River Channel Geometry and Rating Curve Estimation Using Height above the Nearest Drainage

Abstract

River channel geometry is an important input to hydraulic and hydrologic models. Traditional approaches to quantify river geometry have involved surveyed river cross sections, which cannot be extended to ungaged basins. In this paper, we describe a method for developing a synthetic rating curve to relate flow to water level in a stream reach based on reach‐averaged channel geometry properties developed using the Height above Nearest Drainage (HAND) method. HAND uses a digital elevation model (DEM) of the terrain and computes the elevation difference between each land surface cell and the stream bed cell to which it drains. Taking increments in water level in the stream, HAND defines the inundation zone and a water depth grid within this zone, and the channel characteristics are defined from this water depth grid. We apply our method to the Blanco River (Texas) and the Tar River (North Carolina) using 10‐m terrain data from the United States Geological Survey (USGS) 3D Elevation Program (3DEP) dataset. We evaluate the method's performance by comparing the reach‐average stage‐river geometry relationships and rating curves to those from calibrated Hydrologic Engineering Center's River Analysis System (HEC‐RAS) models and USGS gage observations. The results demonstrate that after some adjustment, the river geometry information and rating curves derived from HAND using national‐coverage datasets are comparable to those obtained from hydraulic models or gage measurements. We evaluate the inundation extent and show our approach is able to capture the majority of the Federal Emergency Management Agency (FEMA) 100‐year floodplain.

A Hydraulic MultiModel Ensemble Framework for Visualizing Flood Inundation Uncertainty

“…It is possible that future work can use terrain‐based models such as Height Above Nearest Drainage, which could be a reasonable substitute for the computationally intensive hydraulic models (Zheng et al. ). However, in areas with highly dynamic flow conditions, such as in tidal river reaches, the proposed framework offers a viable approach.…”

A CyberGIS Integration and Computation Framework for High‐Resolution Continental‐Scale Flood Inundation Mapping

“…As well‐known models such as those based on cross sections show poor scalability to continental scale (Zheng ), our companion paper (Zheng et al. ) proposes a CFIM methodology which estimates channel geometry properties and rating curves from high‐resolution terrain data. In the companion paper, scientific challenges of CFIM are discussed.…”

Featured Collection Introduction: National Water Model

“…The paper by Zheng et al. () addresses a key challenge in this approach, converting NWM water discharge predictions into water depth (flow stage) data in each of the NWM's 2.7 million stream reaches. They proposed and tested a methodology for deriving channel geometry and synthetic rating curves from the 10‐m HAND dataset for each stream reach.…”

“…Since such information is not available for the vast majority of the NWM stream reaches, the approach proposed by Zheng et al. () provides an alternative that enables the coupling of NWM predictions and HAND inundation estimates.…”