Saving our rivers
Do you know what a river should look like? Really look like, that is.
Over hundreds of years, the shape and flow of our rivers and marshland has been dramatically altered to drain land for farming, housing and commercial development.
Instead of allowing our rivers to naturally meander and, during heavy rainfall, to slowly flood and deposit their silt and water on neighbouring floodplains, we have manipulated them.
Riverbanks have been straightened and deepened with steep banks which makes water flow faster and keeps it hemmed in.
With the impact of climate change, and more intense weather events, we are seeing heavy rainfall run off the surrounding land far too quickly, with the consequence of rivers flooding more often, and the impact of flooding affecting an estimated one in six properties in the UK.
Restoring our rivers and allowing them to meander again could be the solution to the problem.
As well as slowing down water, meandering rivers and their marshlands improve the quality of the water, create good habitats for wildlife and sequester carbon.
So what needs to be done and how? In the Lake District, the Cumbrian River Restoration Programme has already improved nearly 100km of river. One of the streams it has tackled was flowing into the River Eden and had been straightened and moved away from its natural course in the late 1700s.
It has now been restored, its canalised channel changed to a new route lower on the floodplain with features added including gravel bars, riffles and meanders to encourage a more natural action.
The results? Its capacity to store water has been increased, the flow of water and sediment downstream has been slowed and it is creating better habitats for trout, eels and Atlantic Salmon. When the river is high it can ‘gently spill’ onto the surrounding fields before draining away as the water levels drop.
In Norfolk, the Breckland Farmers Wildlife Network, a group of 58 landowners, want to ‘rewiggle’ a number of local rivers and connect them once again with their floodplains.
The region’s rivers currently move rainfall far too quickly towards the sea, eroding the soil and flooding downstream settlements.
The farmers’ plan would have biodiversity benefits and help much needed aquifers, an important source for irrigation of the land, to recharge for much longer.
Restoring our rivers is not just a British thing. Holland saw cataclysmic floods in 1993 and 1995, which made the Dutch rethink their approach to water management. Instead of channelling water off the land as fast as possible, they decided to reverse the process and keep it on the land for longer.
They are giving more room to rivers by restoring traditional wetlands and marshes cutting in meanders to slow the flow of water.
A pioneering project to restore 45km of the River Meuse has already reduced flooding and shown the wide-ranging benefits of working with nature.
It has been achieved by lowering large areas surrounding the river and broadening the river with banks of sand and gravel, varied shorelines and areas of woodland and grassland. This has created a ‘dynamic, braided river landscape which is allowed to flood and shift course naturally’.
The rewilding process has also led to the natural recovery of both plants and animals including beavers as well as greater biodiversity. It is also having tourism benefits.
As landscape architects, natural flood management is a hot topic at Land Studio.
It is one of the reasons why we recently launched our own in-house Civil Engineering division. There’s never been a better time for landscape architects and civil engineers not only to work closely together – but to work with nature.