流域土地覆被变化水文效应的模拟——以长江上游源头区梭磨河为例

为分析地表覆被变化的水文效应，以半分布式的地形指数模型 (TOPOMODEL) 为基础，对梭磨河流域1960~1999年逐日流量过程进行了模拟。结果表明，对于流域面积2536km² 的梭磨河流域，该模型也能取得较好的模拟结果。模拟了流域40年来气候波动和地表覆被变化对流域水文的影响。最后在4种不同的流域土地覆被情景下模拟了1960~1999年逐日径流过程。对于实际蒸散发与潜在蒸发有300多mm差距的梭磨河流域，在其它条件不变的情况下，随着流域土地覆被和冠层最大截流量的增加，冠层截流蒸发和流域总蒸发增加，植被蒸腾和土壤表面蒸发减少，土壤水分增加而流域水分含量和饱和层含水量减少。地表径流、地表以下径流、总径流减小。重现期小于20年的洪峰流量减小，但对40年一遇的洪峰流量影响很小，甚至有增加洪峰流量的作用。

Simulation of Hydrological Response to Land Cover Changes in the Suomo Basin

In order to study the effects of land cover changes on hydrology, t he TOPMODEL was tested for the Suomo basin on the upper reaches of the Yangtze River. A modified version of the model was used to adapt to the basin condition and data availability. The model was calibrat ed with five year measured daily discharge record (1980-1984) and the parameters were estimated. With this model and the maps of land cover of the 1970s, the 1980s and the 1990s, daily discharge from 1960 to 1999 was simulated. Comparing simulated discharge with the measured records from 1 960 to 1999 in percentage efficiency, the model gave a sound result. After that, simulation was conducted under four land cover scenarios w ith the tested model. The main results were as follows: With the increase in lan d cover and interception capability, the basin interception evaporation i ncreased, transpiration and soil evaporation decreased, and overall evap oration increased. Soil moisture increased and saturation zone storage and basin water storage decreased with the increase in land cover and maximum int erception capability. Surface runoff and stream discharge decreased and subsurface runoff increased with the increase in land cover at the b eginning while decreased with further land cover increase. The degree of hydrological effects of land cover increase depends on the differen ce value between actual evapotranspiration and potential evaporation.The bigger difference, the higher effects of land cover changes on basin hydrology a re.