mainly structurally controlled and the area is characterized by high to moderate relief. The asymmetric factor indicates that the tectonic rotation of the four subwatersheds is upward on the right side of the drainage basin and only one sub-watershed is downward. The numbers of the landslide incidences are also more in the upward side, than the downward side of the Song River basin.     

Delineation of ground water potential zones in a hard Rock Terrain of Bargarh District, Orissa using IRS data

In the present paper, various groundwater potential zones for the assessment of groundwater availability in a hard rock terrain have been delineated with the help of hydrogeological parameters using satellite IRS- 1B-LISS-II digital data. Area selected for this study is a part of Bargarh district, Orissa, India covering an area of about 680 square km. Satellite data has been used to prepare geological-cum-lineaments, geomorphological, landuse and drainage maps. The various thematic maps have been integrated with the help of Geographic Information System to demarcate the poor to excellent groundwater potential zones. Weightage has been given to various groundwater controlling factors to the total groundwater potential in each segment of study area. Subsequently, several sites were selected and pumping tests carded out in the area. The results show that among others, lineaments as well as drainage density are the most important contributory factors in the groundwater potential of various geomorphic units in the area of investigation.