土地利用变化对流域水文过程时空分异的影响 ——以赣江流域为例

土地利用变化引起的水文分量时空变化对认识流域产汇流过程，优化流域土地利用结构和水资源规划具有重要意义。基于SWAT模型，本研究以赣江流域为例，结合1980、2000、2015年3期土地利用数据从水文响应单元的角度，系统分析了单纯土地利用变化对流域产流、蒸发、入渗以及径流等主要水文过程时空分布的影响。结果表明：1980~2015年间，流域内的土地利用变化主要表现为耕地和林地的减少，城乡建设用地的增加；林地的减少和城乡建设用地的增加是产流增加，蒸发和入渗减少的主要原因；总体上，土地利用变化对局部地区水文过程影响较大，但因土地利用类型之间的相互转化和其影响的叠加，流域尺度上的综合水文效应明显降低；土地利用变化导致整个赣江流域平均径流量增加了2.33×108m3，相比较近年来赣江径流的减小幅度其影响十分有限。近年来，赣江入湖径流量的下降主要是由气候变化和其他人类活动作用特别是流域工农业用水的大幅增长所致。流域水文过程模拟应充分考虑土地利用变化水文效应的时空分异，注重天然和社会水循环的耦合，才能更为真实的反映流域水文过程，更好的为流域土地利用结构优化和水资源的高效管理提供科学依据。

Impact of Land Use Change on Spatio-temporal Differentiation of Watershed Hydrological Processes: A Case Study of Ganjiang River Basin

The spatio-temparal variations of hydrological components caused by land use change is of great significance for understanding of runoff generation process, and optimizing land use structure and water resources planning. Based on three scenarios of land use data in 1980, 2000 and 2015 this study systematically investigates the impacts of land use change on the spatial-temporal variations of major hydrological processes such as runoff generation, evaporation, infiltration and runoff from perspective of hydrological response unit, by applying the SWAT model in Ganjiang River Basin as an example. Results show that land use change of the basin during 1980-2015 was mainly reflected by the reduction of cultivated land and forest land as well as the increase of urban and rural construction land. The reduction of forest land and increase construction land mainly contributes to the increase of runoff generation and the decrease of evaporation and infiltration. Generally, land use change has a greater impact on local hydrological processes, while the integrated hydrological effects are significantly reduced at watershed scale due to the mutual transformation of land use types and their overlapping effects, . The modelling result revealed that the effect of land use change has caused to an increase of average annual runoff of by 2.33×108m3 in the Ginjiang River Basin, which is quite small with reference to the observed runoff reduction in recent years. On this basis, the runoff decrease of Ganjiang River was mainly affected by climate change and other human activities, especially dramatic increase of water utilization for industry and agriculture in the basin. It is concluded that hydrological modelling should fully consider the spatio-temporal variations of hydrological effects of land use change, and pay attention to the coupling of natural and social water cycles, only in this way can watershed hydrological processes be more truly reflected and the scientific basis for the optimization of land use structure and the efficient management of water resources in the river basin be better provided.