Flooding: Let’s be better prepared
Canada is still recovering from “the Great Flood of 2013” — which, at a cost of at least $5 billion, mostly in Alberta, appears to be exceeding the drought of 19992003, and the Manitoba-Saskatchewan floods of 2011 as Canada’s most expensive natural disaster.
These events would have been considered exceptional in the 20th century, but we are now seeing them every year in Canada and we are sharing this experience with the rest of the world. The recent example of extraordinary floods in Colorado is a horrific reminder of this. Atmospheric science tells us to expect even more extreme weather in the immediate future.
There are several things we can do to reduce our exposure to and damage from floods: better prediction, avoidance, and active mitigation.
■ Better prediction involves improved seasonal weather predictions three to six months in advance, better severe weather prediction days in advance and precise forecasting for rivers, streams, groundwater and lakes. Better prediction permits us to adapt in the short term by sandbagging for floods, managing reservoirs, and community evacuations in an orderly and safe manner.
■ Avoidance involves land-use zoning of appropriate locations for development and non-development based on careful and continuously updated floodplain mapping — without prejudice as to whether the floods are caused by rainfall, snowmelt, overland flood, ponding, streamflow, groundwater, lake level change, sea level change, wind storms or bank erosion. All water sources are connected and so the source of flooding should not be considered separately.
■ Active mitigation involves dikes, flood-control structures such as dams and detention ponds, channel modifications, and management of agricultural fields, urban development, forests and wetlands in the watershed. These structures, modifications or land-use practices must be designed and evaluated for their performance under known or anticipated extremes of water flow.
The ideal flood-damage reduction system involves all three components. Canadian hydrological and atmospheric science is highly competitive, efficient, collaborative and well regarded around the world and is able to deliver this.
Advancing the science and technology of prediction is not enough — the technological tools have to be used effectively by trained professionals with comprehensive institutional support.
Canada is exceptional amongst developed nations in that we have fragmented responsibility and capability for water prediction between multiple levels of government. Our federal government collects most weather and water data and predicts weather and drought — but it does not forecast floods, streamflow, lake levels, and water supply. The provinces have constitutional authority for water resource management and with this the obligation to predict floods, map flood zones and deliver frontline disaster management, reimbursement and repair.
As a result, the great flood of 2013, which started in Alberta and moved downstream across Saskatchewan into Manitoba along the Saskatchewan River system, was forecast as weather by the federal government and then as streamflow by three different provinces, with very different methods, attention and capabilities.
It is time we joined the rest of the developed world and started to save billions in flood damages by developing a first-class national strategy that would involve co-ordinated, integrated river basin-wide delivery of improved prediction and information to support flood forecasting, water management and implementation of flood avoidance and active mitigation strategies.
We can start with unified weather and water prediction models whose results are provided in real time so that the provinces can manage their water with the best possible information. These prediction systems need to be supported by enhanced weather and water observations from ground and satellite. Unified predictions are best accomplished by integrated riverforecast centres; these have been shown to be very successful in the United States. Some models even integrate university scientists along with multiple federal and state agencies to provide a powerful sciencebased water prediction and management centre.
Advance flood warning informed by unified water prediction systems would have helped in shortterm flood mitigation and a more orderly evacuation in Alberta this June. These same systems can help us plan for future flood plains, safer reservoir management, and allow us to better manage our forests and agricultural lands for long-term flood and drought mitigations.
We are in the midst of rapid hydrological change now and must move quickly to prevent this decade from being the most expensive for natural disasters in our history. It will take vision, co-operation amongst all levels of government and national leadership to improve our flood predictions — are we up to this?