A new model for simulating root water uptake by vegetation under the impact of a dynamic groundwater table in arid regions

Abstract Ecological water conveyance is an effective measure to mitigate or reverse vegetation ecosystem degradation in arid regions, which can lead to frequent fluctuations in the groundwater table. The depth of soil water that vegetation takes up varies in response to groundwater table fluctuations in arid environments. To better characterize the root water uptake process under dynamic changes in the groundwater table in arid regions, this study proposed a new model for simulating root water uptake. The model reduces the dominant effect of root density on water uptake by introducing a correction factor and accounts for the effect of changes in the water content profile on root water uptake in arid areas. The new model was incorporated into the HYDRUS code and tested against the monitoring data of typical vegetation in the arid region of northwestern China. The results demonstrated that the soil water content simulated by the new model matched well with the observed data, which was consistent with the water uptake process under the fluctuations of the groundwater table at the study site. Compared with other models, this model can flexibly alter water uptake layers according to soil moisture conditions in arid conditions, thus providing a new method to depict the dynamic process of water uptake influenced by fluctuations in the groundwater table.