Resiliency in the Wapiti Watershed

Floodplains

⏺Floodplains are a normal and critical part of a stream or river. This means that a river or stream needs a lot more room than just the channel. So where we usually see water is just a small portion of the stream or river.
⏺Flows fluctuate from year to year and flooding is an important part of how streams and rivers function.
 
The graphic on the right shows how wide a floodplain is compared to the stream channel. On the far right you can see modelling done by TerrainWorks for a watershed that shows the area submerged by floodwaters at different flows.
 
💡The take away is that streams and rivers need room to flood.

This project aims to improved the resiliency of the Wapiti Watershed. Resiliency can be thought of as the ability to bounce back from a disturbance.  In the case of the watershed we are thinking about the ability of the watershed to bounce back from things like drought and flood to continue providing services that we need. These services (Ecological Goods and Services) include water quality, water storage, fish habitat, groundwater recharge as well as recreational and spiritual opportunities among other things.

There are two sites for this project and each will have specifics techniques employed.

The first site involves a river bank that is eroding and affecting the people who live there.  Rivers move over time as do river banks so we are not pursing a hard armouring (eg., concrete or rip-rap) approach.  Rather we will be installing coarse woody debris which will allows the bank to move some but reduces the major or catastrophic bank collapses by reducing the force of the water and intertwining the coarse woody debris with saplings growing on the bank. We will be planting trees and doing some livestaking to restore the important vegetative component to this bank. An important of this is always allowing enough room for the river or stream, which includes the floodplain. This coarse woody debris will perform a range of functions including bank stabilization, flow moderation and providing fish habitat.

Washed out road at one of the sites.
Graphic showing some of the benefits of coarse woody debris.

The other site involves erosion occurring in a field where a stream has become disconnected from its floodplain and created new channels during high flows cutting through the neighbouring field. In working to maintain both a functioning stream and agriculture on the landscape we will be reconnecting the stream to its floodplain and allow the floodplain to dissipate the erosive force of high flows and thereby reduce erosion in the field.  This is of course requires adjusting management practices (farming) to how water is now across the landscape and ensuring that the stream has floodplains that  can accept the higher volume flows. Earthworks will be completed to reconnect the floodplain and native vegetation will be reseeded to support its resiliency.

Field erosion where the stream became disconnected from its floodplain.
Flow chart showing approach to dealing with erosion.

We are thankful for the support and funding that we have received for this project.

This project is undertaken with the financial support of

Many thanks go to the landowners who have allowed us to work alongside them in this project. Additionally, we rely on the expertise of our good friends and partners including: