Submitted to: Journal of the American Water Resources Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2002
Publication Date: 10/31/2002
Citation: ALLEN, P.M., ARNOLD, J.G., SKIPWITH, W. ERODIBILITY OF URBAN BEDROCK AND ALLUVIAL CHANNELS, NORTH TEXAS. JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION. 2002. v. 38(5). p. 1477-1492.
Interpretive Summary: Channel erosion and incision have both environmental and societal effects. These effects range from undermining bridges, undermining of pipeline crossings, and lowering local ground water tables, to loss of wildlife habitats and biodiversity. There are currently over 575,000 stream bank miles of erosion in the U.S. with cost of repair exceeding a billion dollars. In this study, we identified and quantified erosion processes and potential of different stream channel types in north Texas. Methods to quantify stream bank erosion rates were discussed and examined. This information is critical to city engineers and planners in targeting critical erosion areas and designing plans for stabilizing stream channel erosion.
Technical Abstract: Major erosion of urban stream channels is found in smaller basins in the North Texas study area with contributing drainage areas of less than ten square miles. Within these basins, four basic channel types are identified based on bed and bank lithologies: alluvial banks and bottoms, alluvial banks and gravel bottoms, alluvial banks with rock bottoms, and rock banks with rock bottoms. Most channels (75 percent) have alluvial banks with gravel or rock bottoms. Channel slopes are steep (.38 to .76 percent). Rock consists predominantly of shale and limestone. Channel cross sections are divided into the following four zones based on weathering, scour and entrainment mechanisms: soil zone, slake zone, rock zone and bed material zone. Erodibility of the channels is determined using multiple techniques including reach hydraulics and stream power computations, submerged jet testing, slab entrainment thresholds, and slake durability rates. Procedures are based on both empirical and modeled time series estimates of channel erosion. Field and modeled results support rates of erosion of up to four inches per year. Rates are tied to flow regime, climate, and type of channel bed and banks.