Evaluating the impact of projected CO2, temperature, and rainfall change on groundwater resources in a rice–wheat dominated cropping region of northwestern India

Abstract

Increasing CO2 concentration, temperature rise, and changes in rainfall due to climate change are expected to influence groundwater resources in irrigated agricultural regions. A simulation study using AquaCrop and MODFLOW models was undertaken to assess the combined effects of increasing CO2 concentrations, temperature, and rainfall changes on groundwater behavior in a rice–wheat cropping region of northwest India. Simulations were carried out for the 2016–2099 period under two scenarios: increasing CO2 concentrations corresponding to different RCPs (Scenario-I) and at a constant CO2 concentration of 369.4 ppm (Scenario-II). The results indicate that elevated CO2 negates the effect of rising temperature on evapotranspiration (ET) and water demand, and thus, lower ET is simulated under Scenario-I than Scenario-II for different RCPs during the future periods. The lower projected ET resulted in lower rice (2.3%–6.3%) and wheat (1.4%–16.1%) irrigation demand under Scenario-I than under Scenario-II. Of all RCPs, the lowest groundwater level (GWL) decline of 9.2, 20.5, and 24.4 m from the reference GWL (18.85 m) at the end of the early, mid-, and end-century periods, respectively, is projected under RCP8.5 and Scenario-I. Simulation results indicate that CO2 concentration plays an important role while assessing climate change effects on groundwater in irrigated agricultural systems. HIGHLIGHTS Quantified crop water budgeting components and their effect on groundwater levels in response to elevated CO2 concentration.; Rice irrigation requirement (IR) would decrease slightly while wheat IR significantly increased in future periods both in elevated CO2 and constant CO2 concentration scenarios.; Groundwater level is projected to decline less in elevated CO2 than in constant CO2 concentration scenario.;

Keywords

• aquacrop
• climate change
• co2 concentration
• crop evapotranspiration
• groundwater level
• irrigation requirement