SWAT模型在土地利用/覆被变化剧烈地区的改进与应用

人口增长、气候变化、制度变迁、城市化等均会导致土地利用/覆被的变化,进而引起流域水文过程（截留、入渗、蒸散发和地下水补给等）和水循环过程的改变。当前,由于逐年土地利用/覆被数据获取困难、水文模型本身计算缺陷等问题,所有在流域尺度上开展的借助水文模型进行的土地利用/覆被变化影响下的水文模拟研究都存在一个共同缺点,就是采用的水文模型并不能逐年调用土地利用/覆被数据,即水文模型无法真实体现或模拟土地利用/覆被的时空变化。SWAT作为一个广泛应用的分布式水文模型,在其模拟期内,不能逐年调用土地利用/覆被数据,即在进行水文模拟时忽略了土地利用/覆被时间上的变化,这可能会影响其在土地利用/覆被变化剧烈地区（如黑河中游）的应用。黑河流域是典型的内陆河流域,也是中国西北地区第二大内陆河流域。黑河中游是黑河流域的径流耗散区。本文针对SWAT模型在考虑土地利用/覆被变化时的缺点,对其进行了改进并开发出能够逐年调用土地利用/覆被数据的LU-SWAT模型。在土地利用/覆被变化剧烈的黑河中游对SWAT和LU-SWAT模型的径流模拟效果进行比较,发现LU-SWAT模型更适用于黑河中游水循环模拟。

Improved SWAT and Its Application to a Region with Severe Land Use / Land Cover Changes

Population growth, climate change, institutional change and urbanization etc. would cause the change of land use / land cover, which in turn would further affect the hydrological process (e.g. infiltration, surface runoff, evapotranspiration and lateral flow) and water balance. Currently, because of the difficulties in obtaining the yearly land use / land cover data and the problems in calculating process in hydrological models, the simulation of hydrological process under the impact of land use / land cover change is conducted on one period each time and the impacts of multiple periods (e.g. multiple years) of land use / land cover change cannot be simulated continuously. That is the models could not call land use / land cover data year by year seamlessly. SWAT （Soil and Water Assessment Tools）is a distributed hydrological model. During its simulation period, it could not call land use / land cover data year by year and neglects the land use / land cover change in time scale. This would impact its applications in regions with severe land use / land cover changes (e.g. the Middle Reaches of the Heihe River). Heihe River Basin is the second largest and a typical endorheic river basin in China. The middle reach consumes a major portion of the water in the Heihe River. For the weakness of SWAT model, this research developed a model called LU-SWAT that could simulate the impacts of multiple years of land use / land cover change continuously. Furthermore, we applied SWAT and LU-SWAT to simulating streamflow in the Middle Reaches of the Heihe River, and compared their efficiency. The results showed that the LU-SWAT model, which could call land use / land cover data year by year is more suitable to simulate the streamflow in the Middle Reaches of the Heihe River.