Implementation of a Hydraulic Routing Model for Dendritic Networks with Offline Coupling to a Distributed Hydrological Model

Abstract

The authors present a new set of tools for solving the one-dimensional Saint-Venant equations (1D-SVEs) of flow transport throughout dendritic river networks. The numerical solver is integrated with a set of geoprocessing tools, which include automatic cross-section selection, river bathymetry extraction, and a selection of model parameters, that facilitate the implementation of the 1D-SVE simulation setup. In addition, geographic information systems (GIS)–based preprocessing tools are developed to provide a seamless coupling of the hydraulic model to a hydrological model, which provides estimates of surface and subsurface runoff from hill slopes and performs routing in river networks using simplified ordinary differential equations. The hill slope runoff and streamflow generated by CUENCAS are redistributed as lateral inflows to the channels modeled by the 1D-SVE hydraulic model. The coupling of the hydraulic and hydrologic (H-H) models enables the validation of the hydrological model at internal locations in the basin where stage measurements are made, instead of only at locations where streamflow is estimated. An application of the coupled H-H models is demonstrated in the Squaw Creek watershed, Iowa. Results show that the coupled H-H models serve to validate assumptions in the hydrological model related to the spatial and temporal production of runoff in the watershed and bolster confidence in the estimated discharges at ungauged locations.