Time to bucket up!

Abstract

Bucket up! Can large private properties provide substantial coastal city flood mitigation under climate change? Protecting coastal cities from flooding under climate change is challenging. Conventional approaches like walls and dykes are inadequate and there is risk of under or over investment. Green stormwater infrastructure can help, but public land is often missing. Small buckets on private land may not be enough. We need a more strategic approach for larger buckets to protect communities. Can industrial lands provide a better solution? We assessed the potential of large industrial parcels in Christchurch for flood mitigation under different climate change projections. Industrial parcels could provide substantial flood mitigation within three of six study catchments, reducing the severity of climate change-induced increased runoff volume to current flood protection level under any climate scenario in the immediate future (2030-2050). Industrial land in two of these catchments could also reduce runoff to this level in the distant future (2080-2100), and under larger storm events, though not for all climate scenarios. Finding the right bucket in the right place and at the right time: A novel methodology for developing adaptive flood mitigation strategies with climate change Traditional flood prevention is difficult to plan for one-time investment due to high uncertainty of climate change projections in the long term. Networks of Green stormwater infrastructure (GSI), in contrast, can be designed and rolled out when needed as climate change impacts increase. Although GSI on large developed land can provide substantial flood mitigation, parcels have different flood mitigation capabilities over time. However, an effective methodology to evaluate and compare them is missing. Here, we present the Hydrology-based Land Capability Assessment and Classification (HLCA+C) methodology which builds on the strengths of existing methodologies. It was applied to a Christchurch catchment, leading to the identification of an adaptive GSI flood mitigation network for the next 80 years that can mitigate flooding almost as effectively as the major climate change scenario.