of Coastal Planning Leads to Increased Risk of Flood Damage
By Tony Bowron*
In Nova Scotia, the lack of clear municipal or provincial guidelines
has led to unregulated residential and commercial development in coastal
areas. Building houses and roads on floodplains and across rivers or
wetlands leads to the kind of flood damage experienced last week in
much of Nova Scotia. Last week's heavy rainfall caused bridges and roads
to wash out and caused flooding in many low-lying areas of the province.
Coastal floodplains are low-lying lands such as salt marshes and river
valleys that help to buffer and stabilize coastal systems. In natural
coastal landscapes, floodplains are sponges that absorb and gradually
release excess water back into the system. This protects inland and
downstream areas from flooding during heavy rainfall.
In recent years, residential and commercial development along the coasts
has increased in scope and intensity. In Nova Scotia, there is no comprehensive
provincial legislation suggesting guidelines for coastal development
or the protection of natural coastal buffer zones. As a result, natural
floodplains are covered with houses and parking lots, and roads and
causeways bisect wetlands.
This infrastructure in turn has to be protected by roads, dykes, culverts,
and seawalls to prevent the natural entry of the sea into low-lying
coastal lands. Ironically, these coastal protection systems compound
the problem because they are designed to limit the flow of water. "Watersheds
are like bathtubs. If you place something over the drain that blocks
the hole partially or completely, then the water can't escape and eventually
spills out of the tub." explains Tony Bowron, chair of the Ecology Action
Centre's Coastal Issues Committee (CIC). "We build dykes, dams, causeways,
and install culverts in an attempt to prevent the natural flow of the
daily tide across coastal salt marshes and into natural tidal rivers,
but it is freshwater that builds up behind these structures and cause
The Ecology Action Centre has conducted tidal audits to assess the status
of tidal crossings in Minas Basin. They examined culverts, causeways
and bridges to determine how well daily tides could flow into, and freshwater
out of, the crossing openings. This research identified that over 50
per cent of the tidal crossings in Hants and Colchester Counties are
partially or completely restricted.
Improperly sized culverts increase the likelihood of coastal flooding.
When huge volumes of water, such as those experienced last week, reach
tidal crossings with small culverts, the culvert openings are too small
for the increased water volume. It was the built up force of the backed-up
freshwater (called a freshet), which was unable to drain quickly enough,
that led to bridges and roads washing away last week. Throughout Nova
Scotia, 47 bridges were damaged or washed away after the heavy rains.
We can learn from the destruction. The Ecology Action Centre urges the
Department of Transportation and Public Works to view last week's events
as an opportunity to replace restrictive crossings with properly-sized
and placed structures that allow for a more natural hydrological regime.
Tony Bowron says, "If we built our roadways and constructed our coastal
communities in balance with the daily flow of tidal waters up stream,
then we would be less likely to suffer the devastating flooding events
like we experienced last week. We would be maintaining the buffering
capacity of coastal areas."
The Coastal Issues Committee is also promoting the development of a
Coastal Areas Protection Policy similar to that adopted in New Brunswick.
Under this policy, coastal development activity is governed using established
zones in which various kinds of uses are permitted. Municipal governments
are required to manage growth on coastal lands and protect coastal features,
such as wetlands. This will ensure better planning of development activities
as well as greatly improved protection for the future.
For Jennifer Graham, Outreach Coordinator for the Coastal Issues Committee's
salt marsh restoration project, "a comprehensive policy would be step
in the right direction, but it would still require legislation and enforcement
to ensure implementation and accountability".
* Posted Wednesday, April 16, 2003. For more information about the tidal
restriction, coastal development or the Ecology Action Centre's Salt
Marsh Restoration Project, please contact Tony Bowron, Chair, Coastal
Issues Committee, 442-0199, firstname.lastname@example.org.