Effect of climate change on the contribution of groundwater to the root zone of winter wheat in the Huaibei Plain of China

Abstract

Winter wheat is the predominant crop in the Huaibei Plain of Anhui Province, China. The Huaibei Plain has a transitional climate and a shallow water table. As global warming accelerates, climate change in the area may impact agricultural production. In shallow groundwater regions, capillary rise can be large, and it can act as an important water resource for crop use. However, it is not clear how climate change will impact groundwater depths and crops. Based on local weather data from 1960 to 2010, a general circulation model, HadGEM2-AO, which performed best in simulating precipitation in the study area, and three Representative Concentration Pathways (RCPs, RCP 2.6, RCP 4.5 and RCP 8.5), the validated numerical model HYDRUS-1D was used to estimate the daily groundwater contribution to the crop root zone in 2011–2100 of different hydrological growing seasons. The largest groundwater contribution and deep drainage occurred at a water table depth of 1.5 m. The groundwater contribution to crop root zones was largest for RCP 2.6, and the deep drainage was largest for RCP 8.5. The results indicated that climate change could alter the distribution of the groundwater contribution in each growing period. Meanwhile, the phenophases of winter wheat for RCP 2.6 were delayed while they were advanced for RCP 4.5 and RCP 8.5. In wet and normal seasons, there was no need for irrigation for RCP 4.5 during the whole growing season. However, in a dry season, a small amount of irrigation was still needed during the maturity stage for RCP 2.6. In general, the total irrigation amounts needed for winter wheat growth were reduced for all hydrological conditions with the three RCPs.