Rational Planning of Land Use Can Maintain Water Yield Without Damaging Ecological Stability in Upstream of Inland River: Case Study in the Hei River Basin of China

Upstream inland rivers provide most of water resources for midstream and downstream in arid and semiarid regions. From the perspective of ecological rehabilitation, it is necessary to simultaneously ensure upstream streamflow while still maintaining economy-ecosystem balance in upstream. However, vegetation dynamics effects caused by ecological rehabilitation cannot be well evaluated in previous studies due to the sparseness of observations at regional scales. With increased availability of vegetation and hydrological data, it is now possible to explore the relationship between water yield and ecological balance affected by vegetation dynamics. This study takes Upper Hei River Basin, part of the Asia's water tower-the Qinghai-Tibet Plateau, as an example and uses the Eagleson's ecohydrological model to explore the effects of vegetation dynamics on streamflow and ecology in growing seasons during 1992-2015. We compare scenarios with and without vegetation changes and find that there is limited evidence that ecological rehabilitation could enhance water yield. Approximately 51.31% of Upper Hei River Basin vegetation cover (M) tends to deviate from ecological optimization state compared to equilibrium vegetation cover (M-eq). In order to explore ways to ensure streamflow and maintain ecology, different vegetation scenarios are simulated. Results show that on average, grazing in area whereMis larger thanM(eq)could increase streamflow by approximately 7.3%/year and planting trees in other area could increase streamflow by approximately 2.9%/year. Therefore, effective control on vegetation dynamics can simultaneously ensure streamflow and maintain ecological balance, which can also provide guidance and theoretical support for upstream inland river planning.