基于改进SWAT模型的土地利用变化对流域设计洪水的影响研究

The Effect of Land-use Change on the Basin Design Flood Based on Improved SWAT Model

城市化进程会改变城市下垫面条件,影响地区产汇流过程,增加城市面临洪涝灾害的风险。为分析深圳市石岩流域土地利用变化对流域设计洪水的影响,对石岩流域1988、2002、2010和2016年的遥感影像图进行解译,分析该流域的土地利用变化状况;建立石岩流域改进后小时步长的SWAT模型,模拟该流域不同时期的土地利用下的设计洪水过程,并分析其变化趋势。结果表明:该流域28年间林地草地占比减少29%,耕地占比减少11%,城镇用地占比增加37%;随着林地耕地的减少和城镇面积的增加,不同频率设计洪水的洪量及洪峰均有所增加,且峰现时间也有所提前,2002-2010年期间增长幅度最大,其洪峰平均增长205.6 m3/s,洪量平均增加634.2万m3。该流域设计洪水受流域的城市化影响较剧烈,需要复核下游地区的防洪能力,以有效应对可能发生的洪水过程。

The process of urbanization will change the underlying surface of the city,affect the process of regional rainfall-runoff and increase the risk of the city facing flooding. In order to investigate the impact of land use change on design floods in the Shiyan River Basin in Shenzhen City,we interpret the remote sensing image maps of Shiyan Basin in 1988,2002,2010 and 2016 and analyze the changes of land use in the basin for 28 years. The SWAT model improved hourly steps is built for Shiyan River Basin to simulate the impact of land use scenarios on design flood in different periods of the basin. The results show that the proportion of forestland and grassland decreases by 29%,the proportion of arable land decreases by 11% and that of urban land increases by 37% over the 28 years. With the reduction in cultivated land and the increase in urban area,the flood peak and flood volume of design floods with different frequencies have increased,and the peak time has also been advanced. The largest growth rate occured between 2002 and 2010,with an average increase of 205.6 m3/s in flood peak and 6 342 000 m3 in flood volume. In conclusion,the urbanization of the basin has a great impact on the design floods of the basin,so the flood control abilities of the downstream area need to be checked in order to effectively deal with the flood process that may occur.