中文摘要：

不同等级降水与侵蚀性降水对水土保持有重要意义,为了更好地建设黄土高原生态屏障,亟须对马莲河流域降水特征进行详细分析。收集到马莲河流域1961—2010年西峰国家基准站、环县国家基本站和华池、庆城、合水、宁县、正宁5个国家一般站的日降水观测数据,使用PMF方法,对数据进行均一化检验,确保数据质量。采用基本气象水文统计方法,研究流域降水统计特征。运用气候倾向率、Mann-Kendall检验、滑动T检验、累积距平和Morlet小波变换等方法,分析流域降水趋势、突变点和周期等特征,同时分析侵蚀性降水、不同等级降水日数和降水强度的变化特征。结果表明：1）马莲河流域多年平均降水482 mm,四季降水分别占年降水量的18%、53%、27%和2%,侵蚀性降水占年降水57%,降水变异系数为0.19,流域降水〉400 mm的保证率为72%,〉500 mm的保证率为38%;2）1961—2010年马莲河流域降水与侵蚀性降水均呈减少趋势,春、秋季降水呈减少趋势,冬季降水呈增加趋势;3）降水的突变点不明显,1992年之后,降水呈减少的趋势,年和四季降水有19、11、4和2 a左右的主周期;4）中雨和小雨是马莲河流域主要降水形式,1961—2010年,降水减少是中雨和小雨显著减少引起的,降水强度与侵蚀性降水强度呈增强趋势,降水日数的减少对降水强度的增加有重要影响。马莲河流域侵蚀强度并未随雨量的减少而减弱,降水侵蚀风险没有减小,水土保持工作需要持续深入,水土保持与荒漠化治理刻不容缓。

英文摘要：

[Background] The Loess Plateau is one of the most serious soil erosion areas in China,and it is also an important region of ecological management and constructing ecological defense. It has proved that the small watershed is the basic unit of flood control and soil conservation in the Loess Plateau,and it plays a basic role in the construction of the ecological barrier on the Loess Plateau. Rainfall is the main erosion force of soil erosion on the Loess Plateau,and it is also an important guarantee for the ecological environment construction in the Loess Plateau,and also an important factor for the social and economic development for the river basin. The temporal and spatial variation characteristics of different grades precipitation are particularly important to assess the risk of soil erosion and geological hazards. TheMalian River Basin is located in Longdong Loess Plateau,belonging to the middle reaches of the Yellow River,is a first tributary of the Jinghe River. Therefore,the variation characteristics of precipitation in the Malian River Watershed in the Loess Plateau is worthy of further study of the problem. [Methods]Daily rainfall data from 1961 to 2010 at Xifeng National Base Station,Huan County National Basic Station and other 5 general stations were collected among the Malian River Basin. In order to ensure the quality of the data,the PMF method was used to examine homogenization. The statistical characteristics of precipitation in the river basin were studied using the basic meteorological and hydrological statistics method. The variation trend,abrupt change and periods of precipitation were analyzed by applying climatic tendency rate,M-K test,sliding T test,cumulative anomaly and Morlet wavelet transform.Meanwhile,change characteristics of the days and intensity about erosive rainfall and precipitation were studied. [Results]Mean annual precipitation in the Malian River Basin was 482 mm and precipitation in four seasons respectively accounted for 18%,53%,27%,and 2% of the annual precipitation,erosiv