Understanding Stable Isotope Systematics of Salinity Affected
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J. Earth Syst. Sci. (2020) 129:109 Ó Indian Academy of Sciences https://doi.org/10.1007/s12040-020-1380-6 (0123456789().,-volV)(0123456789().,-volV) Understanding stable isotope systematics of salinity aAected groundwater in Mewat, Haryana, India 1, 1 1 2 GOPAL KRISHAN *, N C GHOSH ,CPKUMAR ,LALIT MOHAN SHARMA , 3 3 1 1 BRIJESH YADAV ,MLKANSAL ,SURJEET SINGH ,SKVERMA and 1 GOKUL PRASAD 1National Institute of Hydrology, Roorkee, Uttarakhand 247 667, India. 2Sehgal Foundation, Gurugram, Haryana 122 003, India. 3Indian Institute of Technology, Roorkee, Uttarakhand 247 667, India. *Corresponding author. e-mail: [email protected] MS received 29 August 2018; revised 15 November 2019; accepted 29 January 2020 Mewat district in Haryana located in the semi-arid region of India has been reported continual increase of groundwater salinity. Stable isotopes, d18O and dD, of groundwater and rain water were successfully used for characterization and source identiBcation of salinity aAected groundwater in the area. Eleven rep- resentative groundwater samples were of the pre-monsoon (May), monsoon (August) and post-monsoon (November) seasons were analyzed for determining EC, d18O, dD and other parameters. The mean EC of the samples was determined 6712 lS/cm for the pre-monsoon, 4743 lS/cm for the monsoon and 6602 lS/ cm for the post-monsoon. The slope of LMWL (8.13) obtained from the bivariate plot showed a very close to the GMWL (8) and the slope of rain water (7.47) and groundwater samples found lied on the right of the LMWL for all the seasons. Slopes observed for the pre-monsoon (6.76), monsoon (5.63) and post- monsoon (6.11) seasons indicated some evaporative enrichment of water before the groundwater recharge. The increase of d-excess values from 0.74 in pre-monsoon to 3.75 in monsoon and 4.46 in post-monsoon seasons suggested modern recharge with low evaporation. The recharge by meteoric water was noted from the decrease in the mean value of EC in the monsoon season and its increase in the post-monsoon season, which suggested possible ‘mechanism of mixing’. All these processes qualitatively predicted the recharge and discharge locations in the study area. Keywords. Groundwater; salinity; stable isotopes; source identiBcation; Mewat, Haryana. 1. Introduction The Mewat area in Haryana state (India) that characterizes a semi-arid region with annual rain- Isotopes are increasingly being applied in hydro- fall ranges between 200 and 500 mm (Singh et al. geological investigations as a complementary tool 2007) describing seasonal lakes and moderate for assessment of aquifer Cow and water quality groundwater in alluvial aquifers (Krishan et al. characteristics. Stable isotopes data have shown 2017), faces the problem of intrinsic widely spread excellent results in identiBcation of source water groundwater salinity problem. Groundwater is the and demonstrating the dynamics of groundwater in major source of water both domestic and agricul- an aquifer system (Stute et al. 1992; Ekwurzel et al. ture, but 84% of the total 503 villages covering 1994). an area of about 1266 km2 has unusable saline 109 Page 2 of 9 J. Earth Syst. Sci. (2020) 129:109 groundwater; remaining 16% of the villages, (ii) anthropogenic driven processes (Gampson et al. covering 241 km2 has fresh groundwater, which are 2015). mostly located along the foothills of the Aravalli The present study deals with characterization range. This fresh groundwater resource is vulner- and source identiBcation of salinity aAected able for use in domestic, irrigation and industrial groundwater in Mewat, Haryana using stable iso- purposes (CGWB 2012; Krishan et al. 2017) due to topes (d18O, dD) of groundwater and rain water being overused and abused by the local water together with identiBcation of saline zones and maBa. One third households in the region have Bnding the groundwater recharge zones. their own bore wells and most of the prosperous farmers have started consolidating their lands in the freshwater zones near the ridges and foothills of 2. Study area the Aravalli range (Priyanka et al. 2018). Pressure on the freshwater resource increases sturdily with Haryana state in India lies mainly in the Indo- an abstraction of 605 m3/day during the summer Gangetic Plains and River Yamuna, a tributary of time, when the natural supply decreases consider- Ganga Cows in the eastern boundary of the state. ably. This phenomenon has led groundwater There is a depressional region in the state facing depletion in the fresh water zone (high abstraction, drainage problem and resulting in water logging i.e., 605 m3/day and less recharge rate, i.e., 32.5 and salinity (Kulkarni et al. 1989). mm/year) together with spread of intrinsic saline The salinity of groundwater in Haryana has been water zone. Areas having fresh water have steep explained by different processes (Krishan 2019) as: slopes