Impacts of climate change on terrestrial hydrological components and crop water use in the Chesapeake Bay watershed

Summary/Abstract

This study assessed the impacts of climate change on terrestrial hydrological components and Crop Water Use (CW_U) over the Chesapeake Bay watershed using a combination of Global Climate Models (GCMs) and a land surface model. To better understand the impacts of climate change on the hydrological cycle, long-term simulations of multiple earth system models from the Coupled Model Intercomparison Project (CMIP Phase 5) are statistically downscaled and bias-corrected using Multivariate Adaptive Constructed Analogs (MACA) scheme for use as model forcing. Precipitation indices from the twenty MACA-based GCMs are used to identify six best performing models. A mesoscale approach is developed, where CW_U is estimated by accounting for the impacts of changing climate conditions and rising CO₂ levels. Daily grid-based crop coefficients are derived from evapotranspiration data. The findings indicate a significant annual increase in precipitation (10 %) and temperature (+4.5 K) for the RCP 8.5 scenario towards the end of the 21^st century. A significant reduction (13 % and 17 % respectively) in CW_U is estimated for corn and soybeans, resulting from increased total precipitation and rising CO₂ levels suppressing evapotranspiration. Our results indicate that even in a warmer regime, crop water use decreased due to rising CO₂ concentrations due to climate change.