泾河上游流域实际蒸散量及其各组分的估算

利用分布式生态水文模型SWIM，基于泾河上游(泾川测站以上) 植被、土壤、气象和水文数据对研究区进行了水文过程的模拟，从而估算了流域的实际蒸散量及其各组分。结果表明：SWIM模型能够较好的模拟泾河上游流域的水文过程，模拟的流域多年(1997-2003 年) 平均实际蒸散量为443 mm，其中土壤蒸发量为259 mm，植被蒸腾量为157 mm，冠层截持量为27 mm。石质山区的森林覆盖区和非森林地的年蒸散总量在整个流域分别具有最大值和最小值，为484 mm和418 mm；黄土区实际蒸散量介于二者之间，平均为447 mm。森林覆盖地区土壤蒸发明显小于其它区域，而蒸腾和冠层截留明显大于其它区域。年内蒸散量主要集中在5-8 月份，占全年总蒸散量的60%，且冠层蒸散比例较大达63%。整个流域湿润年份较干旱年份蒸散量增加了78 mm，其中土壤蒸发增加最多，其次是冠层蒸腾，冠层截留蒸发最小。

Estimation of Actual Evapotranspiration and Its Component in the Upstream of Jinghe Basin

The ecohydrological model SWIM was used to simulate the hydrological process based on the data of vegetation, soil, climate, hydrology in the upstream of Jinghe River located at the Jingchuan station, and actual evapotranspiration and its components were estimated. The result showed that SWIM model was applicable to this area, and the average annual actual evapotranspiration (AET) was 443 mm from 1997 to 2003 in the watershed, with soil evaporation being 259 mm, vegetation transpiration 157 mm, and canopy interception 27 mm. In the watershed, the AET of the forest and non-forest area in rocky mountain was 484 mm in maximum and 418 mm in minimum respectively. And the AET of loess area was 447 mm lower than that of forest area and higher than that of non-forest area in rocky mountain. In addition, soil evaporation in forest area was significantly low, while the transpiration and canopy interception in the area were obviously high in the watershed. The inter-annual AET mainly occurred in the period from May to August, which was 60% of the total annual AET, with the great proportion 63% of canopy evapotanspiration. The AET of wet year increased by 78 mm compared with that of dry year, among which, soil evaporation increased greatest, followed by transpiration and canopy interception.