Watershed Analysis for Small Coastal Newfoundland Communities

Climate change is projected to increase frequency and magnitude of extreme precipitation events and increase temperatures that will impact infrastructure assets. As a result, Newfoundland's many small, coastal and rural communities face increased risk from rising sea level, more intense precipitation and flooding, infrastructure failure and coastal and riverbank erosion. The response of a watershed to rainfall, and how development within a watershed will be impacted and, in turn, impact the hydrological response is vital to planning and design of infrastructure. The objective of this research is to look at land development and adaptation plans to minimize the climatic impacts on infrastructure and town assets. Two-dimensional (2D) watershed models (PC-SWMM) were developed for several small Newfoundland coastal communities. Scenarios representing multiple design storms for several return periods were run to assess vulnerability of storm-water infrastructure to potential land use and projected climate change. Model calibration was done using simulation metrics from the basin transfer method. The virtual watershed was designed to identify factors contributing to the high levels of vulnerability and risk and identify best adaptation and risk management strategies while considering uncertainties. Results highlighted vulnerable zones and some assets that require maintenance or require replacement to meet possible future flows. The most important highlight of the study was protecting natural infrastructure such as wetlands and greenspace to help reduce the pressure on the assets themselves. Future work should include better tracking of community assets and related information to help with assessment and planning and protect natural "green zones". Using natural drainage helps keep infrastructure costs and helps reduce potential damage.