Flood Management and Mitigation Seminar

Flood Management and Mitigation Seminar

Before 1996, there were only 3 flood-related disasters with economic impacts totalling over $500 million in British Columbia. In the 16 years since 1996 there have already been 12 disasters of this magnitude. Small towns are the most liable to flooding, and in response the province has constructed about 365 km of dikes in the Lower Fraser Mainland, the region where Metro Vancouver is situated. In the spring of 2012, a team of delegates from the Consulate General of The Netherlands were invited to British Columbia to share their experience in managing the risk of coastal and river flooding with provincial and local government policy-makers and practitioners. Dutch authorities have constructed over 1200 km of dikes in response to increasing flood risks. A flood in the medium-sized Dutch city of Utrecht could see water 4 m deep with potential damages of $31 billion, and this increases with ongoing urbanization. Climate change is forecasted to increase the extreme highs and lows of seasonal river discharge in Western Europe. Gradual land subsidence (sinking) and water creeping under dikes slowly erodes the stability of dike infrastructure. The Netherlands’ flood management strategies have evolved over time to reflect these changing risks, local needs and lessons learned from centuries of flood management.

Video: Summary of the seminar

Currently, The Netherlands no longer supports raising dikes as their primary policy for defense against flooding. Instead, a range of solutions that take into account local conditions and opportunities can be seen being implemented. There are, on average, 2 major floods per century in The Netherlands, but the culture of flood adaptation now favours accommodation, which improves overall community resilience, rather than resistance, which tends to see higher damages during catastrophic events and higher overall community vulnerability. This shift fosters less engineered, less costly solutions in favour of more aesthetic, resilient approaches to managing hazards along coastlines and major rivers.

In Dutch cities, a “build up” approach which is implemented in BC through higher Flood Construction Levels, is implemented on a large scale. Expansion of the Maasvlakte, Europe’s largest sea port in Rotterdam, has adopted this strategy. A new-built neighbourhood in the city of Amsterdam was described by one visiting delegate as “an island of floating homes”. These approaches are similar in that they don’t attempt to keep water out, they just improve the resilience of infrastructure (i.e. they are designed to get wet and still function).

On Dutch shorelines, beach nourishment strategies capitalize on natural “sand engines” to keep rising ocean waters out. 12,000,000 m3 have been added to coastlines to date, with 2 – 4x this amount being deposited naturally by processes such as wind, water and waves (nature’s sand engine). In the words of one delegate: “just add a big pile of sand and nature does the rest”.
The Netherlands’ Delta program serves as an example of how outdated diking schemes have been modified to create improved, more publicly acceptable infrastructure. By constructing a “super-levee”, Dutch planners will be able to provide a multi-functional, unbreachable dike system with recreational land uses, a harbour and buildings on top of a stronger dike.

Their Room for The River program aims to improve the capacity (storing), slow down (retaining) and divert (draining / pumping) water from the major rivers that flow through The Netherlands and is a Dutch flagship demonstrating the efficacy of long-term planning (in the order of 10 years, according to one visiting delegate), inter-governmental collaboration, public-private partnerships and community engagement in 30 different sites by 2015. They have made a commitment to achieving win-win strategies through strong public engagement, and delegates recounted numerous examples of improvements to government proposals that were developed by communities which then became official policy. Implementation has begun of these highly refined schemes involving a mix of strategies that involve excavating river beds, designing by-pass routes for future river overflows, integrating proposed future development and railway rights-of-ways, improving green space amenities, designing transportation tunnels under dikes, buying out land (expropriation), and most importantly a careful analysis of current and future land use.

All of these approaches face unique challenges for planners and decision-makers, not the least of which is available funding, which communities in The Netherlands benefit from to the tune of several billion annually (in contrast to BC’s $10 million per year). But the World Bank estimates the return on these investments to be in the order of 3:1 to 10:1 (even as high as 30:1 in the case of Manitoba). By the end of this seminar, it became clear that there is an additional element of success consistent across all of the case studies discussed: the need for long-term, participatory planning processes to begin developing holistic, site-specific solutions. Here in BC, members of a local stakeholder group in Delta were involved in such an exploratory process, the results of which can be seen here: www.delta-adaptation-bc.ca. Planners, engineers, residents, researchers and local politicians were involved in this research exercise, described below in this interview conducted with landscape planner David Flanders during the seminar:

Video: Current research on flood management and mitigation in Metro Vancouver, BC

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