Vegetation net primary productivity variation characteristics and optimization path in inland river basins of arid areas driven by ecological water conveyance: A case study of the mainstream of the Tarim river

Under the backdrop of intensified climate change and human activities, the issues of downstream river cutoff and ecological degradation in arid inland river basins have become increasingly prominent. Ecological Water Conveyance (EWC) has emerged as a critical measure for improving the ecological environment and promoting vegetation restoration. This study establishes a comprehensive assessment framework for the dynamic changes in EWC and Net Primary Productivity (NPP) through trend analysis and partial derivative analysis, quantifying the contributions of climatic factors and human activities to NPP variations. The results indicate that from 2000 to 2022, the NPP in the mainstream of the Tarim River exhibited an overall improving trend, with 77.6% of the area showing an increase. Significantly enhanced areas (24.7%) were primarily distributed near the downstream water conveyance channels and certain upstream regions. The average contributions of climatic factors and human activities to NPP were 0.51 and 1.94 gC·m −2 ·a −1 , respectively, while in the downstream areas, they were 0.07 and 2.35 gC·m −2 ·a −1 , respectively, indicating that human activities are the primary driver of NPP growth in the downstream regions. The primary influence range of EWC is concentrated within 1.5 km of the river channel, with the contribution rate to NPP changes increasing from 51.6% to 85.5% between 2000 and 2015, but decreasing to 42.7% from 2015 to 2020, suggesting that vegetation recovery near the river has approached a bottleneck. In the future, it is necessary to optimize water conveyance strategies, expand the scope of benefits, and establish an efficient water delivery system to provide a reference for the sustainable development of similar arid inland river basins globally.