With wet weather comes erosion . . . and we have certainly had plenty of both this winter.

When erosion induced sedimentation travels downstream it can cause problems—reducing the capacity of rivers, causing pollution by carrying chemical runoff, and decreasing the quality of water by changing the chemical content and reducing oxygen levels.

There are several restoration techniques that can be used to control the movement of water over the soil surface. Choosing the most appropriate technique depends on whether you want to reduce the velocity of the runoff, increase the surface water storage capacity, or simply dispose of excess water safely. At the Glenwood Open Space Preserve, we inherited an erosional gully east of Chivos Pond where we have been implementing stabilization structures with the intention of reclaiming and controlling erosion by reducing the velocity of the runoff.

The Land Trust Stewardship team implemented a hybrid of mechanical and vegetative practices by building small brush dams with locally available materials such as coyote brush, Douglas fir, and willows to trap sediment and reduce channel depth and slope. The first step required cutting straight willow branches and embedding them into the soil across the erosional gully. These willow stakes will serve two purposes: first, they will hold the permeable dam in place and, second, they will root when planted in moist soils, adding complexity and increasing vegetative cover.

Coyote brush and Douglas fir bows were laid perpendicular to the willow stakes, creating a brush apron downstream of the dam, which will prevent water from undercutting the structure. Finally, the team packed brush between the willow stakes to create a permeable dam to capture and retain sediment that would otherwise be carried downstream.

Increased erosion in our landscapes is seen as a response to pressures brought about by a growing world population. By increasing impervious surfaces (paved roads, parking lots, etc.) water runoff that would otherwise be absorbed into the ground is concentrated into fewer locations, increasing its potential to impact nearby soil. 

The Glenwood Open Space Preserve is home to habitats such as grasslands and wetlands that are easily threatened by unchecked erosion. Loss of habitat, especially in a preserve that is home to listed and rare species can be problematic. By working to slow existing erosional features, we hope to protect the varied habitats present at the Glenwood Open Space Preserve.

Want to read more about erosion control at Glenwood? Check out this article about the Canham Meadow Restoration project.

https://landtrustsantacruz.org/articles/glenwood-meadow-restoration