INVESTIGATION OF RELATIONSHIPS BETWEEN BANKFULL CHANNEL GEOMETRIES AND THEIR ASSOCIATED WATERSHED AREAS
IN THE HOCKING
Tiao J. Chang
The work upon which this report is
based was supported in part by funds provided by
200 Stocker Center
Hydrology and Hydraulics Laboratory
WATER RESOURCES TECHNICAL REPORT NO. 17
Stream channels are constructed and maintained by complex processes including forces of waters, suspended sediments, and bed load materials. Though the formation process of channels is complex, there are quantifiable and consistent patterns for the process, especially at the bankfull stage. The stability of a stream channel is generally defined as the ability to carry the water and sediment while maintaining dimension, pattern, and profile without degrading or aggrading channel dimensions over time.
However, any changes of geomorphic parameters will trigger channel adjustments to reach a new equilibrium. A geomorphic approach quantifies the physical characteristics of stream channels and identifies patterns common to a watershed or region. It is believed that channel maintenance is most effective at the bankfull stage, while the associated discharge carrying sediment loads, forming and removing bars, and forming and changing bends results in average characteristics of stream channels. Hence, bankfull stage and its corresponding dimensions are a useful measure in determining channel characteristics. This measure provides a valuable tool for assessing characteristics of stable stream channels, which have been used in both regulatory programs and environmental impact analysis.
To develop possible
relationships between the bankfull dimensions and
their corresponding drainage areas in the major regions of
Twelve sites whose drainage
areas ranging from 7.8 to 115.7 square miles in the
Furthermore, the regression equations were developed to relate bankfull cross-section area, width, and depth to their associated drainage areas as given in the following table, where DA = drainage area in mile2, Abkf = bankfull cross-sectional area in ft2, Wbkf = bankfull width in ft, and Dbkf = mean bankfull depth in ft.
Abkf = 75.921DA0.467; Wbkf = 26.368DA0.270; Dbkf = 2.859DA0.205
The funding supported in part by the Ohio
Environmental Protection Agency,
Contents of this report do not necessarily reflect the views and policies of the Ohio Environmental Protection Agency, the Ohio Department of Natural Resources, or any organizations above, nor does mention of trade names or commercial products constitute their endorsement or recommendation for use in the related agencies.