ABSTRACT
Seldom does flow move far before entering some kind of channel. Consider, for example, runoff from the roofs of houses in urban areas. The water soon enters gutters, flows into a downspout, and goes through a buried pipe to the street curb. The water then flows along the side of a road and in many parts of the country will then enter a drain leading to a subsurface stormwater system. Even in rural areas, runoff from agricultural fields frequently flows into grassed waterways or open ditches. Does this mean that the procedures described in Chapter 5 have little or no usefulness? Certainly not, for they are used in the design of gutters, pipes, stormwater systems, waterways, and ditches. Also, flow in small conveyance systems is often approximated as similar to overland flow because it is not practical to divide every watershed into subwatersheds representing individual houses and fields.
