黄土高原不同水平年旱涝时空分布特征分析

全球气候变暖大背景下，黄土高原总体呈现暖干化趋势，未来干旱还可能会加剧。为了全面了解黄土高原旱涝时空变化特征，为黄土高原应对旱涝灾害提供决策依据，根据黄土高原及周边263个气象站的降水数据划分降水水平年，以标准化降水指数（SPI）为指标，分析了黄土高原地区不同水平年年际及年内旱涝特征。结果显示，黄土高原在丰、平、枯水年均有不同程度的干旱发生。丰水年黄土高原干旱面积占5.7%，雨涝面积占40.9%；平水年干旱面积占12.7%，雨涝面积占19.3%；枯水年干旱面积占44.4%，雨涝面积占17.9%。不同水平年的干旱区域存在差异。不同水平年内春旱较重，丰水年和平水年雨季开始后干旱逐渐缓解，枯水年雨季不能有效缓解春季以来的干旱，且秋涝明显，各水平年年内干旱的时空分布存在显著差异。不同水平年年际和年内旱涝差异大且变化频繁，为了确保黄土高原农业生产旱涝保收，应合理布设小型水利工程与田间灌溉设施。 

Spatial and Temporal Distribution of Drought/Flood on the Loess Plateau in Different Hydrological Years

Changes of global climate will lead to more uncertainty of annual precipitations in Loess Plateau, which is a critical factor for causing droughts or floods in that area． In order to design better strategy to manage water resource in different hydrological years, special and temporal distribution of drought and flood in Loess Plateau was analyzed． Precipitation data from 263 meteorological stations were used to identify typical hydrological years, including wet year, normal year and dry year． Then Standardized Precipitation Index（SPI）was calculated as an indicator for droughts and floods． Results showed that droughts occurred in all kinds of hydrological years． In wet year, drought area, flood area took up 5.7% and 40.9%, respectively． In normal year, drought area and flood area accounted for 12.7% and 19.3%, respectively． However, drought area took up 44.4% and flood area took up 17.9% in dry year． Spatial distribution of droughts in wet year, normal year and dry year was obviously different． Spring was usually dry in all kinds of hydrological years． Drought area in spring would decrease after beginning of rainy season in wet year and normal year, however rainfall in rainy season of dry year could not alleviate spring drought effectively． What’s more, autumn in dry year was wet． According to results, drought and flood were frequent in Loess Plateau, allocation of water conservancy facilities and field irrigation facilities in Loess Plateau were critical for agriculture and ecosystem in Loess Plateau．