Thinking Outside the Active Channel: Evaluating Water and Carbon Retention in a Low-Order, Designed River Corridor
The river network within anthropogenically modified watersheds conveys water and carbon more readily than in unmodified watersheds. Material conveyance has multiple negative consequences including elevated downstream flood risk and decreased carbon storage. Modern channel designs aim to mitigate these negative consequences by implementing design features such as constructed wetlands and large wood structures that promote water and carbon retention, enhancing watershed conditions. A field campaign was conducted within a low-order, designed channel one to two years post-construction in which design features (constructed wetlands and wood structures) were included to facilitate retention. Water level was measured continuously, and bed sediments were sampled discretely from September 2019 through November 2020. Data were processed to determine daily water presence/absence and particulate organic matter, then used to evaluate retention within design features and channel segments. The major contributions from this research will inform future watershed management initiatives aiming to facilitate retention within low-order channels.