汉江流域土地利用/覆被变化的水文效应模拟研究

针对流域LUCC驱动因子众多、驱动因子与土地利用/覆被变化之间存在复杂的非线性动态关系的特点，以汉江上游流域LUCC模拟为例，构建基于人工神经网络（ANN）与元胞自动机（CA）的模拟土地利用/覆被变化的CA ANN耦合模型，并应用该模型预测汉江上游流域2020s年代的LUCC变化情景。结果表明：2020s汉江黄家港站上游流域水田、旱地、灌木林与建设用地面积均有不同程度的增加，其中建设用地增幅最大，与区域交通和城市化的迅猛发展趋势相符；除建设用地增幅变化较大之外，1980s～2000s与2000s～2020s两个时期其余土地利用/覆盖类型的面积变化率都比较相近，表明CA ANN耦合模型能够刻画土地利用/覆盖类型的转换规律，在流域土地利用/覆被变化的复杂非线性动态演变情景的模拟预测方面是可行的。在此基础上，应用SWAT分布式水文模型模拟汉江上游流域水文过程。研究结果表明：在1980s年代、2000s年代及预测的2020s年代LUCC情景下，汉江上游流域年平均径流量呈增加趋势，LUCC对径流量年内影响较汛期显著，多年平均蒸散发量呈增加趋势

SIMULATION OF HYDROLOGICAL RESPONSE TO LAND USE/COVER CHANGE IN HANJIANG BASIN

Land Use/Cover Change (LUCC) and its hydrological impacts on watershed are the highlighted research issue on the global change, and delving into and quantifying the hydrological effects caused by land use/cover change contribute to an overall assessment of the hydrological cycle and water resources evolution within the watershed. The forcing factors that drive LUCC in watershed are so numerous and the nonlinear relationships between the factors and LUCC are so complicated that it is very difficult to build a simulation model. Intelligent modeling with the capability of nonlinearity and self adaption provided an efficient route for the simulation of the dynamic evolution of complicated system. In this paper, a coupled CA ANN model based on Cellular Automata (CA) and Artificial Neutral Network (ANN) was established for the simulation of LUCC in watershed. The upstream watershed of Hanjiang basin was taken as the case study, with land use in 1980 and 2000 as calibration and validation, respectively, and the transferring area and probability of LUCC were analyzed. The CA ANN coupled model was built for the simulation of the transition rules and dynamic evolution of LUCC and the satisfied accuracy in LUCC simulation was obtained. The scenario of land use/cover in 2020s was simulated by using the established CA ANN coupled model. The results showed that the paddy field, dry farm, shrubbery and construction land area in 2020 would increase in varying degrees. The woodland, grassland and water body area would decrease. The simulated results corresponded to the trends of LUCC in the upstream watershed of Hanjiang basin, which demonstrated that the coupled CA ANN model could simulate the complicated nonlinear dynamic evolving process of LUCC land use/cover change in watershed. On this basis, this study applied the distributed hydrological model (SWAT model) to simulate the hydrological processes in the upstream watershed of the Hanjiang Basin, and analyzed the variation of surface runoff and evapotranspiration in watershed under different LUCC scenarios. The results indicated that the annual average runoff tended to increase and the annual LUCC had more significant impact on runoff than the flood season, average annual evapotranspiration of years showed a upward trend under the LUCC scenarios of 1980s, 2000s and the simulated 2020s