基于地下水陆面过程耦合模型的黑河干流中游耗水分析

耗水分析能够直接揭示水资源利用的本质,蒸散发是流域尺度耗水的主体.将一个典型的陆面过程模型和一个地下水模型紧密耦合,从而在地下水模型中增加具有物理机理的蒸散发描述,同时改进陆面过程模型中地下水的动力过程,由此在发挥这两类模型各自优势的基础上,构建了一个地下水-陆面过程耦合模型.利用该模型模拟了黑河干流中游2008年逐小时的蒸散发过程.结果表明:黑河干流中游2008年总耗水量约为35.7×108 m3,耗水最大的地表类型是农作物为19.3×108 m3、裸地和戈壁为7.2×108 m3、草地为6.0×108 m3、稀疏植被为3.1×108 m3,其中,不同地表类型的年蒸腾量分别为8.8×108 m3、0.02×108 m3、2.2×108 m3以及0.4×108 m3,对应它们的年蒸散发强度分别为:580mm、117mm、331mm以及202mm.通过耗水平衡分析也得到2008年黑河干流中游地下水呈负平衡状态,全年地下水超采约0.9×108 m3,其中区内地下水储量在7—11月间呈增加趋势,其他各月呈减少趋势.

Analyzing Water Consumption in Middle Reaches of Heihe River Based on Groundwater-Land Surface Coupling Model

Water consumption analysis can directly reveal the essence of water use.In the basin scale,the evapotranspiration is the main body of water consumption.In this paper,a typical land surface model is coupled with a groundwater mode base on their respective advantages,and a groundwater-land surface model is developed.In the coupling model,the evapotranspiration process of groundwater model is described base on the physical mechanism,and the subsurface water movement of the land surface model is improved.The coupling model is then applied to the hourly evapotranspiration simulation in the middle reaches of the river in 2008.The results show that the total water consumption in the middle reaches of the river is about 35.7×108 m3 in 2008,and most of water consumption is from croplands(19.3×108 m3),bare land and gobi(7.2×108 m3),grassland(6.0×108 m3) and sparse vegetation(3.1×108 m3),respectively.Correspondingly,the annual evapotranspiration is 8.8×108 m3,0.02×108 m3,2.2×108 m3 and 0.4×108 m3,respectively,from the four land surfaces,and the annual intensity of evapotranspiration is 580 mm,117 mm,331 mm and 202 mm,respectively,from them.In addition,the groundwater in the middle reaches of the river showed a negative balance,with an overexploited amount of about 0.9×108 m3,in 2008 base on the water balance analysis.It is also found that groundwater increases from July to November and decreases in other months.