陕北黄土高原降水的变化趋势分析

利用1951-2001年陕北黄土高原24个测站的降水资料,采用累计距平、线性趋势估计及Mann-Kendall检验等方法,分析了陕北黄土高原降水时空变化特征.结果表明:陕北黄土高原地区年平均降水南多北少,近51年来降水总体上呈减少趋势.北部长城沿线降水减少,中部(延安以北)与南部(延安以南)降水略有减少,府谷和横山、子长、延长一带降水减少最显著.3个区域降水量的年内分配过程差异较大,中部的春季、北部的夏季及南部的冬季降水减少,其它区域及季节降水变化基本平稳,增减幅度不大.

Analysis on the Change Trend of Precipitation in North Shaanxi Province in the Loess Plateau

Because of the peculiar geographical location, precipitation is the main source of water resources in the hess Plateau, so the spatiotemporal distribution and change of precipitation affects directly the spatiotemporal distribution and change of water resources and land use. In north Shaanxi Province, the climate change is sensitive, the ecological environment is vulnerable, and the production of agriculture and animal husbandry and the ecological environment rely strongly on the climatic conditions. In this paper, the spatiotemporal change of monthly, seasonal and annual precipitations in north Shaanxi Provinoe in the Loess Plateau is analyzed using cumulative anomaly, linear trend estimation and Mann- Kendall test based on the precipitation data observed by 24 observation stations in the plateau during the period from 1951 to 2001. The results show that the annual precipitation decreases from the south to the north in north Shaanxi Province in the Loess Plateau, and it has been in a decrease trend since recent 51 years. The armual precipitation decreases in the northern part of north Shaanxi Province, it decreases slightly in the central and southern parts and significantly in the Fugu, Zichang and Yanchang regions. Drought has frequently occurred since the 1990s. Seasonal precipitation varies significantly in these 3 regions, that is it decreases in the central region in spring, in the northern part in summer, and in the southern part in winter, and the change of precipitation in other regions and seasons is basically steady.