Dynamic Manning's Roughness Coefficients for Hydrological Model in Basin

Abstract:

Roughness coefficient (n) has a significant impact on routing in hydrological model. However, computation methods of dynamic roughness coefficients are few concerned in current research; few studies have come up with a spatial-temporal distribution of roughness coefficients in basin. A formula to calculate the n value was established based on the statistical analysis of observations in this study. And then we improved the routing model of a distributed hydrological model using the new formula of n. Roughness coefficient is not constant but changes dynamically with the changing of water depth and vegetation in improved hydrological model. The improved model was applied in the Yellow River basin. The results show the dynamic roughness coefficients can improve the streamflow simulation of hydrological model and especially has a big influence in the routing model on the slope. The dynamic spatial-temporal distribution of manning's roughness coefficients can be afforded as the model output in basin. It is possible to apply this method to afford a spatial-temporal profile of roughness coefficients to support the global routing in land surface model.