基于DEM的河宽模型在山区中小流域内的构建与应用

Construction and Application of DEM-based Channel Width Model in Mountainous Medium-small Watersheds

合理可靠地估算河道栅格单元内的河道断面宽度是分布式水文模型汇流计算时的重点和难点问题。为此,研究提出一种适用于山区中小流域的河宽模型。该模型综合考虑了集水面积和地形对河流宽度的影响,利用DEM数据提取了河道上游集水面积和河道附近一定范围内的坡度,并建立起与河道断面宽度之间的函数关系,进而构建适用于不同流域的河宽模型。结果表明,在未明显受到水利工程影响的河段上,可以较为准确地估算出河道宽度的空间分布,刻画出自然条件下河道宽度从上游到下游震荡增大的变化特点;且基于不同分辨率的DEM数据构建的河宽模型均能取得较好的计算结果。

It is an important and difficult problem to estimate river section width of river grid unit reasonably and reliably in the flood routing calculation of distributed hydrological model.To this end,an improved river width model,which integrates the influences of rain collection area and topography on river width changes,is proposed for estimating the width of rivers in mountainous medium-small watersheds.The digital elevation model (DEM) is utilized in the model to derive upstream confluence area and land s slope,and the function relationship between these factors and river width is established to construct a river width model suitable for different watersheds.The application of model indicates that,(a) the spatial distribution of river channel width can be estimated more accurately on the river sections being not obviously affected by water conservancy projects,and the oscillation variation of river channel width from upstream to downstream under natural conditions can be characterized;and (b) all of developed river width models based on DEM data with different resolutions can achieve better calculation results.