Abstract:
Groundwater is a vital resource to support food and freshwater security in India. Changes in climate and anthropogenic activities affect groundwater storage. Here, we examine the role of precipitation and policy changes on groundwater storage in western India (WI) using observed well data from Central Groundwater Board (CGWB) and satellite data from Gravity Recovery and Climate Experiment (GRACE) to understand the linkage between climate and groundwater variability from 1996 to 2016 and 2002 to 2016, respectively. We find that terrestrial water storage (TWS) and groundwater storage from GRACE have declined (with a rate of ??3.67 km3/year) in WI during 2002-2016. Analysis of groundwater storage change in two states (Gujarat and Rajasthan) of WI reveals contrasting patterns associated with observation wells and GRACE groundwater storage. Precipitation has increased in WI during 1996-2016, which is strongly coupled with the variability of groundwater storage associated with observation wells which are mostly available at shallow levels. However, groundwater storage, as revealed by the GRACE data, is prominently linked with groundwater pumping and policies related to reducing the amount of groundwater abstraction for irrigation. Rejuvenation of groundwater storage in Gujarat can be attributed to less number of deep tube wells as well as to the policy measures (e.g., electricity supply for irrigation) taken to reduce groundwater pumping for irrigation. On the other hand, groundwater depletion in Rajasthan is primarily due to groundwater pumping for irrigation. Our results highlight the need for managing groundwater resources in semi-arid western India.