1960-2008年黑河流域地表干湿状况的时空变化分析

利用1960-2008年黑河流域16个气象站的逐日气象资料，采用FAO推荐的Penman-Monteith公式计算最大可能蒸散量，进而计算该流域的湿润指数，对地表干湿状况的时空变化特征及其主要影响因素进行分析。结果表明：黑河流域及其上、中、下游地区的湿润指数总体呈上升趋势，地表湿润状况有所改善，且湿润指数的年际波动性较明显，变异系数分别为14.97%、13.63%、25.47%、37.72%。除下游地区外，夏季的湿润指数变化速率最快，冬季的变化速率最慢；春季，黑河流域地表以变干趋势为主，其他季节均以变湿趋势为主。影响黑河流域地表干湿状况的主要因素是降水量，其他气候因子的变化对地表干湿状况起增强或削弱作用。

Analysis on Spatiotemporal Change of Dry-wet Conditions in the Heihe River Basin during the Period from 1960 to 2008

In recent 50 years,a significant climate warming has occurred in China under global climate change,and it has facilitated the development of drought.Climatic dry-wet conditions have attracted more and more attention in recent years.The change of dry-wet conditions will cause the far-reaching impacts to prospective agricultural production and natural environment,especially in northwest China.Located in the arid and semiarid areas in northwest China,the Heihe River Basin is the second largest inland river basin in China.Water resources have become as a "bottleneck" of social and economic development and ecological regeneration in the Heihe River Basin.Investigation on the temporal and spatial distribution of water resources in this region would be greatly helpful for the utilization efficiency improvement,appropriate redistribution of water resources,and relieving environmental deterioration.Based on the daily meteorological data observed by 16 meteorological stations in the Heihe River Basin during the period from 1960 to 2008,in this study the values of daily evapotranspiration of reference crop were calculated using the Penman-Monteith method recommended by the FAO,and then the values of monthly,seasonal and annual evapotranspiration of reference crop were obtained.In order to study the temporal and spatial change of dry-wet conditions in the study area,the humid index values at different time were interpolated using the data of evapotranspiration of reference crop and precipitation.By using the method of Inverse Distance Weighted(IDW) under ArcGIS,the spatial change of the dry-wet conditions was lucubrated so as to research the regional difference.In this study,a preliminary analysis on the main factors affecting the change of the dry-wet conditions was also carried out.The results indicated that the values of mean annual humid index were generally in an increase trend in a fluctuation way in the Heihe River Basin and its upper,middle,lower reaches in recent 49 years,and the surface humid status was improved to some extent.It was also found that the fluctuation of annual humid index was obvious,and the Cv(coefficient of variation) values of humid index in the Heihe River Basin and its upper,middle,lower reaches were 14.97%,13.63%,25.47% and 37.72% respectively.Seasonally,the drying trend occurred in spring,and the wetting trend occurred in summer,autumn and winter.According to the humid index,summer was the wettest season,then autumn and spring,and winter was the driest season.Apart from the lower reaches,the variation rate of summer humid index was the fastest,so the change of the dry-wet conditions was the most unstable in summer,and it was the most stable in winter.Correlation analysis between humid index and meteorological variables indicated that the change of precipitation was the dominant cause affecting the change of dry-wet conditions in the Heihe River Basin,and the change of other climate factors can enhance or weaken the change of dry-wet conditions.