河北省冬小麦干旱综合监测模型研究

Study on Comprehensive Drought Monitoring Model of Winter Wheat in Hebei Province

干旱是影响河北省冬小麦生产的主要灾害之一。为了客观地辨识、监测干旱的发生发展,针对河北省冬小麦干旱监测业务服务需求,开展冬小麦干旱综合监测模型研究,选取能反映土壤、作物、大气三方面干旱的土壤相对湿度指数、作物水分亏缺距平指数、降水量距平指数,采用层次分析法确定各指数权重系数,建立冬小麦干旱综合监测模型;应用1981—2010年唐山、涿州、定州、黄骅、深县、栾城、南宫、肥乡8个农业气象观测站资料,计算各站冬小麦干旱综合指数,并对其描述干旱的能力进行分析。结果表明:当不存在旱情时,各单一指数和综合指数均可正确反映,这种情况占总样本的17.6%。当存在旱情时,综合指数克服了距平指数不能反映灌溉对旱情的影响,及土壤相对湿度指数受灌溉影响,掩盖前期旱情的不足,比较客观地反映了旱情的发生发展情况,这种情况占总样本的67.6%;同时,综合指数也克服了距平指数对降水过度敏感的不足,既能反映降水对旱情的影响,又能反映降水大小对旱情的影响程度,较单一指数能更准确的反映旱情,这种情况占总样本的14.8%。

Drought is one of the main hazards for winter wheat production in Hebei Province. Aiming at the service demand of monitoring the winter wheat drought in Hebei Province, in order to objectively identify and monitor the occurrence and development of winter wheat drought, we designed the wheat drought monitoring model. Based on the analysis of the limitations of single drought index, the soil relative moisture index, crop water deficit departure index and precipitation departure index were applied in the model of winter wheat drought monitoring, because they could reflect the drought of soil, crop and atmospheric respectively. The weight coefficient of the three drought indexes were defined by analytic hierarchy method. Data were selected to analyze the accuracy of the composite index in characterizing winter wheat drought, while those data came from eight representative stations in Tangshan, Zhuozhou, Dingzhou, Huanghua, Shenxian, Luancheng, Nancheng and Feixiang in Hebei Province from 1981 to 2010. The results showed that： firstly, while there was no drought condition, the single index and composite index could reflect the situation, and the case was 17.6% of the total. Secondly, when the drought situation existed, composite drought index was able to reflect both the situation of irrigation, while the precipitation departure index could not reflect, and the situation of prophasedrought, thus it could reflect the drought situation, and the case was 67.6% of the total. Negative precipitation departure index and crop water deficit departure index were too sensitive to precipitation, and little precipitation would cover the real drought situation, as a result, they could not truly reflect the drought situation. The composite index could not only reflect the influence of precipitation on drought, but also reflect the influence degree, and the ease was 14.8% of the total.