A new multiscale flow network generation scheme for land surface models

Abstract

This paper presents a new multiscale approach for generating flow networks for land surface models that are applied at different spatial scales. This new approach has the following advantages: (1) it allows runoff in a land surface model grid to exit by multiple directions simultaneously, rather than be limited to one of the eight directions as in many other methods; and (2) it introduces a scaling factor, the tortuosity coefficient, to determine hydrologic parameters for more accurate flow routing across different spatial scales. The new flow network generation scheme has been applied, in conjunction with a kinematic wave routing method, to the Blue River basin in Oklahoma at different spatial resolutions. Comparison of the routed streamflows shows clear advantages of the new approach over the widely used eight directions (D8) method, especially at coarser resolutions. 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.