Spatiotemporal Variations and Drivers of Agricultural Drought in the West Liaohe River Basin, China: A Structural Equation Modeling

Agricultural drought is among the most important stress factors threatening regional ecological security. The West Liaohe River Basin (WLRB), located on the eastern edge of the agro-pastoral ecotone in northern China, is a crucial region for both agriculture and livestock production. This study used Moderate Resolution Imaging Spectroradiometer (MODIS) data and the modified Temperature Vegetation Dryness Index (TVDI) to analyze the spatiotemporal variations in agricultural drought in the WLRB from 2001 to 2020. Pearson correlation analysis, Mantel tests, and the optimal parameters-based geographical detector identified key drivers of agricultural drought. Structural equation modeling (SEM) was used to quantify the direct and indirect effects of these key drivers. The results showed that 1) between 2001 and 2020, agricultural drought in the WLRB exhibited a spatial pattern characterized by increasing severity from the peripheral zones toward the central region. The average TVDI was 0.686 and decreased at a rate of 2.9 × 10^-3/yr, indicating an overall alleviation of agricultural drought. 2) Agricultural drought exhibited significant seasonality, with its intensity ranked as follows: winter > spring > autumn > summer. 3) Agricultural drought was primarily influenced by temperature (TEM), potential evapotranspiration (PET), and precipitation (PRE), with TEM exerting the strongest positive effect and PRE having the most significant negative effect. TVDI was positively correlated with PET and TEM in 80.50% and 70.27% of the study area, respectively, while it was negatively correlated with PRE in 79.73% of the area. This study provides insights into the spatiotemporal patterns and driving mechanisms of agricultural drought in the WLRB, offering a scientific foundation for drought mitigation and the promotion of sustainable regional development.