Tiao J. Chang

Principal Investigator


Yanhui Fang

Research Assistant





The work upon which this report is

based was supported in part by funds provided by

the Ohio Environmental Protection Agency

Columbus, Ohio.





200 Stocker Center

Hydrology and Hydraulics Laboratory

Ohio University, Athens, Ohio 45701








July 2004








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 Ohio will greatly enhance the understanding of bankfull characteristics. It will further provide information to assess impacts of projects for modifying channels and a useful tool to design channels for minimizing these impacts. 

Twelve sites whose drainage areas ranging from 7.8 to 115.7 square miles in the Hocking River Basin were selected in this study for the bankfull channel geometry determinations including cross-section area, width, and depth. These parameters form the basis to develop the relationships between bankfull dimensions and their associated drainage areas in the sasin to provide quantitative measures of channel characteristics in the southeast region of Ohio.  Based on the data collected and the results analyzed, it is concluded that channel dimensions of cross sectional area and width are strongly related to their drainage areas and the channel depth is moderately related to the drainage area.

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, Columbus, Ohio is gratefully acknowledged.  Ohio University provided in part the in-kind support for carrying out the project and completing the thesis upon which this report is based.  The appreciation is extended to Ms. Lauren Lambert of Ohio Environmental Protection Agency for her assistance and guidance in the administration of this project.  Suggestions and assistances provided by Mr. Dan Mecklenburg of Ohio Department of Natural Resources and by Mr. Dan Imhoff of Ohio Environmental Protection Agency are extremely valuable for the completion of this project.  The field survey assisted by two former students of Civil Engineering Department of Ohio University, John Schaad and John Smith, are notably acknowledged.


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.