Design of detention basin system along highways

A system of detention basins is an effective device for control of, storm flood both in terms of quantity and quality. The feasibility of designing detention basins for flood control by use of abandoned spaces near highway interchange and between highway embankments is investigated. Three algorithms are examined for routing inflow hydrographs through interconnected basins under various hydraulic and. hydrologic conditions. The programs solve for both the time dependent flow quantities and the extent of pollutant removal in the system for given inflows and pollutant trap efficiencies of the individual basins. The first algorithm is the extended version of the classical single reservoir routing and involves solution of a system of simultaneous nonlinear equations. The other two algorithms employ the so-called linearized or simplified versions of the continuity equation. The algorithms can take care of various possible combinations of inflow, type of connections between basins, and the boundary conditions at the outlet(s). Results from the three algorithms are comparatively analysed and the one which does not require excessively small time step for solution convergence is selected. The Kuo method employing the standard approximation for the mass conservation equations as in classical single reservoir routing is found favorable with respect to the time step required for convergence and hence is selected for application to design examples. Various basin arrangements are included to show the routing results with respect to quantity and quality for different combinations of storm inflows and outlet structure types. Interconnection between basins is found desirable both in terms of quantity and quality control of effluent.