Riverbank erosion rates in the White Clay Creek watershed, PA
Date
2018
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Publisher
University of Delaware
Abstract
The supply of sediment to stream channels and estuaries is currently a concern in the Christina River basin. The goal of this study is to provide one component of the sediment budget for the White Clay Creek watershed, a primary watershed in the Christina basin, by quantifying the rates of stream bank erosion and factors that control bank erosion rates. At carefully chosen field sites, bank erosion rates have been estimated using historical aerial imagery and exposed tree root dendrochronology techniques. To explain variations in measured bank erosion rates, a variety of controls are considered including riparian vegetation, near-bank velocity, bank material strength, and the effects of freeze-thaw processes. Results show that for banks with a considerable number of riparian trees the bank erosion rates stay below 12.5 cm/yr, while banks with either no trees, smaller trees, or a small number of trees have erosion rates that vary from 9.9 cm/yr to 36.1 cm/yr. No correlation can be found between near-bank velocity or bank strength versus erosion rates, and the same applies for those sites not dominated by riparian trees. There seems to be some correlation between the material in the basal layer of the bank and bank erosion rates with an average bank erosion rate of 17.0 cm/yr for banks with a basal layer of mostly mud, and 9.5 cm/yr for banks with a basal layer of mostly sand and gravel. The results of this study will later be used to estimate bank erosion rates for the entire White Clay Creek watershed.
Description
Keywords
Earth sciences, Bank erosion, Dendrochronology, Fluvial geomorphology, River, Sediment, White Clay Creek