Climate change, rainfall patterns and the dichotomy of urban catchment responses.

Abstract:

With an increasing proportion of the world’s populations living in urbanized environments, the threat of flooding in a future climate is becoming a life critical factor. Available literature presents a strong case for storms to intensify with climate change resulting in an increased risk of flooding. Similarly, climate change is also projected to change seasonal distribution of rainfall in a way that increases the gap between these storm events. This presents an interesting question on how urban stormwater systems and how current methods to manage stormwater in developed environments might respond to these changes in rainfall patterns in a future climate. Here we use a detailed hydrologic and hydraulic model to show that while flood risk increases with more vigorous storms projected for the future, the seasonal distribution of rainfall can have a contrasting effect. This dichotomy of catchment response to in-storm and seasonal rainfall pattern changes increases the uncertainty in urban catchment response to rainfall in a future climate. This increased variability in catchment response presents and interesting challenge as how to best plan and build optimum urban stormwater management systems that provide an adequate level of protection to life and property. We suggest that urban stormwater design should change towards a more flexible system that can accommodate the larger variability in a future climate and provide a more robust response to future rainfall patterns.