Document Type

Article

Journal/Book Title/Conference

Journal of the American Water Resources Association

Volume

54

Issue

4

Publisher

Wiley

Publication Date

6-12-2018

First Page

1

Last Page

40

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 ungauged 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 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 (TX) and the Tar River (NC) using 10-meter terrain data from the USGS 3DEP Elevation dataset. We evaluate the method’s performance by comparing the reach-average stage-river geometry relationships and rating curves to those from calibrated 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 that our approach is able to capture the majority of the FEMA 100-year floodplain.

Available for download on Wednesday, June 12, 2019

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