Hydrology-based approach to storm water detention basin design using new routing schemes

The design of a storm water detention basin requires both hydrologic and hydraulic information. The basic hydrologic data include the inflow hydrograph and the allowable release. The hydraulic information of a basin requires prior knowledge of the basin geometry and outlet structures. With a known storage-outflow curve, the performance of the basin can be examined using a reservoir routing procedure. During the planning stage, a series of feasible basin sites is typically investigated for comparison and selection. During a feasibility study, the engineer faces a challenge as to how to derive the required storage-outflow curve when little hydraulic information is known. This paper presents a hydrology-based approach by which the storage-outflow curve can be approximated from the inflow hydrograph to the basin and the maximum allowable release from the basin. This hydrologic procedure significantly simplifies the storm water detention modeling technique and is a useful tool for regional drainage planning and alternative studies. In addition, this paper rearranges the continuity principle to derive two new reservoir routing functions. Both functions provide a direct solution using all variables at the same time step without iteration. The selection of routing functions is a matter of mathematical convenience.