This paper presents a new approach of generating flow networks for land surface models that are applied at different spatial scales based on fine-resolution digital elevation model (DEM). Without losing computational efficiency, the new multi-scale approach has the following advantages compared to existing methods: (1) it allows surface and subsurface runoff from a land surface model grid to exit through multiple directions simultaneously rather than through only one of the eight directions as in many other methods; (2) it guarantees that the newly generated river network is closer to the real river network; and (3) it introduces the concept of elastic coefficient to determine hydrological features such as river slope and length for more accurate flow routing across different spatial scales. The new flow network generation scheme has been applied to the Blue River watershed in Oklahoma at different spatial resolutions using a kinematic wave routing method. Comparisons of the routed streamflows at the watershed outlet associated with different spatial scales show clear advantages of the new approach over the widely used eight directions (D8) method, especially at the coarser spatial resolution. This method is particularly suitable for macroscale hydrologic models and climate models where the accuracy of river routing can be severely limited by the coarse spatial resolution.
Revised: January 16, 2009 |
Published: December 11, 2004