A Method for The Preliminary Sizing of Flood Detention Basins With Dual Outlets

Authors: A. Melih YANMAZ

Abstract: Flood detention basins are widely used for storing flood water temporarily in storage reservoirs before releasing the attenuated runoff. In this study, a preliminary design method is presented to calculate the dimensions for flood detention basins with dual outlets. By investigating storage characteristics of some existing flood detention basins in Turkey with different inflow hydrographs, having 50 and 100 year return periods; regression equations were developed for various dimensions of dual-outlet detention facilities. This method determines the required flood volume that can be stored in the detention basin and the dimensions of the dual outlets which will provide the desired degree of attenuation. The method is limited to the design of a flood detention basin with no initial storage and with 1 m of bottom outlet diameter. It enables the designer to compare the various dimensions and costs of alternatives considered in the preliminary design. The dimensions of the existing detention basins are recomputed by this method. Costs of the detention basins obtained by this method are generally found to be less than the costs of existing projects.

Keywords: Flood, detention basin, dual-outlet, attenuation