Variation of Manning’s coefficient with channel stage

Although Manning's roughness coefficient is known to vary with river stage, information on this aspect is limited, and practitioners have to resort to trial-and-error approaches or rely on their judgment to quantify the variation. This research was aimed at investigating the variation patterns of Manning's roughness coefficient over depth. Investigators conducted an extensive laboratory experiment using a fairly long and large channel, in the shape of half of a compound cross section, to simulate natural rivers. This experimental channel allowed a comprehensive investigation of both uniform and composite roughness elements along the channel's wetted perimeter. Data were taken from both cases: when flow was restricted in the main channel (to simulate a prismatic channel) and when it covered the floodplain. In addition, the investigators converted data from other researchers to verify factors not covered in this study. The researchers found that while geometry and roughness patterns can both affect the magnitude of Manning's coefficient over depth, the effects vary in prismatic and floodplain channels. Experimental data were used to identify the variation patterns of Manning's roughness in the floodplain channel as well as the effects of varying roughness distribution in the main channel and floodplains. Investigators also made a number of recommendations regarding the equations that should be used to quantify the variation of the overall Manning's n value for a channel section. Suggestions were made as to the specific use of these equations, including the number of subareas within the channel to be considered, the type of division lines between the subareas, and the ranges of applicability of the equations.U.S. Department of the InteriorU.S. Geological SurveyOpe

Cache River Basin: Hydrology, Hydraulics, and Sediment Transport: Volume 2: Mathematical Modeling

published or submitted for publicationis peer reviewedOpe

Appendices For: Hydraulic Investigation for the Construction of Artificial Islands in Peoria Lake

published or submitted for publicationis peer reviewedOpe

Hydraulic Investigation for the Construction of Artificial Islands in Peoria Lake

published or submitted for publicationis peer reviewedOpe

Impacts of Barge Traffic on Waves and Suspended Sediments: Ohio River at River Mile 581

published or submitted for publicationis peer reviewedOpe

Cache River Basin Project: Progress Report

published or submitted for publicationis peer reviewedOpe

Waves Generated by Recreational Traffic on the Upper Mississippi River System

Movement of recreational boats in a waterway such as the Upper Mississippi River System (UMRS) generates waves that can impact the river biota and the stability of the shorelines. This report presents the results of a research project undertaken to determine the characteristics of waves generated by recreational craft within the UMRS. To meet the goals of the project, 246 controlled runs were made with 12 different boats at two sites, one on the Illinois River and the other on the Mississippi River. Data from the controlled runs indicated that recreational boats can generate from 4 to 40 waves per event, with a mean of about 10 to 20 waves. These waves can last from 6 to 40 seconds or more. Average wave heights for these controlled events varied from 0.01 to 0.25 meter, with a median of about 0.06 to 0.12 meter. The maximum wave height was as much as 0.6 meter. The wave data from the controlled runs were used to develop a regression equation for estimating maximum wave heights on the basis of the speed, draft, and length of the boats, and their distance from the measuring point. This relationship is now recommended for use in determining wave heights generated by recreational boats. Data from uncontrolled boating events on the Mississippi River indicated that as many as 704 boats passed a highly used area of the UMRS in a single day on a busy weekend. Up to 120 boats passed the site in a single hour. Sustained movement of recreational boats can generate essentially continuous waves, giving the appearance of random waves at or near the shoreline. During the day of heaviest boating activity at the Mississippi River site, the maximum wave height measured was 0.52 meter, and the average for the whole day was 0.065 meter. Analyses were also performed by partitioning the wave heights on an hourly basis. These analyses indicated that significant wave height can reach a magnitude of 0.4 meter or higher, and maximum wave height can reach 0.5 meter or higher. Calculations were also performed to show that for waves of 0.4 meter in height to develop at the Mississippi River site from wind alone, the wind would have to be blowing at a speed of about 26 meters per second (58 mph) across the measuring point. Wave energies were computed by partitioning the waves into five-minute intervals. These analyses showed that the shorelines are subjected to wave activity of fairly high intensity. No analyses were performed to determine the bank erosion potential or sediment resuspension characteristics of the waves generated by recreational boats. However, existing mathematical formulations can be used to analyze the stability of banks composed of noncohesive bank materials. Additional research should be initiated to determine the effects of recreational boats on the stability of cohesive and noncohesive banks, and the way in which wave activity resuspends bed materials.Ope

Cache River Basin: Hydrology, Hydraulics, and Sediment Transport: Volume 1: Background, Data Collection, and Analysis

published or submitted for publicationis peer reviewedOpe

Appendices for Volumes 1 and 2: Cache River Basin: Hydrology, Hydraulics, and Sediment Transport

published or submitted for publicationis peer reviewedOpe

Appendices for Volumes 1 and 2: Cache River Basin: Hydrology, Hydraulics, and Sediment Transport

published or submitted for publicationis peer reviewedOpe