Spatio-temporal analysis of drought in a typical plain region based on the soil moisture anomaly percentage index

Drought strongly affects the agricultural economy, most severely in plain regions, with prosperous agricultural development, which suffer huge economic losses. An effective index is required to describe the process of drought initiation, development, and alleviation, and soil moisture is a vital variable with respect to agricultural drought as a comprehensive variable. In this study, Jiangsu province was selected as a typical plain region, the VIC (Variable Infiltration Capacity) model was used to simulate soil moisture at a resolution of 0.125°×0.125°, and the soil moisture anomaly percentage index (SMAPI) was established for drought identification and investigation of drought spatio-temporal characteristics between 1956 and 2011. The results show that the VIC model built in our study is feasible, and the simulated 3-layer daily soil moisture database can be used in drought studies as an alternative to measured soil moisture. The droughts in the northern part of the province are more severe than those in the southern part, and Xuzhou is the most frequently affected city. There are no strong trends of drought duration in 13 cities of Jiangsu province. Among the 13 cities, drought intensity decreases as drought duration increases for the same drought area, and drought intensity decreases with drought area for the same drought duration. The methods used here in our study to build the VIC model for plain regions that lack closed basin hydrologic data may be helpful for further studies of VIC, and the regional analysis of drought can provide a powerful reference for regional drought prevention and resistance in Jiangsu province.