Praveen K. Thakur

Assessment of the effectiveness of DRASTIC in predicting the vulnerability of groundwater to contamination: a case study from Fatehgarh Sahib district in Punjab, India

The quality of groundwater has been declining in the Fatehgarh Sahib district of Punjab, India, over the last decade due to the enormous increase in the number of tube wells for the agricultural activities. The vulnerability of groundwater to contamination in the district was assessed using the DRASTIC model. Validation of vulnerable zones was undertaken using the chemical analysis of groundwater samples from the district. Based on this investigation, the inherent problems associated with the DRASTIC model are discussed as potential measures to improve the assessment of groundwater vulnerability.

Assessment of the effect of slope on runoff potential of a watershed using NRCS-CN method

The rainfall-runoff is a very complex hydrological phenomenon, as this process is highly non-linear, time-varying and spatially distributed. The average slope within the watershed together with the overall length and retardance of overland flow are considered to be the main factors which govern the runoff process. The natural resources conservation service curve number (NRCS-CN), formerly known as soil conservation services curve number, is the most widely used method to estimate direct runoff from rainfall, due to its simplicity and the use of the single CN parameter. However, the NRCS-CN method has been developed for limited watershed area and slope. In the present study, the modified NRCS-CN method for slope and CN conversion have been investigated to determine runoff potential of a watershed in geo-spatial environment. Solani watershed, which is a sub-watershed of Ganga basin located partly in Uttarakhand and Uttar Pradesh states of India; has been considered for analysis. The daily rainfall-runoff study has been carried out for year 2006. It was found that slope factor effects runoff estimation significantly.

Snow physical parameters estimation using space-based Synthetic Aperture Radar

This study has been done using Polarimetric Synthetic Aperture Radar (SAR) data to estimate the snow physical properties (snow wetness and snow density), inManali sub-basin of Himachal Pradesh, India. The SAR data used are of Radarsat-2 (RS2) and Environmental Satellite, Advanced Synthetic Aperture Radar (ASAR). SAR-based inversion models were implemented in Mathematica and MATLAB, and have been used for finding out wet and dry snow dielectric constant, snow wetness and snow density. The SAR-based inversion models were implemented separately for fully polarimetric RS2 and dual polarimetric ASAR Alternate Polarization System datasets. Masks for forest, built area, layover and shadow were considered in estimating snow parameters. The overall accuracy in terms of R 2 value comes out to be 0.86 for snow wetness and 0.84–0.72 for snow density based on the ground truth data for subset area of Manali sub-basin of Beas river up to Manali.

Groundwater: a regional resource and a regional governance

Groundwater is a valuable renewable resource for human life. The two major threatening issues being faced by groundwater are its depletion and degradation which affect both the quantity and the quality of groundwater. Though scientific output has progressed well ahead in the domain of groundwater, very little has been done with respect to the establishment of the groundwater governance framework. Groundwater is perceived as a widely distributed resource, but it is fundamentally a local entity. The paper presents the groundwater governance framework from the regional perspective of Fatehgarh Sahib district of Punjab, India—an over-exploited groundwater region.

QUANTITATIVE ASSESSMENT OF SUSTAINABILITY OF PROPOSED WATERSHED DEVELOPMENT PLANS FOR KHAROD WATERSHED, WESTERN INDIA

Sustainability of watershed development plan is assessed through the quantification of thethree major sub-components of Water Balance, namelySurface Runoff (SR), Ground Water Recharge (GWR) andEvapotranspiration (ET) for 71 micro-watersheds of Kharod watershed (1100 km2 area) located in Western India. Annual estimates at micro-watershed level are carried out for two scenarios: A) The current water resources and land use/land cover scenario and B) Envisaged changed water resources and land use/land cover scenario after implementing all prescriptions for micro-watershed development. Finally water balance components level analysis and comparison was done to see the impact and assess the sustainability of envisaged watershed development scenario. It is estimated that there is a decrease of 40.2 mm in surface runoff component, increase of approx. 4 mm in groundwater recharge, increase of 102.3 mm in actual evapotranspiration for post-developmental scenario on annual basis. The computation of actual evapotranspiration (ETa) showed that there is net increase in the ETa after the post-development scenario. Also the surface water storage has increased from 21.2 mm to 65.3 mm. Overall there is 164.9 mm of available water balance after implementation of developmental activities which reflects the sustainability of the proposed development plans.

Multi-criteria evaluation of hydro-geological and anthropogenic parameters for the groundwater vulnerability assessment

Groundwater contamination assessment is a challenging task due to inherent complex dynamisms associated with the groundwater. DRASTIC is a very widely used rapid regional tool for the assessment of vulnerability of groundwater to contamination. DRASTIC has many lacunas in the form of subjectivities associated with weights and ratings of its hydro-geological parameters, and, therefore, the accuracy of the DRASTIC-based vulnerability map is questioned. The present study demonstrates the optimisation of the DRASTIC parameters along with a scientific consideration to the anthropogenic factors causing groundwater contamination. The resulting scientific consistent weights and ratings to DRASTIC parameters assist in the development of a very precise groundwater vulnerability map highlighting different zones of different gravity of contamination. One of the most important aspects of this study is that we have considered the impact of vadose zone in a very comprehensive manner by considering every sub-surface layer from the earth surface to the occurrence of groundwater. The study area for our experiment is Fatehgarh Sahib district of Punjab which is facing several groundwater issues.

