Risk assessment and division of loss caused by drought for main crops in Longdong of Gansu Province | 陇东地区主要农作物干旱灾损风险分析及区划

صينى. 研究陇东地区冬小麦和春玉米种植的干旱风险，为指导该区农业生产的合理布局和有效地进行防灾减灾提供科学依据。从陇东主要农作物产量灾损角度出发，利用作物产量资料和气象资料，对历史干旱灾损情况（干旱分布、干旱发生强度和频率、干旱灾损分布）、受灾体种植面积比例和当地产量水平等方面进行综合分析，建立干旱灾损风险评估模型，确立综合区划指标，并进行干旱灾损风险区划。陇东多数县（区）冬小麦、春玉米因旱减产率大于20%的年份分别超过20%和14%；冬小麦、春玉米生育期间各类干旱发生频率分别为53%～94%和34%～80%；环县是陇东地区干旱发生最多，重度、极重度干旱发生频率最高的地区，冬小麦、春玉米干旱灾损率最大值均在环县，分别大于30%和20%；根据标准化风险指数将陇东冬小麦、春玉米种植区域分为低、中、较高和高4个风险区，对应的标准化风险指数（Ei）冬小麦分别为：Ei≤0.1，0.1＜Ei≤0.3，0.3＜Ei≤0.5，Ei＞0.5，春玉米分别为：Ei≤0.2，0.2＜Ei≤0.5，0.5＜Ei≤0.7，Ei＞0.7。陇东冬小麦和春玉米干旱风险分布自南向北逐渐增加,呈纬向分布；陇东北部是高风险区，中北部是较高风险区，中南部是中度风险区，东南部是低风险区。

إنجليزي. The drought risk of main crops in different areas of Longdong was studied to provide science gist for making rational distribution of planting to reduce loss of disasters effectivly. Based on the crops’ yield loss caused by drought, using the long term yield data of main crops and meteorological data in Longdong area, the loss in history caused by drought (drought distribution, intensity and frequency, and distribution of loss caused by drought), percentage of planting area and local yield level of crops, etc. were analysed. There were more than 20% and 14% years respectively in most areas of Longdong in which the yield reduction caused by drought was more than 20%; The frequency of various types of drought occurred during the growth period of winter wheat and spring corn was 53%C94% and 34%C80% respectively. Huanxian was the place where the frequency of drought, especially that of the severve and extreme drought, was the highest; The maxium of loss rate in Longdong caused by drought appeared in Huanxian too, which was more than 30% and 20% respectively; According to the comprehensive risk division index, Longdong was divided into 4 risk areas: the lowest, the moderate, the higher and the highest, and the corresponding risk index of winter wheat was Ei≤0.1, 0.1＜Ei≤0.3, 0.3＜Ei≤0.5 and Ei＞0.5 respectively, and the corresponding risk index of spring corn was Ei≤0.2, 0.2＜Ei≤0.5, 0.5＜Ei≤0.7 and Ei＞0.7 respectively. The results indicated that both risk distribution of loss caused by drought for winter wheat and spring corn increased from south to north. North of Longdong was the highest area, middle and north the higher area, and middle and south the moderate area, while the lowest area was located in south of Longdong.