Long-term groundwater recharge rates across India by in situ measurements

Soumendra N Bhanja,Bridget R Scanlon,Shubha Verma,R Rangarajan,Abhijit Mukherjee,Pragnaditya Malakar

doi:10.5194/hess-23-711-2019

Abstract

Abstract. Groundwater recharge sustains groundwater discharge, including natural discharge through springs and the base flow to surface water as well as anthropogenic discharge through pumping wells. Here, for the first time, we compute long-term (1996–2015) groundwater recharge rates using data retrieved from several groundwater-level monitoring locations across India (3.3 million km2 area), the most groundwater-stressed region globally. Spatial variations in groundwater recharge rates (basin-wide mean: 17 to 960 mm yr−1) were estimated in the 22 major river basins across India. The extensive plains of the Indus–Ganges–Brahmaputra (IGB) river basins are subjected to prevalence of comparatively higher recharge. This is mainly attributed to occurrence of coarse sediments, higher rainfall, and intensive irrigation-linked groundwater-abstraction inducing recharge by increasing available groundwater storage and return flows. Lower recharge rates (<200 mm yr−1) in most of the central and southern study areas occur in cratonic, crystalline fractured aquifers. Estimated recharge rates have been compared favorably with field-scale recharge estimates (n=52) based on tracer (tritium) injection tests. Results show that precipitation rates do not significantly influence groundwater recharge in most of the river basins across India, indicating human influence in prevailing recharge rates. The spatial variability in recharge rates could provide critical input for policymakers to develop more sustainable groundwater management in India.

Highlights

India represents ∼ 18 % of the global population but occupies < 3 % of the global land area (Food and Agriculture Organization of the United Nations, 2013)
High recharge rates in 2010 are attributed to increased space for recharge related to lower precipitation in 2009 (Fig. 2), with 22 out of 26 meteorological subdivisions declared as rainfall deficit in India (National Climate Centre, 2013)
Differential spatial patterns of climate, geology and withdrawal linked to irrigation are the major reasons for spatial heterogeneity in groundwater recharge in India

Summary

Introduction

India represents ∼ 18 % of the global population but occupies < 3 % of the global land area (Food and Agriculture Organization of the United Nations, 2013). Agricultural activity is intensive, and parts of India support the highest rate of irrigated arable land globally (Siebert et al, 2013). Few studies have reported groundwater recharge at a limited number of locations (Goel et al, 1975; Bhandari et al, 1982; Athavale et al, 1992, 1998; Rangarajan et al, 1995, 1997, 1998; Rangarajan and Athavale, 2000; Scanlon et al, 2010; Fig. 1). Bhanja et al.: Long-term groundwater recharge rates across India by in situ measurements drawal, more than 50 % is attributed to groundwater in India (Central Ground Water Board, 2011)

Objectives

Results

Conclusion