Global-scale river routing—an efficient time-delay algorithm based on HydroSHEDS high-resolution hydrography

摘要

Coupling of global hydrologic and atmospheric models is difficult because of the highly nonlinear hydrological processesnto be integrated at large scales. Aggregation of high-resolution data into low-resolution spatial distribution functions is onenway to preserve information and account for the nonlinearity. We used HydroSHEDS, presently the most highly resolvedn(300n) global hydrography available, to provide accurate control on global river routing through a computationally efficientnalgorithm. The high resolution of HydroSHEDS allowed discrimination of river-channel pixels, and time-delay distributionsnwere calculated for all such pixels. The distributions were aggregated into network-response functions (NRFs) for each low-nresolution cell using an algorithm originally developed for the 1-km-resolution HYDRO1k hydrography. The large size ofnHydroSHEDS required a modification in algorithm to maintain computational efficiency. The new algorithm was tested withna high-quality local and a more uncertain global weather dataset to identify whether improved routing would provide a gainnwhen weather data quality was limiting. The routing was coupled to the WASMOD-M runoff-generation model to evaluatendischarge from the Dongjiang River and the Willamette River basins. The HydroSHEDS-based routing, compared with thenHYDRO1k-based routing, provided a small gain in model efficiency, for local and global weather data and for both test basins.nThe HydroSHEDS-based routing, contrary to the HYDRO1k-based routing, provided physically realistic wave velocities. Thenmost stable runoff-generation parameter values were achieved when HydroSHEDS was used to derive the NRFs. Routingnwas computed in two steps: first, a preparatory calculation which was a one-time effort and second, the routing during eachnsimulation. The computational efficiency was four to five orders of magnitude better for the simulation step than that for thenpreparatory step. Copyright  2010 John Wiley & Sons, Ltd.