Researches On Agricultural Drought Risk Assessment In Shaanxi Province,China

Drought disaster in Shaanxi province severely restricts the development of local agricultural economy, known as " drought of nine years out of ten ", agricultural drought risk assessment is the basis of scientific development of drought mitigation strategies. Based on the analysis of drought characteristics in Shaanxi province, using principal component analysis and expert index to determine evaluation index, using AHP to determine index weight and building agricultural drought risk assessment model based on disaster risk theory. The main results are as follows:(1) The water deficit index of winter wheat in Shaanxi province from 1994 to 2013 showsed a linear rising trend, and winter wheat growth is facing more and more serious drought threat. In recent 20 years, the variation trend of precipitation departure index in Shaanxi province was basically consistent with the three natural regions ( north Shaanxi, central Shaanxi and south Shaanxi ). there were two major positive in 2003 and 2011. However, the average number of anomaly in the three regions was more than positive, indicating that there is a downward trend of precipitation in Shaanxi province during the study period.(2) The results of the analysis of the main components showed that the first four principal components accounted for 91.80% of variance (greater than 85%), showed that the first four principal components include all measurements of the main information. The index of the component value of the extracted eigenvector is greater than 0.2, and the first, second, third and fourth principal components reflect the information of nine, six, four and five indexes respectively. In addition, the principal component analysis is used to index selection, can decrease the number of evaluation index reflects certain indicators selection advantage, but easy to overlook the correlation between indicators. And expert consultation method relies on experts rich theoretical knowledge and practical experience, can accurately select suitable for local risk assessment indicators, but vulnerable to expert knowledge level and personal hobbies such as subjective factors. In the method of principal component analysis and expert consultation method, the evaluation index is more scientific.(3) The comprehensive index evaluation model based on disaster risk theory can accurately assess the agricultural drought risk in Shaanxi province.the results showed that the risk of agricultural drought in Shaanxi province is gradually increasing from south to north.From 2009 to 2013 the drought risk of agriculture in northern Shaanxi showed a slight downward trend, the basic stability in central Shaanxi, and a sharp increase in southern Shaanxi.Mainly affected by the precipitation, grain area, modulus of water production and economic level in various regions.