Research On Agricultural Drought In Hubei Province Based On Modifying Palmer Drought Severity Model

Recently drought becomes more and more serious accordingly as the globalenvironment is deteriorating and water resource is getting shorter. Agricultural drought isone of the most serious risk factors of agriculture in Hubei province. To make anagricultural drought index is the basic of agricultural drought research. The purpose ofthis paper is to research the spatial and temporal distribution characteristics of agriculturaldrought in Hubei province based on developing an agricultural drought severity modelwhich can explain the procedure, the cause and the severity of drought.The paper, which is based on the Palmer Drought Severity Model of America and themodified Palmer Drought Severity Model (1985) of china, and combined in the actualconditions of Hubei province closely, had got further profound and systematic research onevaluation index system and assessment methods in agricultural drought. The PalmerModel has been further modified in the methods of choosing stations, calculating thepotential evapotranspiration and available water capacity of the soil (AWC), correctingfor K, and compartmentalizing PDSI's grade as agriculture drought index of Hubeiprovince. What's more, the main characterizations of the drought in Hubei province wereanalyzed through calculating the monthly Palmer Drought Index of 65 stations fromSeptember, 1964 to September, 2004 and verifying the applicability of the furthermodified Model of Hubei.The main conclusions can be summarized as follows:1. The results indicate that the modification method of correcting for K dividuallyand the criterion of PDSI's grades as agricultural drought index is more logical, thefurther modified Palmer Drought Severity Model of Hubei province is a quantificational,accurate and applicable model for evaluating agricultural drought in Hubei province.2. The agricultural drought frequency decreased from northwest and northeast to themiddle part of Hubei gradually, and then increased form the middle part to southwest andsoutheast gradually. It shows that the agricultural drought frequency isolines runedparallel to the weft. The main drought grade is slight or middling drought in most stations,contrarily, it is severe and extreme drought in other stations. 3. Deep summer drought appears most frequently as single-season agriculturaldrought, and deep summer-autumn drought appears most frequently as multi-seasonagricultural drought. The same feature of each seasonal agricultural drought is that thespatial distribution of frequency has inverse relations with height above sea level.4. The month with the maximum frequency of agricultural drought occurres fromJuly to September in Hubei. The drought takes place mostly in the middle and the eastparts of Hubei in July or August, while the northwest and the southwest regions and thesouth of Jianghan Plain in September. But in October or November, the part of northwestand hillock zone of north Hubei suffered.It is of great practical importance to establish a quantificational, accurate andeffective method for agricultural drought research in this region and apply the PalmerDrought Severity Model to agricultural drought research through this work. Furthermore,the agricultural drought characterizations of Hubei province are the theoretical part forfighting a drought, adjusting cultivation structure, optimizing crop distribution andcultivate system, using water resource effectively, and building the socialist newcountryside.