Effectiveness of Rainwater Harvesting Systems for Flood Reduction in Residential Urban Areas

Gabriele Freni,Lorena Liuzzo

doi:10.3390/w11071389

Abstract

Rainwater harvesting (RWH) systems have many benefits being an effective alternative water supply solution, not only in arid and semi-arid regions. Also, these systems can be useful in the reduction of flood risk in urban areas. Nevertheless, most of the studies in literature focused on the potential of RWH in reducing water consumption, whereas few examples examined their efficiency in the retention of stormwater in flood-susceptible residential areas. The aim of this work was to investigate the reliability of RWH systems in terms of stormwater retention. Specifically, the performance of RWH tanks to supply water for toilet flushing, in more than 400 single-family houses in a residential area of Sicily (Southern Italy) was analyzed. The area of study was chosen due to its high susceptibility to flooding. A flushing water demand pattern was defined using water consumption data collected during a measurement campaign. The yield-after-spillage algorithm was used to simulate the daily water balance of the RWH tanks. The effect of the RWH implementation on flood volumes in the area of study was quantified using FLO-2D. Results point out that the potential of neighborhood RWH installation in the mitigation of flood risk is highly related to rainfall amount.

Highlights

In the past, rainwater harvesting and domestic utilization have been very frequent practices in different parts of the world
In the context of increasing water stress, the installation of rainwater harvesting (RWH) systems represents a valuable and effective solution to reduce the use of drinkable water consumption for domestic uses in arid and semi-arid areas [1,2,3] and in urban areas [4,5]
The historical rainfall series recorded in the Palermo rain gauge during the 2002–2008 period was used to evaluate the performance of the RWH system installed in the 408 single-family houses included in the analysis

Summary

Introduction

Rainwater harvesting and domestic utilization have been very frequent practices in different parts of the world. In the context of increasing water stress, the installation of rainwater harvesting (RWH) systems represents a valuable and effective solution to reduce the use of drinkable water consumption for domestic uses in arid and semi-arid areas [1,2,3] and in urban areas [4,5]. The use of these systems has additional benefits, such as the retaining of flood from rainfall events and the consequent control of stormwater flood volume [6,7,8]. In the city of Champigny-sur-Marne (France), the effectiveness to

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