Research On The Remote Sensed Monitoring Of Drought In Chongqing Based On EOS-MODIS

In China, drought is one of the highest frequence meteorological disasters, with its long duration and large influence areas. It takes a great significance on the national economy, especially on the agricultural production. In the southwest of China, due to the complicated terrain condition, poor capacity of water storage in soil, uneven spatial and temporal distribution of rainfall and so on, regional and periodic droughts often occur in Chongqing. It brings great losses to the agricultural production and national lives. Therefore, it has an important practical significance on making use of 3S technology (GIS, GPS, RS) to monitor drought information, assess drought, take positive and effective measures to minimize losses, timely and accurately.The various remote sensing data about home and abroad for drought monitoring were collected in this paper. The drought monitoring models and their applications of the hilly terrain and the physiognomy which mixed with the karsts and non karsts landscape were studied, in Chongqing. Using the meteorological site data of 30 years and considering the temperature, precipitation and other factors, the temporal and spatial distribution of drought was studied based on the meteorological stations. Using the MODIS images, the three kinds of inversions models, such as the time series of vegetation index, vegetation supply water index and temperature vegetation dryness index, were analyzed. The drought model of remote sensing was finalized with soil moisture and meteorological data, at summer,2006.The main contents and conclusions were as follows:(1)Making use of the regression analysis with the elevation, temperature, precipitation, latitude and longitude from meteorological stations in Chongqing and neighboring provinces, the space extended model and the fine spatial distribution on drought frequency in each season were produced.. The results showed that, there were obvious differences among the various regions of Chongqing, and major droughts occurred in the late summer season from July to August.(2) The use of MODIS on composite vegetation index, from July to September, among 2000 to 2009, the time series of vegetation index were used to research and analyze the drought. The results showed that the enhanced vegetation index (EVI) took the better effect than the normalized vegetation index (NDVI), the time series of vegetation index in the time domain had a strong sensitivity, but weak in the spatial domain.(3) The use of MODIS on 8 days composite data, from July to September in 2006, the vegetation supply water index (VSWI) model was built. The adaptability validations of drought monitoring models were investigated using the relative soil water content. The results showed that the correlations of single-day MODIS product data were stronger than synthetic data of 8 days. There were some correlations between the elevation and the relevance of VSWI and soil moisture.(4) The use of MODIS on 8 days composite data, from July to September in 2006, the temperature vegetation dryness index model (TVDI) was build. The results showed that the correlations of TVDI constructed by daily data were greater than VSWI, Compared with land surface temperature, vegetation index reflected the ability of drought rather limited for the TVDI.(5) VSWI was the most suitable remote sensing monitor model in the study area in summer. There were five stages for the drought:arid outcrop-droughts occur-drought increased-drought severe-the remission in the summer of 2006, in Chongqing. In addition to a small part of southeastern region, therer was very serious drought in other regions.(6) With the land-use interpretation data in Chongqing,2006, the variations of drought between different land types were analyzed. The results showed that there was certain correlation between soil moisture and land use. With the geomorphologic data which divided by degree of roughness and altitude, the variations of drought between different geomorphology types were analyzed. The results showed that with increasing degree of elevation and roughness, the trend of drought conditions was weakened.