西北地区农业旱灾与预测研究

Prediction on Agricultural Drought Disasters in Northwest China

西北地区干旱灾害在中国乃至世界上具有代表性,常常对农业生产、社会经济和人民生活带来巨大威胁。利用西北五省区(陕西、甘肃、宁夏、青海、新疆)1951～2000年的50年农业旱灾面积统计资料,分析了农业旱灾的时空强度变化。表明西北地区农业旱灾有增加趋势,以20世纪90年代增加最明显。利用西北地区均匀分布的40个站点50年的降水和气温资料,采用变换的Z指数法,探讨了干旱强度和地表径流量的时间变化与西北地区农业旱害的关系。表明降水量的减少及河川径流枯期与农业旱灾面积负相关关系密切。应用波谱分析与逐步自回归方法,分别建立了西北地区干旱指数的拟合回归预测模型,农业旱灾面积、成灾面积和绝收面积预测模型,并对西北地区干旱灾害的趋势进行了预测。表明西北地区干旱灾害在21世纪前十年有所减缓。经检验,模型预测效果良好,根据预测结果可以采取有针对性的减灾措施,减少西北地区农业灾害损失。

Drought disasters occur frequently in northwest Chain and are typical in China and even in the world. Severe droughts affect seriously the agricultural production, social and economic development, ecology and people's general life. In this paper, the temporal and spatial change of the intensity of agricultural drought disasters is analyzed based on the 50 year statistical data of precipitation, temperature, and drought disaster areas in northwest China (including Shaanxi Province, Gansu Province, Ningxia Hui Autonomous Region, Qinghai Province and Xinjiang Uygur Autonomous Region) during the period from 1951 to 2000. The results show that the drought disasters have increased and the disaster areas have been enlarged since recent 50 years, especially since the 1990s. In spatial distribution, drought disasters are extremely serious in Shaanxi Province and Gansu Province. By contrast analysis, the relationship between the agricultural drought disasters and the drought intensity and temporal distribution of surface water is researched, and it is considered that the agricultural disaster areas are closely related to the reduction of precipitation and runoff volume in dry season. The fitting regression prediction models of drought indexes are separately developed for predicting the drought disaster areas and the areas of total crop failure in the different regions in northwest China by using spectrum analysis and self regression analysis. The prediction results with the models accord well with the actual data, which can be used for taking some measures in drought reduction.