DRAINMOD predicted impact of climate change on hydrology, corn yield, and drainage design in the Western Lake Erie Basin, United States

Climate change presents challenges to agricultural water management, necessitating a reevaluation of subsurface drainage design for sustainable crop production. The objectives were to (1) investigate the impacts of climate change on hydrology and corn yield in southeast Michigan, United States, and (2) assess the climate change impact on the optimum drain spacings under two drain depths of 75 cm shallow and 125 cm deep. Using DRAINMOD and climate projections (2030–2059) from nine general circulation models under the SSP2–4.5 pathway, the study predicted hydrological responses and economic returns for various drain spacing designs. The optimum drain spacing was determined as the spacing that maximizes economic return using historical (1994–2023) and future scenarios. Future predictions showed an increased annual temperature (9.6°C for historical vs 12.1°C for future), relatively stable annual precipitation (933 mm for historical vs 928 mm for future), increased evapotranspiration (21%), reduced drainage discharge (21%), and deeper water table (7%) compared to the historical. Drought stress was the primary driver of future yield reductions, averaging 25% for both drain depths. The number of dry days during the growing season is expected to increase in the future due to higher evapotranspiration and a deeper water table. Optimum drain spacings were projected to widen from 7 m to 11 m for shallow drains and from 12 m to 19 m for deep drains to mitigate drought stress. In conclusion, future climate conditions showed a yield decline, suggesting a wider drain spacing may be needed to mitigate the drier growing season.