Research On The Remote Sensed Monitoring Of Agricultral Drought In The Lake Dongting Basin

Drought is one natural disasters often occures around the wold,which led to decreases of agricultural yield and shortages of food supply,and its long duration will make land resources degradation,water scarcity,ecological enviromental damage,restricting agricultural and sustainable development of society and economy.Therefore,it has an important practical significance on making use of RS technology to monitor drought information, assess drought happen scope and development degree and change trend,take positive and effective measures.Lake Dongting basin is choosed as study area. Vegetation Index and land surface temperature data were used from Moderate Resolution Imaging Spectroradiometer(MODIS) sensor and precipitation data from Tropical Rainfall Measuring Mission (TRMM) satellite as well,according to three different information about the drought sensitive degree, given the different weights, establish drought condition index (DCI).Using the DCI, agricultral drought and rice drought in Lake Dongting basin were studied from September to November in2008～2010.Firstly,Vegetation Condition Index(VCI)、Temperature Condition Index (TCI) and Tropical Rainfall Condition Index (TRCI) were used to establish Drought Condition Index (DCI) model,and the higher weight were assigned to the TCI and TRCI in the DCI model. The reasonable of DCI for drought monitoring was evaluated in Lake Dongting basin, using data from September to November in2009.Results showed that DCI was the better promising method in monitoring agricultral in South China.Secondly,using the DCI model, the spatio-temporal pattern of regional agricultral drought and rice drought in Lake Dongting basin from September to November were studied in2008～2010. Spatio-temporal pattern of DCI was compared with the real drought condition from the observatories around basin,thus Validity of DCI in drought evaluating were verified especially in South China that has a mountainous topography.Furthermore,by using of geo-data and land use maps,the rice fields information were extracted out with the rice growth in different phenophase,using the reflect data of MODIS, analyzed the characteristics of rice spectrum,and dynamic monitoring the rice drought were achieved.Innovations of this thesis lies in:(1)using additive combination of VCI and TCI from MODIS data and TRCI based on TRMM data, the DCI model have been set up,and the higher weight were assigned to the TCI and TRCI.(2)Research of information extraction of rice fields and achivement of agricultral drought and rice drought dynamic monitoring with DCI model in Dongting Lake basin.