Fuzzy evaluation system of agriculture drought disaster risk and its application

Abstract: Droughts happened frequently in the past few years and caused great loss in economy in parts of China, especially in agricultural production. Analysis of drought risk mainly used qualitative analysis and theory research, but quantitative analysis is few in previous studies. Therefore, it is of guiding significance to establish a fuzzy comprehensive index system taking regional agricultural drought risk as the evaluation targets. To give a quantitative assessment of agriculture drought, a calculation method for regional agriculture drought disaster risk indicators based on analytic hierarchy process (AHP) and fuzzy comprehensive evaluation (FCE) was put forward in this paper. This method includes the identification of agricultural drought disaster indicators, the determination of index weight and the calculation of drought risk comprehensive evaluation index. For the calculation process, firstly, the agricultural drought disaster indicators were identified. The agriculture drought disaster risk indicators system divided into four main indicators, namely hazard indicator (H), exposure indicator (E), vulnerability indicator (V) and drought resistance ability indicator (RE). The first three indicators are objective, while the last one is subjective which includes the influence of human activity. Secondly, the agricultural drought disaster indicators were determined. The indicators were determined based on the social economy, hydrological and meteorological data. Meanwhile, some sub-indicators were selected to form the lower hierarchy of the risk indicators system, and the weights of sub-indicators were calculated by AHP method from the judgment matrices of each main indicator. Finally, drought risk comprehensive evaluation index was calculated. With the normalization of sub-indicators and the calculation of FCE equation of agriculture drought disaster risk, the comprehensive risk level could be calculated. Taking the eight counties of Chengde City in Hebei Province as an example, the comprehensive risk level for each county was analyzed based on the above method. From the distribution of agriculture drought disaster risk indicator, the results showed that the drought risk of counties in the upstream area was generally higher than that in the downstream area and the drought resistance ability was of great difference for each county, which were consistence with some literature. The value of comprehensive risk level was 79, 33 and 16 for Weichang county, Fengning county and Longhua county in the upstream area, respectively. The value of comprehensive risk level was 11, 14 and 8 for Chengde county, Pingquan county and Luanping county in the midstream area, respectively. The value of comprehensive risk level was 3 and 3 for Xinglong county and Kuancheng county in the upstream area, respectively. Also, the sub-indicators of the four indicators varied obviously from county to county, which can provide a basis for targeted drought mitigation activities. Weichang county had a high value of hazard indicator (H=5.1). Fengning county had high values of exposure indicator (E=5.4) and vulnerability indicator (V=5.1). Longhua county had a high value of hazard indicator (H=5.4). Despite the deficiency of this method, including the difficulty of risk verification and the demand of high quality regional data, the results confirmed the rationality of the evaluation method. This method could be used to provide decision support and quantitative basis for the development of effective drought resistance activities.