Model Estimation of Water Use Efficiency for Soil Conservation in the Lower Heihe River Basin, Northwest China during 2000–2008

There has been very limited research on water use efficiency for soil conservation (WUE-SC) in typical water scarce regions such as the lower Heihe River Basin, where there is serious wind erosion and the soil conservation service plays a key role in guaranteeing the ecological safety of Northern China. The soil conservation service, which was represented by the soil conservation amount (SC), was first estimated with an experiment-based model in this study. Then, the WUE-SC (<i>i.e.</i>, SC/ET) was calculated on the basis of evapotranspiration (ET) data, and management implications were finally discussed. The results indicated the WUE-SC ranged between 0–98.69 t mm⁻¹, and it first decreased and then increased on the whole during 2000–2008. Besides, the inter-annual variation of WUE-SC was mainly due to change in the potential soil loss. In addition, the WUE-SC showed significant spatial heterogeneity, and the average WUE-SC of the whole study area was very low due to spatiotemporal inconsistency between the potential soil loss and the vegetation coverage rate. Although there are some uncertainties, these results still can provide local managers with valuable information for water resource utilization and ecosystem management to improve water use efficiency.