用直接估算法确定区域潜水蒸发量

藉助于遥感图片与ＧＩＳ技术以及灌区内的潜水蒸发试验场试验结果，直接估算叶尔羌河灌区区域性潜水蒸发量。用遥感图所示确定土地利用类型，用ＧＩＳ技术对不同土地类型与不同地下水等埋深区面积进行统计，用试验场内不同土质不同潜水埋深的潜水蒸发观测资料（概括成经验公式）按不同土地类型计算潜水蒸发量，其中有植被的土地的潜水蒸发用降低蒸发面法处理。用本方法计算得潜水蒸发量结果与用水均衡法估算结果相近

Direct Estimation Method to Determine Regional Phreatic Evaporation

The regional phreatic evaporation has been estimated in Yerqiang River irrigation district based on the Remote Sensing imagines, Geographical Information System(GIS), and results of lysimeters. The land use types are determined by using Remote Sensing imagines.The statistic of the different land use and different groundwater table is completed by using GIS. Phreatic evaporation for different land use is calculated by empirical formula which come from the measured data of groundwater evaporation for different soil and different groundwater table. The groundwater evaporation from vegetated land is calculated by lowered evaporation surface method. That the calculated results of phreatic evaporation by above method agree well with the results by water balance method.