Spatial variation in drought and its determining factors in Shendong mining region

【Objective】 The Shendong mining region is the largest coal mine in China. Extensive coal mining for many years has altered the geological landscape and disrupted ecology, leading to surface subsidence, drop of groundwater table, loss of soil moisture and nutrients, and landscape fragmentation in the region. This paper is to investigate the spatial variability in drought and its correlation to coal mining-induced collapses in the region. 【Method】 The analysis is based on temperature vegetation drought index (TVDI), and surface droughts measured from 2002 to 2018. Spatial variations in environmental factors and their effect on drought are analyzed using a geographical detector model by elucidating the response of drought to coal mining. 【Result】 TVDI had been consistently decreasing from 2002 to 2018, reaching the lowest point at 0.561 in 2018. Temporarily, May to August saw the most severe drought each year. Spatially, the southwest experienced higher drought severity than the northeast. The q-values obtained from the geographic detector analysis for precipitation, normalized vegetation index (NDVI), and soil type excepted 10% each year. Synergistic effects between these factors and others significantly improved the explanatory capacity of individual factors for spatial variation in the drought. The correlation coefficients between TVDI and precipitation and between TVDI and NDVI were -0.695 and -0.51, respectively. Average annual TVDI was higher in the subsidence areas than in the non-subsidence areas. 【Conclusion】 From 2002 to 2018, TVDI spatiotemporally varied in the region, and drought severity was higher and more prevalent in the southwest than in the northeast. Precipitation, NDVI and soil type are the factors that affected drought most. These factors combine to explain the spatiotemporal variation in TVDI more than by any signal factor. Furthermore, the interplay among precipitation, NDVI, soil type and other geographical factors impacts the spatial variation in TVDI. It is important to highlight that collapses in coal mining could have contributed to drought occurrence.