Modeling inundation of seasonally flooded wetlands at McCarran Ranch on Truckee River, USA

Abstract

Abstract. This paper among the first presents the application and validation of a hydrodynamic model (Adaptive Hydraulics model, AdH) of the McCarran ranch. We use the AdH model with topographic data by combining the DEM data from USGS seamless server and the ESRI tin data from United States Army Corps of Engineers (USACE) to predict floodplain inundation for a river reach of ~10 km located at lower Truckee River in Nevada state. We tested the mesh independence, sensitivity of input parameters and time steps, and then compared the modeling results to the existing gauged data (both the discharge and water stage heights). Results show that the accuracy of prediction from AdH model can decline slightly at higher discharge and water levels. The modeling results are much sensitive to the roughness coefficient of main channel, suggesting the model calibration should give priority to the main channel roughness. The simulation results suggest that large flood events could lead to a significantly higher proportion of total flow that routed through the floodplains. During peak discharge, a river channel constriction diverted as much as 65% of the river's 512.3 m3s−1 discharge into the floodplain. During the overbank flow, the transboundary flux ratio is about 5–45% of the total river discharge. Results also showed that both the relation of inundation area and volume between the discharge exhibit an apparent looped curve form.

Two-Dimensional Unsteady Flow Modeling of Flood Inundation in a Leveed Basin

“…Accurate and reliable models increase confidence in decisions regarding land use, water management and public safety. The use of such models for flood inundation has been well documented over the last 10 years (Chen et al 2014, Falter et al 2103, Hosseinipour et al 2012, Jung et al 2012, Dutta et al 2007, Hall et al 2005. As with all two-dimensional modeling applications, the ability to produce reliable results is in part dependent on the availability and accuracy of measured field data for calibration and validation, and geometric representation of actual bathymetry.…”