干热河谷区降水量的变化特征研究--白鹤滩水电站为例

The Variations of Rainfall in Dry-hot Valley:A Case Study of Baihetan Hydropower Station

位于干热河谷区的白鹤滩水电站是全球第二大水电站,掌握水电站及周边降水量的时空变化,有利于提高水电生产的效率,同时降低自然灾害的风险。采用水电站自建气象站的降水观测数据,分析坝区降水量的季节、年际和日变化特征,并与周边地区进行了对比分析,研究了干热河谷区降水变化的特殊性。研究表明:水电站河谷具有显著的干湿季分明和雨季集中,以及雨日少和降水量少的“干”热特点;河谷区主雨季偏早,干湿季转换明显,且具有伏旱季和秋绵雨,以及降水集中度明显偏高的特征;白鹤滩河谷降水日变化表现为夜雨频繁的单峰单谷型,降水倾向于集中发生在04∶00~05∶00;河谷降水年际差异大,旱涝不均和旱涝急转现象时发;河谷区强降水事件发生频率低,且具有夜发性和局地性强,以及强降水在雨季随机分布的特征。

Baihetan Hydropower Station,located in the dry-hot valley,is the second largest hydropower station in the world.Mastering the multi-temporal scale changes of rainfalls in hydropower station area and surrounding areas can improve the effectiveness of hydropower production and reduce the loss of natural disasters.Based on the precipitation data from the self-built monitoring stations of Baihetan Hydropower Station,the seasonal,inter-annual and diurnal variation characteristics of precipitation in dam area are analyzed,and compared with that in surrounding areas to study the particularity of precipitation variation in dry-hot valley area.The study shows that:(a)the river valley of hydropower station has obvious dry-hot characteristics of distinct wet and dry season and concentrated rainy season,and fewer rain days and less precipitation;(b)the main rainy season is earlier in the valley,the change of dry and wet seasons is obvious,and moreover,the valley has the characteristics of dry Dog days and rain autumn,and obvious higher precipitation concentration;(c)the diurnal variation of precipitation in Baihetan valley is characterized by a single peak,frequently at night from 04∶00 AM to 05∶00 AM;(d)the precipitation in the valley varies greatly from year to year,and the phenomenon of uneven drought and flood and rapid shift from drought and flood is frequently occurred;and(e)the occurrence frequency of heavy precipitation events in the valley is low,and the heavy precipitation usually occur in night and in local,and are randomly distributed in rainy season.