ISOTOPIC CHARACTERIZATION OF GROUNDWATER IN LOWER PART OF SUTLEJ BASIN

Abstract

The study area extends between 30.8°-3 1 .8°N to 750-76.80E and is essentially the Bist doab region of the lower Suticj basin. It is located in the states of Punjab and Himachal Pradesh. A sampling survey lasting five days was conducted during the post monsoon season from the 4th of November to the 8th of November 2013. Parameters such as Temperature, BC of the sample and the depth from which groundwater is sampled are recorded while sampling along with the physical parameters such as latitude, longitude and elevation of the sample site. The samples were processed in LGR's Liquid Water Isotope Analyser at the National Institute of Hydrology, Roorkee for obtaining the values of 6180 and 6D. The resultant data is plotted following kriging extrapolation technique using Surfer software to generate contours to illustrate the spatial variation of the isotopic parameters. The dataset is divided into two parts based on the depth from which the groundwater is collected. The groundwater from depths less than 80m (-250ft) was considered as shallow groundwater and the groundwater from depths greater than 80m was considered to be from deeper origins. Various plots between 8180, öD, EC and Temperature were drawn to understand the characterization of the isotopes in shallow and deep groundwater. The relationship between 6180 and 3D for shallow groundwater in Bist doab region during the post monsoon season of the year 2013 is öD = 6.246'80 - 4.21 and for deeper groundwater is 6D = 6.82 80 + 0.43. The average values of d-excess, 5180, 6D for shallow groundwater are 9.1, -7.5, and -51.2 respectively while for deeper groundwater the average values are 10.2, -8.3, and -56.3 respectively. Precipitation and irrigation baekflow cause recharge of groundwater in majority of the study area while river and canal systems cause significant recharge only in handful regions in the study area during the post monsoon season