基于GIS的三峡库区生态环境综合评价——Ⅳ.降水量变化（1951-2004）

根据三峡库区及周边地区1951-2004年33个气象站点的地面气象数据和1∶25万的地形图,利用线性趋势模型和＂回归分析＋残差修正＂插值法生成库区100m×100m的气候变化的时空分布图,定量评估三峡库区近54a来降水量的年和季节变化规律。结果表明：1951年以来,库区年和四季降水量变化趋势不显著（p〉0.05）。年降水量在50年代-80年代后期有增多趋势,随后年降水量有减少趋势,90年代后期以后降水变化幅度较大。在四季降水量的时间变化中,夏季降水量变化幅度较大,偏差一般在±80mm内;冬季降水量的变化幅度较小,偏差一般小于±10mm。50年代-70年代中后期-2004年,三峡库区春季经历了变湿-变干-变湿的过程;夏季正好相反,经历了变干-变湿-变干的过程;秋季气候在70年代中期前变湿,70年代中期后变干。同时,三峡库区的降水量变化也存在区域差异：春季的东部地区（-4- -2mm/10a）和秋季的西南部（-6.3- -4mm/10a）、中部地区（-4- -2mm/10a）减少最显著;而夏季降水量呈增加趋势,虽然冬季大部分地区降水量也有增加,但增加幅度不大。

Integrated Assessment of Eco-environment in Three Gorges Reservoir Areas Based on GIS and DEM Ⅳ. Assessment of Precipitation Changes (1951-2004)

Based on the meteorological data of the annual precipitation in 33 meteorological stations in 1951 -2004 and relief map, the characteristics of climate change in the Three Gorges Reservoir in recent 50 years was studied, by using the method of linear-trend estimate and "multiple regression model + Inverse Distance Weighting (IDW) residuals". The seasonal and annual precipitation changes were analyzed. The results indicated that the trend of annual and seasonal changes of precipitation in the Three Gorges Reservoir areas was not significant (p >0. 05) since 1951. The mean annual precipitation had a increasing trend from the 1950's to 1980's, while it had a decrease trend subsequently. The change range of precipitation became larger since late 1990's. For the seasonal changes of precipitation, the change range of precipitation in summer was large, and the positive and negative deviations was generally within 80mm, whereas the change range of precipitation in winter was small, and the positive and negative deviations was generally less than 10mm. In the three period of 1950's to mid-late 1970's, mid-late 1970's to mid-late 1980's and after 1980's, the Three Gorges reservoir area experienced drier wetter and drier process in the spring, while on the contrary, in summer it experienced wetter, drier and wetter process. Before the mid 1970's, climate in autumn became wetter, while it became drier after the mid 1970's. At the same time, the change of precipitation in the reservoir areas had regional differences. The precipitation in the east areas decreased 2 -4mm per decade in the spring, while it decreased 4-6. 3 mm per decade in the southwest areas in the autumn. The precipitation in the central areas decreased 2 -4 mm per decade in autumn. In summer, the precipitation had an increased trend, while in winter the precipitation also had an increased trend, but the trend was not very obvious.