Risk Assessment And Zoning Of Agricultural Drought In Ji'an City

Since the 20th century,as global warming has continued to increase,droughts have occurred frequently in the southern region,causing huge losses.The Jitai Basin,as a high-risk area in Jiangxi,is also the region with the most cultivated land per agricultural population in the province.Therefore,this article takes Ji'an City as an example,analyzes the spatial and temporal distribution of precipitation,temperature,and standardized precipitation evapotranspiration index(SPEI),combined with historical drought data for nearly 60 years to verify,summarizes the characteristics and disaster mechanism of agricultural drought in Ji'an City.Combining the availability of data and the local situation in Ji'an City,17 indicators were selected to carry out a risk assessment of agricultural drought in Ji'an City,and proposed countermeasures for drought resistance in Ji'an City from irrigation districts,counties and cities.The conclusion is as follows:(1)From 1960 to 2018,precipitation,temperature,and SPEI values all showed an upward trend and were not significant.The periods of precipitation are 22a and 16a,the year of mutation is the 1970s and 1980s,and the regions with more precipitation are the west and northeast.The year of sudden temperature change is 2012,and there is no obvious cycle.The temperature in the Jitai Basin is relatively high and the temperature in Jinggang mountain is relatively low.Comparing and verifying the drought frequency and drought station ratio from the SPEI value evaluation with the historical drought situation,there is a good matching degree,indicating that the SPEI value is suitable for the analysis of drought characteristics in Ji'an City.The drought intensity in Ji'an City generally shows a downward trend.The drought frequency is between 25.4%and 37.3%.The regions with higher drought frequencies are Suichuan,Jizhou,Jishui,and Yongfeng.The drought stations in summer and autumn are relatively high,and are mostly global droughts.According to the verification of historical drought conditions,the drought-prone area coincides with the high-temperature area and is the Jitai Basin.Therefore,the main reason for the drought is higher temperature,followed by less rainfall.(2)The drought disaster risk assessment indicator system is divided into a factor layer and an indicator layer.The factor layer is the hazard of the disaster-causing factor,the vulnerability of the disaster-preventing environment,the exposure of the disaster-bearing body,and the ability of disaster prevention and mitigation.The bottom layer is the indicator layer.The disaster-causing factors are precipitation and evaporation;surface vulnerability,groundwater runoff,soil water content.soil type,elevation,and slope are selected for the vulnerability of the disaster-preventing environment;the exposure area of the disaster-bearing body is selected from the crop planting area and the food crop area.Ratio,farmland water use ratio,crop yield per unit;the number of drought-resistant equipment,the effective irrigation rate,the number of rural centralized water supply projects and the water supply capacity of the reservoir are selected for the capacity of disaster prevention and reduction.(3)Natural characteristics include hazards of disaster-causing factors and vulnerability of disaster-preventing environment.The hazard assessment results of hazards in Ji' an City indicate that the hazards are divided into 5 areas,the high-risk areas are Taihe,Qingyuan,Wan'an,and eastern Suichuan,and the other areas are below the medium-high risk areas.The upper part shows a downward trend from south to northeast and west.and the distribution characteristics have a huge relationship with the spatial distribution of precipitation.The assessment results of the vulnerability of disaster-preventing environment in Ji'an City are:the middle and high fragility areas,the high fragility areas are Ji'an County,Taihe,Suichuan,Wan'an,southeast Jishui,southeast Qingyuan,Jinggang mountain,Yongxin Less water runoff,lower soil water content,and other areas below the medium vulnerability.The vulnerability to disasters is higher in the west,south and east,and lower in the north and east.(4)Social characteristics include the exposure of disaster-bearing bodies and the ability of disaster prevention and mitigation.The exposure evaluation results of disaster-bearing bodies in Ji'an City are as follows:the exposure is divided into 5 levels,the medium and high exposure is Taihe,Ji'an County,Xiajiang,Xingan,Yongfeng;the high exposure is Jishui,and the other areas are below medium exposure.Because Jishui's four index values are higher.The exposure of the disaster-bearing body gradually increased from southwest to east.The capacity for disaster prevention and mitigation in Ji'an City is:medium and high capacity and high capacity are Anfu,Ji'an County,Taihe,Qingyuan and Wan'an.Other areas are below China's disaster prevention and mitigation capabilities.The disaster prevention and mitigation capability is higher in the central region,lower in the northeast and southwest,and the lowest is in the Jizhou district.(5)The distribution characteristics of the drought risk zoning in Ji'an City are:the drought risk in the Jitai Basin is higher,and the drought risk in the west and southwest is lower.The high-risk areas are Taihe and Jishui;Taihe is mainly affected by natural factors,with less precipitation and greater evaporation.Jishui is mainly affected by the exposure of disaster-bearing bodies and the vulnerability of the disaster-preventing environment.The area's surface water runoff is relatively small,and the proportion of crop planting area,crop yield and grain crop area is high.The medium and high risks are eastern Suichuan,Wan'an Ji'an County,Yongfeng and Xingan;the medium risk areas are Yongxin,Anfu,western Suichuan and Xiajiang;the medium and low risks are Jinggangshan,Jizhou and Qingyuan.The agricultural drought risk zoning in Ji'an City is in line with the actual situation,indicating that the drought risk assessment method and zoning established in this paper are effective.(6)According to the drought risk map and the results of field investigations,the following countermeasures were proposed from three aspects:irrigation area,county,and city:1)Strengthen water resources utilization,improve irrigation area management system,strengthen irrigation area daily maintenance,improve drought resistance facilities,correct reservoir Dispatch 2)Adopting water-saving irrigation measures to save agricultural water and increase drought-resistance service organizations 3)Add soil moisture stations to supplement soil moisture stations network and build a drought-resistance plan system.