Remote Sensing Monitoring of Farmland Drought Based on Vegetation Supply Water Index

The vegetation index retrieved from satellite remote sensing data and the surface brightness temperature are two key factors,which can illustrate the drought extent of vegetation-covered surface.The vegetation supply water index(VSWI),the ratio of normalized difference vegetation index to land surface temperature,is one of the effective methods to assess farmland drought with satellite remote sensing.The NOAA satellite data from 1995 to 2000 and the digital information of land application in Guigang city of Guangxi Province are temporarily analyzed in this paper.Typical crop representative areas are found and characteristic values of averaged maximum and minimum VSWI for those areas calculated.The drought index for paddy field and nonirrigated farmland is induced and analyzed.Based on the averaged VSWI values of typical representative areas,the drought level is divided and then remote sensing images of farmland drought are produced to assess the drought situation.Experiments indicate that the above method is able to remotely monitor the farmland drought in the moist and semi-moist areas.