Modeling climate change impact on groundwater and adaptation strategies for its sustainable management in the Karnal district of Northwest India

Extensive use of groundwater in the rice–wheat cropping system of northwest India has resulted in groundwater depletion at an alarming rate of 33–88 cm per year over the past 2–3 decades. Projected climate change is likely to affect crop water demand, groundwater withdrawal, and replenishment in future. A modeling study was undertaken to simulate the impact of climate change on groundwater resources under existing rice–wheat cropping system and with revised crop management strategies in the Karnal district of Northwest India. Different cop management strategies considered are marginal shift in sowing dates of rice and wheat, and fractional diversification of rice area to maize. MODFLOW software driven by the projected climate change scenarios under four representative concentration pathways (RCP2.6, RCP4.5, RCP6.0, and RCP8.5) were used for simulating groundwater behavior in the study area under business as usual and proposed crop management strategies. Simulation results indicated 4.3–61.5 m (28.9–291.2%) additional decline in groundwater levels in different zones of the study area under different RCPs by the end century (2070–2099) period in relation to the reference groundwater level of year 2015 under the existing sowing dates of 15 June for rice and 15 November for wheat. Maintaining rice sowing date at 15 June but advancing wheat sowing date by 10 days can reduce groundwater decline by 9.8–14.4%, 14.4–19.6%, and 18.1–25.8% under different RCPs by the end of early (2010–2039), mid (2040–2069), and end (2070–2099) century periods, respectively, vis-à-vis prevailing sowing dates. Replacing 20%, 30%, and 40% rice area with maize in rice–wheat system is likely to reduce groundwater decline by 7.1 (24.9%), 10.1 (35.3%), and 13.8 m (48.5%), respectively, in comparison to projected end century (2099) decline of 28.5 m under the prevailing sowing dates of rice–wheat. However, declining groundwater trend of rice–wheat would be reversed with the replacement of 80% rice area under maize crop. Simulation results suggest that specific crop management strategies can potentially moderate groundwater decline in the study area under the envisaged climate change.