梅溪流域城镇化进程对山前平原区洪涝过程的影响

Impact of urbanization in the Meixi River Basin on flood process in piedmont plain area

为探究城镇化进程引起土地利用类型变化对山前平原区洪涝过程的影响,以梅溪流域下游平原区的洪濑镇为例,分析了2002—2018年梅溪流域上游山区和下游平原区的土地利用类型变化,并基于多情景数值模拟,研究了流域尺度内土地利用类型变化对山前平原区洪涝过程和地表淹没状况的影响。结果表明:随着梅溪流域耕地和林地面积减少、城镇建设用地增加,上游山区的径流系数和峰值流量均增大,下游山前平原区的淹没状况更加严重;上游山区的城镇建设用地增加使山区骤发洪水峰值流量增大、峰现时间提前,主要影响地表平均最大淹没水深和平均峰现时间;下游平原区的城镇建设用地增加使内涝发生的时间提前,主要影响地表平均淹没历时。

To investigate the impact of land use type changes caused by urbanization on the flood process in the piedmont plain area,the Meixi River Basin and Honglai Town in its downstream plain area was selected as the research area.The land use type changes in the upstream mountainous area and downstream plain area of the Meixi River Basin from 2002 to 2018 were analyzed.Based on multi scenario numerical simulation,this study investigates the impact of land use type changes on flood processes and surface inundation in the piedmont plain area at the watershed scale.The results show that with the reduction of arable land and forest land and the increase of urban construction land in the Meixi River Basin,the runoff coefficient and peak flow in the upstream mountainous areas both increase,and the inundation situation in the downstream piedmont plain area becomes more severe.The increase of urban construction land in upstream mountainous areas has increased the peak flow of sudden floods in mountainous areas and advanced the peak time,mainly affecting the average maximum submergence depth on the surface and average peak time.The increase of urban construction land in the downstream plain area has advanced the occurrence of waterlogging,mainly affecting the average duration of surface inundation.