Detention/retention storages for peak flow reduction in urban catchments: Effects of spatial deployment of storages

Stormwater management techniques for urban flood control have remained relatively unchanged in many practices throughout the world for most of the past 150 years. In the past 30 years, however, detention and/or retention techniques have been acknowledged as alternative approaches capable of meeting flood control objectives while providing environmental benefits and, sometimes, cost savings to developers and authorities responsible for stormwater management. In many places the use of detention and/or retention techniques has become common practice, particularly in urban catchments where open space for flood control is in short supply.This paper reports results of hydrological modelling undertaken in a hypothetical urban catchment using basic hydrographs generated by the DRAINS computer package.3 The two main aims of the modelling were 1) to explore the influence of position of retention and detention flood management elements on end-of-catchment catchment ‘peak flow’ outputs in hypothetical urban catchments, and 2) to provide clear, comparative information on the performances of the different strategies examined.The outcome from this study will not necessarily be applicable directly to all urban catchments, however it is possible that a refinement of generic flood control strategies could be developed as further related studies are undertaken in this area.