The Research On The Drought And Its Influence On The Production Of Grain In Jiangxi Province By Remote Sensing

Drought observation in Jiangxi province usually makes use of rainfall,relative moisture of soil, and other weather datas to estimate drought indirectly.Observation by point which illustrates drought condition of all the area can't meet the require of drought observation in large scale.So this paper is main to do research on the drought and its influence on the production of grain in Jiangxi province by Remote Sensing.Water Deficit Index is based on the theory of regional energy balance,which extends further based on CWSI(Crop Water Stress index) theory with strong physical foundation.Under the condition that we hypothesize land surface temperature is linear weighted by temperature and surface temperature of soil and there doesn't exsit sensible heat exchange between soil and vegetation, WDI take advantage of spectrum vegetion index gained from visible light and near infrared and land surface temperature information obtained from thermal infrared to estimate the status of relative moisturein the field.The paper gets the Water Deficit Index by Enforced Vegetation Index and Land Surface Temperature,analyse the feasibility of Jiangxi drought with Water Deficit Index by rainfall datas of weather station and soil surface observing moisture.It classifies the Jiangxi drought with different ranks,gains drought ranking distribution curve all over the province and calculates drought areas of different drought ranking region.It studies space-time distribution and disaster degree of Jiangxi drought between 2004 and 2006 from macroscopic perspective.The paper estimates drought influences in grain planting areas and products by analyzing the relativity of Water Deficit Index,rainfall datas and grain planting areas and products.From this paper we gets the main conclusions that:(1) We estimate Jiangxi drought ranking by Rainfall Percent and Drought Area Ratio,the result shows that Spring is the wet season all over the province,in the Summer drought is prone to occur and there are few droughts in Autumn and Winter. The drought is very heavy during 2003 and light in 2004.(2) We validate the Water Deficit Index model by rainfall datas at one time,the outcome indicates that the Water Deficit Index is more sensitive and to suitable for observing and estamating the drought in Jiangxi from winter to spring.(3) We classify the drought into four rankings:wet,normal,light and heavy,and obtain the drought remote sensing observing charts of every month and every year by density division based on the analysis of Water Deficit Index adaptability. The analysis result demonstrates that in 2002-2004 drought is usually occurred in Summer and Autumn in Jiangxi province and distributes unevenly.(4) The relativity between drought index and grain planting: drought caused by rainfall takes great influence on grain planting in Jiangxi.The output and saw area of grain in Jiangxi Province is mainly based on the serious degree and distribution of drought.