Seasonal flooding and wetlands

Seasonal flooding and wetlands

Our wetland habitats depend on the seasonal ebb and flow of water. Working with this natural process brings wide-ranging and wonderful benefits - Vanessa Barlow, Living Landscapes Assistant for the River Derwent explains.

Our floodplains - land next to rivers naturally part of the river system and covered by water only when flooding occurs – should act as natural sponges. They can soak up excess water and create natural buffers that store and slow the flow of rainwater and snow meltwater. They provide areas where rivers can safely spread out and valuable wetland habitat can be replenished.

However, studies show* that 90% of floodplains no longer function properly in England.  Climate change predicts an increase in high intensity rainfall – which we’ve already seen in our region over the last few winters.  Straightening rivers, land-use change leading to draining and ploughing of meadows, marshes and floodplains, along with urban development have destroyed both the valuable habitats and their ability to naturally reduce flooding, creating a disconnect between rivers and their floodplains.

Winter wetland wonders

Flooding naturally occurs most often in winter because of an increase in rain and snow, low temperatures leading to less evaporation, and a reduction in evapotranspiration – where water and oxygen is release through leaves. All these factors lead to the ground becoming saturated. The increased volume of water also flows into the river where it’s joined by surface and drain water running straight off the tarmac and concrete in towns and cities.  

Winter flooding raises the wetland water table and provides food and roosting areas for tens of thousands of migrating wildfowl and waders. You’ll see this if you visit Yorkshire Wildlife Trust’s Wheldrake Ings reserve in the Lower Derwent Valley National Nature reserve during winter flooding. Ducks eat the seeds and insects that float to the surface, and waders eat other bugs and worms around the edge of the water where the soil is soft enough for their specialised beaks. These areas are also good for mammals and you might spot otters - opportunistic hunters in floodplains.

Summer meadows

Looking across these vast floodlands, it’s hard to imagine the colour and bird song that arrives here in spring. Winter flooding deposits sediment from the river releasing valuable nutrients that recreates the flower rich floodplain meadows, perfect for ground nesting birds like curlew and lapwing to feed and raise their broods. 

The abundance of wild flowers and grasses growing here in the summer months attract thousands of insects such as bumblebees, sawflies and hoverflies which will feed the thousands of breeding and migrating birds on their way between Iceland and Africa. One of the rarest is the corncrake, that relies on traditional hay meadows, recently returning to breed in the floodplains of the Lower Derwent Valley for the first time in decades.

Three cheers for our wetlands!

Well managed wetlands not only provide incredible wildlife habitats, filter and store water but are carbon stores too.  An increase of carbon in the atmosphere is the leading cause of climate change but vast amounts could be locked up in healthy soil and land richer in vegetation.  Wetlands are a natural and beautiful alternative to man-made structural flood protection – or can work alongside these barriers. Reconnecting floodplains to the river will undoubtably reduce flood risk further downstream.

 A network of wetlands, connected to our rivers will work for wildlife’s recovery and help us to better prepare for and manage the impacts of the climate crisis.

*Changing Face of Floodplains, 2017 - University of Salford & Co-op Insurance