Geomorphic assessments of the Touchet and Tucannon River basins help landowners and Columbia Conservation District staff make informed decisions about river restoration activities, identify potential project areas, and meet animal and habitat development goals as outlined by the district.
Lidar data was collected in 2018 of the
How can the geomorphic assessment help me?
By using the data gathered in the geomorphic assessment as reference, CCD and its partners are able to zero in on good “project candidate areas”. Topographical and fluvial data help determine what restoration activities will have the best results depending on the goals of the landowner. Restoration activities that increase channeling and floodplain connectivity help reduce erosion and reduce the impacts of flooding by allowing water to pass through multiple channels reducing the overall energy potential as compared to a single channel stream.
Why is the Touchet Basin a good candidate for restoration activities?
The Touchet Basin is a good candidate for restoration activities for several strategic reasons. First is that restoration activities will have multifaceted benefits for the local area. The Touchet River is large enough to produce and provide habitat for a lot of fish, as well as providing recreational activities. The river is not so large that restoration treatments struggle to stay in place, restoration treatments are not too large in scale, and are not as costly to construct since projects don’t have to be as large.
Can data from the geomorphic assessment have indirect impacts on surrounding areas?
Yes! Fluvial ecosystems are always changing and highly interconnected with the surrounding landscape. Projects may produce indirect benefits such as supporting non focal species (insects, fish, birds, etc) which support complex food webs in the area, which in turn helps create a more stable ecosystem. Reduced erosion in streams will allow for vegetation cover to change. Water quality may improve due to reduced erosion, healthy native submerged and terrestrial vegetation,
How does the geomorphic assessment determine the best potential areas for restoration activities?
What are some of the key components collected by the geomorphic assessment to help meet habitat and river basin goals?
- Floodplain Connectivity– the flow, exchange and pathways that move organisms, energy, and matter throughout a floodplain
- Measuring the existing connected floodplain as well as potential floodplain targets, and determine floodplain potential
- A connected, functional floodplain moderates the effects of floods and droughts on a river system by retaining water during periods of high flow and re- releasing it during periods of low flows.
- Channel Complexity– generally refers to heterogeneity of physical stream geometry or habitat
- By modeling river reaches at various flow conditions we are able to determine which areas of the river are complex and which are not
- Transport Capacity– the total amount of sediment a stream is able to transport
- Stream reaches that exhibit high transport capacity are often times incised,
- Gravel Augmentation Plan– Determine and target reaches and project areas that would revieve the most benefit from additional gravel supply.
- Gravel and other substrate materials are critical to aquatic organisms that live in rivers. Determining areas in the river basins where substrate is inadequate for fish and other aquatic organisms informs restoration activities.