Groundwater Recharge in Natural Dune Systems and Agricultural Ecosystems in the Thar Desert Region, Rajasthan, India

Authors

Bridget Scanlon, University of Texas at AustinFollow
Abhijit Mukherjee, Alberta Geological Survey
John B. Gates, University of Nebraska-LincolnFollow
Robert C. Reedy, University of Texas at AustinFollow
Amarendra K. Sinha, University of Rajasthan

Document Type

Article

Date of this Version

2010

Comments

Published in Hydrogeology Journal (2010) 18: 959-972. Copyright 2010, Springer-Verlag. Used by permission.

Abstract

Water and nutrient availability for crop production are critical issues in (semi)arid regions. Unsaturated-zone Cl tracer data and nutrient (NO₃ and PO₄) concentrations were used to quantify recharge rates using the Cl mass balance approach and nutrient availability in the Thar Desert, Rajasthan, India. Soil cores were collected in dune/interdune settings in the arid Thar Desert (near Jaisalmer) and in rain-fed (nonirrigated) and irrigated cropland in the semiarid desert margin (near Jaipur). Recharge rates were also simulated using unsaturated zone modeling. Recharge rates in sparsely vegetated dune/interdune settings in the Jaisalmer study area are 2.7-5.6 mm/year (2-3% of precipitation, 165 mm/year). In contrast, recharge rates in rain-fed agriculture in the Jaipur study area are 61-94 mm/year (10-16% of precipitation, 600 mm/year). Minimum recharge rates under current freshwater irrigated sites are 50-120 mm/year (8-20% of precipitation). Nitrate concentrations are low at most sites. Similarity in recharge rates based on SO₄ with those based on Cl is attributed to a meteoric origin of SO₄ and generally conservative chemical behavior in these sandy soils. Modeling results increased confidence in tracer-based recharge estimates. Recharge rates under rain-fed agriculture indicate that irrigation of 20-40% of cultivated land with 300 mm/year should be sustainable.