The City of Surrey completed a study that suggested that rainfall intensity is trending upward. The City revised their IDF curves across the City, and then conducted a detailed study to project IDF curves to represent future conditions with climate change. The projections suggest that rainfall increases may be much higher than anticipated, and recognized the impact this could have on their drainage level of service.
Following the rainfall analysis, the City retained Associated Engineering to use that information to develop a climate change rainfall adaptation strategy for their drainage infrastructure.
As part of this project, our team looked at three case study areas representing different development types, and different watershed characteristics, in order to assess the impact of climate change on the drainage system.
We developed a combined 1-D pipe model / 2-D overland flow to assess the impact of increased rainfall over three time horizons (2030s, 2050s, and 2080s). Integrating the model output and the City’s existing GIS data, we developed routines to estimate the cost of flood damage on a lot-by-lot basis. This innovative method allowed us to develop a suite of adaptation measures that take into account both the cost of implementation, and the cost of flood damage avoided, so that upgrades can be prioritized to those areas most at risk of flood damage.