Generalized Numerical Solution for Detention Basin Design

A particularly useful generalized numerical solution for detention basin design is presented and sets the stage for practical applications for roof detention and the rationale and use of such a solution for detention basin design more generally. The generalized numerical solution provides results that can be applied to practical problems in certain cases and demonstrates the general importance of storm duration. The method utilizes a trapezoidal inflow hydrograph, which includes the important effect of storm duration based on the modified rational method. Convenient charts are presented to display the relationship between the variables. The derivation provides the basis for specializing the method to provide generalized curves applicable to storage detention on roofs. Although the results presented herein are more generalized than those presented by other writers, certain other methods are shown to compare favorably for special cases. An added perspective is provided on some of those other methods. Soil Conservation Service TR-55 curves are included in the comparisons, which demonstrates their limitations. An example demonstrates application of the generalized curves.