【摘要】 根据1951—2000年中国西北五省区(陕西、甘肃、宁夏、青海、新疆)降水资料,1951—1994年主要农作物旱灾面积和粮食减产资料,建立了干旱等级指标、农业旱灾指标、因旱粮食减产指标体系,分析了西北干旱灾害的影响趋势。结果表明:西北干旱和农业旱灾呈增加趋势,以20世纪70、90年代最严重,农业旱灾以重大旱灾事件为主,其空间变化以西北东部干旱灾害严重。采用谐波和功率谱方法分析西北干旱周期,建立了拟合预测回归模型,并对西北干旱灾害进行影响预测,表明21世纪前十年西北干旱灾害有减缓趋势。更多还原

【Abstract】 In this paper, the index systems of the agricultural drought and decrease percent of grain crop are established.The trend and influence of drought in the region is analyzed based on the 50 years(1951—2000)statistical data of precipitation and 44 years (1951—1994) agricultural drought of the region, including five provinces: Shaanxi, Gansu, Ningxia, Qinghai, and Xinjiang.The result shows that the drought disaster is increasing and the most serious were in 1970s and 1990s, and main agricultural drought is great disaster incidents.The regression prediction equation of drought grades and agricultural drought areas grades are set up by the harmonic wave method, and forecast the drought will lighten during the first 10 years of 21st century.更多还原