中文摘要：

对浙江省义乌市降水的长期变化趋势和特征进行了分析。指出一条解决该市缺水的有效途径是利用雨季有利的降水天气条件，通过人工增雨作业，将水库蓄满，以备旱季使用。为了在既保证水库蓄满水量、又不致产生暴雨洪水灾害条件下实施人工增雨作业，提出了水库实时蓄水标准的新概念。在水库实时蓄水标准的具体实施过程中，可根据义乌市降水的长期变化趋势和特征，结合中期和短期的天气预报，判断是否需要对近期的天气条件实施人工增雨作业。

英文摘要：

By references to historical records from Jinghua and Yiwu, with the precipitation data from May to September during the period of 1980 -2006, the long-term change tendency and characteristics of precipitation in Yiwu are analyzed. The results show that ： （ 1 ） Yiwu City will be mainly on a long period of drought years in the future. （2） In the year or next when El Nino phenomenon occurred, the precipitation increased evidently in Yiwu Station, and the end of Plum Rain days was later than other years; but in the year or next when La Nina phenomenon occurred, the precipitation decreased evidently in the station, and the end of Plum Rain days was earlier. At present, with the rapid economic development in Yiwu, the water shortage is being a serious problem. So, an effective approach is to use favorable weather condition to carry out artificial rainfall in rainy season, making reservoirs impound so as to prepare against drought in dry seasons. In order to avoid bringing the possible flood in the process of artificial rainfall, a new concept of real-time water storage standard of the reservoirs is put forward, namely the rates of accumulative value of monthly precipitation in the first half-year with total precipitation in the first half-year are taken as controlling standard for the reservoirs storing water. It is of significance for Yiwu to fully use favorable weather conditions in plum rain season to carry out artificial precipitation in time for resolving the contradiction between supply and demand of water in drought summer season.