Dynamic assessment of vegetation ecological water demand in Manas River Basin

Abstract

[Objective] To address the issue of ecological water shortage in inland river basins within the arid regions of northwestern China, the Manas River Basin is selected as the study area to assess the spatiotemporal dynamic changes of vegetation ecological water demand and to reveal the interaction mechanism of natural and human-driven factors, thereby providing a scientific basis for the optimal allocation of regional water resources. [Methods] Based on the land use data of the Manas River Basin, the vegetation area was extracted. An improved Penman-Monteith model, coupled with vegetation coefficients and soil moisture limitation coefficients, was employed to construct a calculation framework for vegetation ecological water demand. Combined with the geodetector, the influence of climatic and human factors on vegetation ecological water demand was analyzed. [Results] From 2000 to 2020, the vegetation coverage area decreased at a rate of 1 047. 9 km² per decade, and the vegetation ecological water demand declined at a rate of 8. 88×10⁸ m³ per decade. Land use was identified as the core driving factor of the changes in the ecological water demand of vegetation in the study area. The q value remained consistently stable within a high level ranging from 0. 93 to 0. 96. A nonlinear enhancement effect was observed between land use and climatic factors. [Conclusion] The study shows that the changes in vegetation ecological water demand in the Manas River Basin are mainly driven by the coupling of land use and climatic factors, and the changes in grassland area dominate the trend of total water demand. The conclusion can provide a reference for the management of vegetation ecological water demand in similar river basins in arid regions.

Keywords

vegetation ecological water demand / improved Penman-Monteith model / geodetector / Manas River Basin / land utilization / vegetation area / spatial and temporal distribution / influencing factors