Soil Moisture Dynamics Across Landscape Types in an Arid Inland River Basin of Northwest China

s: A combination of field measurements, continuous monitoring, and numerical modeling were used to evaluate soil moisture regimes at four sites across a landscape gradient of the Heihe River Basin (HRB). Recorded data of precipitation, irrigation, and floods were used to build the model, and an optimization technique was employed to calibrate the parameters. Based on the optimized parameters and estimates of future scenarios, the modeling structure was employed to predict the changes in the growing-season soil moisture regimes due to climate change and intensive management. The results suggest that the upper-reach Yeniugou and Xishui sites will become wetter due to alterations in the precipitation regime, and this trend could be strengthened by the expected amplified interannual variability. Precipitation features at middle-reach Linze and lower-reach Ejina, however, are not expected to change in the future. We assumed that a more water-saving irrigation system will replace the current traditional one, and hence the soil moisture probability density function (pdf) at the Linze site would tend to be narrowed to ranges around either the wilting point or the point of incipient water stress, depending on how the intervention point and target level are settled. Ejina is expected to experience the most extreme ecological conversion effects in the future, and soil moisture would be more frequently recharged by water delivery. However, the soil moisture regime would not change much due to the poor water-holding capacity and intensive evaporation. The revealed patterns and predicted shifts in soil moisture dynamics could provide a useful reference for identifying robust long-term water resource management strategies for the HRB.