Effects of longitudinal slope, roughness, and rainfall on drainage parameters

The hydrologic flow on a roadway during and after a rainfall event has a great effect on the level of safety provided by the roadway system. This research focuses on the effects of rainfall, surface roughness, and longitudinal slope on sheet flow parameters, including Reynolds number, friction factor, and Manning's n. Experimental tests are performed on 1%, 2%, and 3% longitudinal slopes for three different surface roughnesses in Rain and No Rain conditions. Regression analysis is completed to determine the relationship between Reynolds number and friction factor, as well as between Reynolds number and Manning's n. Data is presented that shows the varying effect of slope and rainfall on different surface roughnesses. It is determined that rainfall has little effect on sheet flow characteristics compared to the significant effect of surface drag. Longitudinal slope was determined to have a significant effect on sheet flow parameters, depending on the surface roughness. Finally, it is illustrated that sheet flow parameters are consistent at different points on the roadway by comparing values from three measurement stations on the surface.Environmental and Water Resources Engineerin