Abstract

The Baduwa’t River in Humboldt County, California, faces a legacy of channelization, poor land management, and severe flooding that has left high, dry floodplain terraces disconnected from the river and dominated by invasive vegetation. In response to sediment deficits during drought years, Riparian Enhancement Extractions (REEs) were introduced as an alternative gravel mining method that simultaneously presented opportunities for habitat restoration. This study evaluates five REEs along the Baduwa’t to identify the construction features and site conditions that promote successful riparian vegetation establishment. Findings show that REEs can create seasonal wetlands conducive to native riparian habitat reestablishment, when excavation is limited to the dry-season capillary fringe, allowing the site to drain annually. Successful sites, such as Pepe and Emmerson 1, demonstrated seasonal inundation patterns, fine sediment recruitment, and woody vegetation establishment. In contrast, Guynup failed to support riparian vegetation due to over-extraction, year-round ponding, and lack of drainage. Proximity to groundwater, rather than distance to the main channel, was a critical factor in habitat outcomes. Conceptual models incorporating construction depth, timing of seed release, and hydrological patterns suggest that specific hydrographs, particularly those from 2021, are aligned with successful recruitment of willows. However, climate change-induced shifts in snowmelt and runoff timing threaten natural germination cycles, especially for black cottonwoods, emphasizing the need for future intervention in riparian restoration. These findings inform best practices for integrating gravel extraction with ecological restoration in dynamic, drought-prone river systems.

Date

Spring 2025

Department

Forestry, Fire, & Rangeland Management

Concentration/Emphasis

Hydrology

Advisor/Professor

Andrew Stubblefield

Citation Style

APA

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