基于DEM的地貌单位线在汉江上游洪水预报中的应用

Application of geomorphologic unit hydrograph based on DEM in flood forecast in upstream of Hanjiang Basin

汉江上游部分中小河流由于缺少长期实测水文资料,难以利用传统的单位线进行汇流计算。因此,提出一种基于DEM的地貌单位线方法,该方法以30 m×30 m分辨率的DEM为原始数据,采用ARCGIS提取流域水系及地貌特征参数,推导地貌单位线,进而构建流域汇流模型。以汉江上游鄂坪水库为例,挑选2020年和2021年汛期4场较为典型的洪水过程,对该流域“蓄满产流+地貌单位线”预报模型模拟效果进行验证。结果表明:基于DEM的地貌单位线在鄂坪水电站入库洪水预报中效果较好,可在汛期为水库防洪调度提供依据,同时可为汉江上游缺资料中小河流的洪水预报汇流计算提供参考。

In view of the lack of long-term measured hydrological data for some small and medium-sized basins in the upstream of Hanjiang basin,the traditional unit hydrograph can not be calibrated for runoff concentration calculation.Using DEM with a resolution of 30 m×30 m as the original data,ARCGIS was used to extract the river system and geomorphic characteristic parameters of the basin,deduced the geomorphic instantaneous unit Hydrograph,and constructed the basin concentration model.Taking Eping Reservoir in the upstream of Hanjiang Basin as an example,four typical flood processes in the flood season of 2020 and 2021 were selected to verify the simulation effect of the Forecast model of"saturation excess runoff and geomorphic unit hydrograph"in the basin.The results showed that the geomorphic unit Hydrograph based on DEM had a good effect on flood forecast of Eping Hydropower Station,which can provide decision-making basis for reservoir flood control operation in flood season,and provide a new idea for flood forecast of small and medium-sized rivers lacking data in the upstream of Hanjiang Basin.