Evaluating the Effect of the Location and Design of Retention Ponds on Flooding in a Peri-Urban River Catchment

In order to reduce the flooding risk in urban and peri-urban river catchments, retention ponds or wet detention ponds are often used. However, there has been little work that uses distributed hydrological modeling to consider their optimum location and design in order to reduce the flood risk in a river catchment. This work considers two existing and two potential ponds in the 22.8 km(2) Braid Burn catchment, Edinburgh, Scotland. Using the Shetran physically based distributed hydrological model, the effect of these ponds on the river discharges for eight measured rainfall events and two design rainfall events is considered. The results show the larger Blackford pond is best at reducing the peak discharge at the catchment outlet. The other three ponds are designed to be almost the same. The potential pond in the upper part of the catchment reduces the peak discharge at the outlet; the pond in the middle at Oxgangs makes little difference to the peak discharge, while the potential pond in the lower part of the catchment increases the peak discharge at the outlet. These results show that when considering flood risk, the location of a retention pond within a river catchment is important, and it can make the flooding worse at the outlet if it is located in the wrong location. This work suggests the pond should be located in the upper part of the catchment, although the ideal location will depend on the catchment's shape and lag time.

Automated summary

In order to reduce flooding risk in urban and peri-urban river catchments, the optimal location and design of retention ponds are crucial. This study considers the effect of existing and potential ponds on river discharges in the Braid Burn catchment in Edinburgh, Scotland. The results show that the larger Blackford pond is most effective at reducing peak discharge, while the other three ponds have similar designs. The study highlights the importance of considering the location of retention ponds in flood risk reduction.