Ice sheet features identification, glacier velocity estimation and glacier zones classification using high resolution optical and SAR data

Ice sheet features, glacier velocity estimation and glacier zones or facies classification are important research activities highlighting the dynamics of ice sheets and glaciers in Polar Regions and in inland glaciers. The Cband inSAR data is of ERS 1/2 tandem pairs with one day interval for spring of 1996 and L-band PolinSAR data of ALOS-PALSAR-2 for spring of 2015 is used in glacier velocity estimation. Glacier classification is done using multi-temporal C-and L-band SAR data and also with single date full polarization and hybrid polarization data. In first part, a mean displacement of 9 cm day-1 was recorded using SAR interferometric technique using ERS 1/2 tandem data of 25-26 March 1996. Previous studies using optical data based methods has shown that Gangotri glacier moves with an average displacement of 4 cm and 6 cm day-1. As present results using ERS 1/2 data were obtained for one day interval, i.e., 25th March 05:00pm to 26th March 05:00 pm, 1996, variation in displacement may be due to presence of snow or wet snow melting over the glacier, since during this time snow melt season is in progress in Gangotri glacier area. Similarly the results of glacier velocity derived using ALOSPALSAR- 2 during 22 March – 19 April 2015 shows the mean velocity of 5.4 to 7.4 cm day-1 during 28 day time interval for full glacier and main trunk glacier respectively. This L-band data is already corrected for Faraday’s rotation effects by JAXA, and tropospheric correction are also being applied to refine the results. These results are significant as it is after gap of 20 years that DInSAR methods has given glacier velocity for fast moving Himalayan glacier. RISAT-1 FRS-1 hybrid data is used to create Raney’s decompositions parameters, which are further used for glacier zones classification using support vector machine based classification method. The Radarsat-2 and ALOS-PALSAR-2 fully polarized data of year 2010 and 2015 are also used for glacier classification. The identified and classified glaciers zones in Gangotri area are debris covered ice, clean ice, percolation zone, wet snow zone, ice wall, supra-glacier lakes and moraines, similarly ice sheet features and glacier landforms such as such as nunataks, wind scoop, glacier flow paths, moraine, horn, sastrugi, and crevasses were identified in Antarctic. RISAT-1 FRS-1 data was also successful in mapping the Crevasses hidden under wind-blown ice in Antarctic’s study area.

Hypothetical scenario–based impact assessment of climate change on runoff potential of a basin

Climate change and its impact on hydrological processes are causes for widespread concern and challenge. In this regard, large numbers of global and regional circulation models (GCMs and RCMs) have been developed to study the future climate. However, these GCMs and RCMs have large uncertainties in defining climate scenarios. The uncertainties associated with these models provided an opportunity to investigate the impact of climate change on the runoff potential of a major basin in India under different assumed plausible hypothetical scenarios. These scenarios were developed by increasing the temperature by 1°C, 2°C and 3°C and rainfall by 5%, 10% and 15%, and then combinations of both. Understanding the hydrologic response of very large river basins again poses a huge challenge to hydrologists. Therefore, an attempt has been made to exploit the capabilities of a variable-infiltration-capacity macro-scale hydrological model to simulate the Satluj river basin. It was found that a slight change in climate may cause huge differences in the hydrological regime of the basin.

Suitability Analysis of Groundwater Quality for Domestic and Irrigation Usage in Yamuna Nagar District, India: A GIS Approach

The main source to fulfill the enormous needs of water both for domestic and agricultural purposes in the densely cultivated region of Yamuna Nagar district of Haryana (India) is the water under earth. Since enough quantity of good quality water has been readily available, the water quality concerns are often neglected. In the present study analysis of the geochemical characteristics of groundwater to assess its suitability for domestic and irrigation purposes has been done. Fifty-five samples were collected in the months of June (pre-monsoon) and October (post-monsoon) from the bore wells. These samples were analysed for various parameters and were compared with various national and international standards to determine the suitability of water for domestic and irrigation use. The thematic maps for hydrogen ion concentration (pH), total dissolved solids (TDS), total hardness (TH), electric conductivity (EC), sodium adsorption ratio (SAR), percent sodium (Na%) and residual sodium carbonate (RSC) were prepared in GIS environment. These maps were further classified as per given standards to study the spatial variations of quality parameters and their suitability for drinking and irrigation purposes. Investigations revealed that groundwater in general was hard for domestic use. However it was within the safe limits for drinking. Furthermore groundwater quality was well within the desirable to permissible limits for irrigation purpose.

Impact of LULC change on the runoff, base flow and evapotranspiration dynamics in eastern Indian river basins during 1985–2005 using variable infiltration capacity approach

As a catchment phenomenon, land use and land cover change (LULCC) has a great role in influencing the hydrological cycle. In this study, decadal LULC maps of 1985, 1995, 2005 and predicted-2025 of the Subarnarekha, Brahmani, Baitarani, Mahanadi and Nagavali River basins of eastern India were analyzed in the framework of the variable infiltration capacity (VIC) macro scale hydrologic model to estimate their relative consequences. The model simulation showed a decrease in ET with 0.0276% during 1985–1995, but a slight increase with 0.0097% during 1995–2005. Conversely, runoff and base flow showed an overall increasing trend with 0.0319 and 0.0041% respectively during 1985–1995. In response to the predicted LULC in 2025, the VIC model simulation estimated reduction of ET with 0.0851% with an increase of runoff by 0.051%. Among the vegetation parameters, leaf area index (LAI) emerged as the most sensitive one to alter the simulated water balance. LULC alterations via deforestation, urbanization, cropland expansions led to reduced canopy cover for interception and transpiration that in turn contributed to overall decrease in ET and increase in runoff and base flow. This study reiterates changes in the hydrology due to LULCC, thereby providing useful inputs for integrated water resources management in the principle of sustained ecology.