Comprehensive monitoring model for agricultural drought and its application based on spatial information

To improve the accuracy of the agricultural drought monitoring, the comprehensive monitoring model coupled with the remote sensing data and meteorological data was used. This model was established based on the relationship between the standardization vegetation supply water index (VSWIS), the comprehensive precipitation index (CPI) and the synchronous soil moisture data measured in the study area. The VSWIS was suitable for monitoring drought at high density vegetation area, and the CPI was suitable for monitoring drought at tropical area. The root mean square error (RMSE) of the model was 4.65% and the relative root mean square error (RMSEr) was 19.28%. Furthermore, the model was used to evaluate the change of the agricultural drought in Hainan island from October 2004 to January 2005. The results indicated that the drought in the study area were significantly different. Overall, the drought in the west and north were more serious than that in the east and south of the island respectively, and the drought in the plain was more serious than that in the mountain area. In terms of the time changes, the drought approached maximum in early December 2004. Until late January 2005, the drought was still serious. The heavy drought area of paddy, upland and special woodland accounted for 59%, 61% and 20% respectively. Crop growing was constrained obviously by this drought. Compared with last year, the value of the accumulated normalized difference vegetation index (NDVI) was reduced by 6.34%, and yield of the natural rubber was reduced about 1.16×104t from October to December in 2004. The research provides a reference for monitoring agricultural drought.