Testing the impact of at-source stormwater management on urban flooding through a coupling of network and overland flow models

In many urban catchments, stormwater flooding is a serious problem. Low-impact development and the use of stormwater control measures (SCMs) have the potential to mitigate such flooding, but this potential is highly context specific and remains largely untested. In this study, we tested the potential of SCMs to impact stormwater flooding in a peri-urban catchment by coupling a one-dimensional 1D stormwater drainage model with a two-dimensional (2D) overland flow model. We predicted consequent flood dynamics for a range of storm events and management scenarios. We found that realistically extensive application of rain tanks and infiltration trenches is most effective in mitigating stormwater flooding for common-to-rare storm events [5- to 20-year annual recurrence interval (ARI)] with short durations, such that the events have rainfall depths that are similar to the retention (or storage) capacity of commonly used small-scale SCMs. Retention of stormwater also has the ability to mitigate overland flow intensity, positively impacting pedestrian safety and reducing potential building damage for rare events with ARIs above 20 years. In addition, SCMs also provide benefits to alternative options such as pipe upgrades, through their protection of receiving waters and enhancement of urban landscape amenity. (C) 2015 Wiley Periodicals, Inc.