Laserfiche WebLink
<br />a. Gradually varied flow <br /> <br />In uniform flow, the flow depth (called the normal depth) is <br />constant and equations such as the Manning's equation may <br />be used to establish hydraulic conditions, <br /> <br />In gradually varied flow, the flow depth is not constant and is <br />either larger or smaller than the normal depth, due to <br />changes in bed slope, cross section, flow obstructions (e.g., <br />bridges), etc, <br /> <br />Evaluation of a gradually varied flow profile accounts for <br />friction losses, but ignores acceleration forces. Callculation <br />of gradually varied flow profiles are readily completed by <br />computer programs such as WSPRO and HEC-2, <br /> <br />b, Rapidly varied flow <br /> <br />In rapidly varied flow, changes occur in a very short reach, <br />such that the boundary resistance and friction losses, <br />important in gradually varied flow, are comparatively <br />insignificant. <br /> <br />Examples of rapidly varying flow include flow-through bridge <br />openings, over spillways, through expansions and <br />contractions, hydraulic jumps, and others. <br /> <br />Evaluation of rapidly varying flow considers only accE~leration <br />forces and ignores friction losses. <br /> <br />3.18 <br />