with high rainfall intensities, less inBltra- dissolution of evaporite deposits; concentration of tion. Run oA generated through rains from these salts due/evapotranspiration, especially in water- slopes recharges groundwater in the foothill region logged areas. of Aravalli hills, but it becomes unusable entering Mewat (Nuh) district in Haryana covering an saline zones (Thomas et al. 2012). During low area of 1507 km2 lies between 27°300–28°200N lati- rainfall periods, farmers are forced to use the saline tude and 76°540–77°200E longitude (Bgure 1). Its groundwater for irrigation, domestic and other Bve blocks namely, Tauru, Nuh, Nagina, Firozpur purposes, which in turn aAect soil health as well as Jhirka and Punhana are surrounded by Gurgaon the crop yields (Mehra 2016). on the North, Rewari district to the West, Farid- These essentially necessitated an in-depth study abad district to the East and Rajasthan to the for critical understanding of issues which include, South. Mewat is one of the most backward districts identiBcation of salinity aAected pockets and their of Haryana with population of 10,89,263 (Census source and, origin, Cow paths of groundwater 2011). It consists of alluvial plain in the central identiBcation for suggesting proper treatment and part formed by river deposits that developed allu- management of water resources in the area. The vial fans, a Cood plain and is crossed by the area being remotely located, information/data degraded Aravalli ranges at southwest and few required for such analyses are difBcult to acquire locations at southeast. Topographically, the study using conventional hydro-geological methods. area starts from the Aravalli range from the block Stable isotope (18O, D) systematics tool as con- Tauru (*280 msl), which is covered by shrubs and servative, environmental tracers (Krishan 2015) irrigated lands in the valley. There is no general can provide direct insights for understanding slope rather some altitudinal differences observed. movement, distribution of groundwater, its qual- Some topographic depressions give rise to natural ity, recharge and contamination (Parizi and lakes in this area. The annual mean maximum Samani 2014; Hassen et al. 2016) by comparing temperature is about 40°C and annual mean min- variations in d18O and dD ratios with respect to the imum is 5.1°C. The temperature decreases from the world and local precipitation data: i.e., the global high elevated areas to low elevation areas. The meteoric water line (GMWL) and the local mete- annual precipitation is about 594 mm spread in 31 oric water line (LMWL), respectively. The isotope days (Singh et al. 2007; CGWB 2012) and 75% ratios of water varies with the season (Wu et al. of which occurs during June–September; Octo- 2014) and groundwater isotope values differ from ber–December period constitutes post-monsoon GMWL and LMWL due to the (i) natural inter- season; January to the beginning of March is the mittent processes such as evaporation, inBltration, winter season and mid-March to May is the pre- and percolation (Blasch and Bryson 2007) and monsoon season. Based on the rainfall and weather, J. Earth Syst. Sci. (2020) 129:109 Page 3 of 9 109 Figure 1. Study area showing sampling locations. the district has been categorized as the semi-arid zone. Aquifers in the district are largely made up of alluvium of quaternary age and sand, clay and kankar constitute the deeper layers of the parent material (Arya et al. 1999). The Quaternary allu- vium, with thickness 3000 m in the northeastern part and 1000 m in the southwest, has been deposited by the present and ancestral river sys- tems commenced during mid-Tertiary time in the subsiding trough (foredeep) adjacent to rising Himalayan Ranges (Kulkarni et al. 1989). There are thick deposits of clay at a depth of 50–150 m below Figure 2. Lithology of the study area. the ground surface, but lenticular clay horizons at shallow depths. There is a greater thickness of the lithologs of the borelogs are shown in Bgure 2. The sand and gravel sediments in northern part of the lithologs of the borelogs mainly showed properties state having fresh water and the southern part of of a good aquifer, except the clay and silt layer the area with predominance of clay and less thick- formations. From Bgure 2, it was observed that the ness of sand horizons have saline waters. formations having properties of good aquifer are Making use of ‘Rockworks’ software – a com- intermittent in nature, i.e., there is multiple aqui- prehensive software program for creating 2D and fer formations at a particular depth. However, clay 3D maps, logs and cross sections, geological mod- and silty clay proBle have continuous areal extent els, general geology diagrams, etc., the borelogs at different layers. Sand and Sand Kankar, which data were analyzed for delineation of the litholog- are good aquifer materials, have intermittent areal ical proBles and aquifer characterization. The point extent at different depths.