Fluvial Geomorphic Analyses of the Llano River and Sandy Creek Basins, Central Texas, using GIS and Arc Hydro Tools Franklin T. Heitmuller CE 394K November 29, 2005

Study Area

Flood Regime

Objectives 1. Obtain digital elevation models (DEMs) of the study area 2. Obtain 1:24,000 NHD hydrography for study area 3. Use Arc Hydro Tools to generate GIS datasets for study area 4. Generate longitudinal profiles (plot of elevation and distance downstream) of selected rivers/streams in study area 5. Assess the potential of modeling stream power in study area

Digital Elevation Models  30-meter and 10-meter   Problems with 10-meter in study area; vertical stripes of no data; obtained from contact at USGS in Austin  30-meter mosaic: 110 mb/2 panels  10-meter mosaic: 1.81 gb/12 panels

National Hydrography Dataset

Arc Hydro Datasets

Longitudinal Profiles Export of selected features from 1:24,000 NHD hydrography data (1) Need distance downstream. (2) Need elevation data.

Longitudinal Profiles

Allows point features to be created along a line at a user-specified interval (100 meters)

Longitudinal Profiles

Stream Power Modeling   τ0 = ρgdS,   where τ0 is boundary shear stress in newtons per square meter, ρ is density of water in kilograms per cubic meter, g is the acceleration of gravity in meters per second squared, d is average flow depth in meters, and S is channel slope.   ω = Uτ0,   where ω is stream power per unit bed area in watts per square meter and U is average flow velocity in meters per second. Can stream power be modeled using GIS?

Stream Power Modeling  Start off with channel slope……

Stream Power Modeling

North Llano River near Junction, Texas