Influence of ecological restoration on regional temperature-vegetation-precipitation dryness index in the middle Yellow River of China

Drought is an important disaster factor disturbing the stability of the ecosystem in the middle reaches of the Yellow River (YRM). In this study, the spatiotemporal distribution of drought in the YRM from 2000 to 2021 was quantitatively investigated by constructing the TVPDI (Temperature-Vegetation-Precipitation Dryness Index), and its driving mechanism was explored. The results show that: (1) a significant decreasing trend was observed in the regional annual TVPDI of the YRM, while the autumn TVPDI index showed an increasing trend during 2000-2021. (2) Plants are more susceptible to drought during the growing season. (3) Drought in YRM showed significant spatial heterogeneity, and the high gully area in the Loess Plateau and the earth-rocky mountain areas were less affected by drought than other regions. (4) The Structural Equation Model (SEM) indicated that regional soil moisture and vegetation coverage have a direct influence on regional TVPDI variation. This study has explored the regional differences of drought in different seasons and landforms in the YRM, providing a basis for carrying out targeted seasonal ecological management and refining regional environmental governance, as well as a reference for formulating differentiated ecological restoration and water resource allocation strategies according to local conditions.