Landscape Change and Vegetation-Channel Interactions in an Estuarine System: Tijuana River Estuary, San Diego, CA

Authors: Adriana Martinez*, Southern Illinois University -Edwardsville
Topics: Water Resources and Hydrology, Geomorphology, Coastal and Marine
Keywords: Tijuana River Estuary, vegetation, roughness, GIS, land cover change
Session Type: Guided Poster
Day: 4/8/2020
Start / End Time: 8:00 AM / 9:15 AM
Room: Agate A/B, Hyatt Regency, Third Floor
Presentation File: No File Uploaded


Climate change can alter many environmental factors, including sea level and storm frequency and severity (Scavia et al. 2002; Zedler 2011). Along estuaries, each of these impacts can cause changes in ecosystem function given that estuary elevation dictates several factors including salinity content, habitat type, and flow conditions (Harley et al. 2006; Scavia et al. 2002). We examined aerial imagery to determine major changes in estuary land cover over time (1995-2016), examined sedimentation patterns by calculating vegetation roughness of two dominant lower marsh species: Salicornia pacifica and Spartina foliosa and directly measured sediment deposition within plant stands at multiple elevations to model how vegetation may be interrupting flow and affecting deposition. Plant roughness for S. foliosa was significantly higher and, based on modeling, each species creates different water surface and channel velocity conditions that could alter deposition patterns. Vegetation inventories and sediment size deposition analysis show that S. foliosa occupies those areas closest to the channel, is most frequently inundated, and has the smallest sediment sizes present. Sediment size increases with distance from the channel and is more commonly dominated by S. pacifica. These areas, typically 0.5-1m above channel bottom elevation, experience the highest volume of sediment deposition. Modeling and direct measurements of deposition indicate that water velocity is impacted by plant stands and deposition is occurring in areas close to the channel. Continual monitoring should be carried out to determine how vegetation-induced sediment behavior, combined with anthropogenic land-use change and sea level rise, influence estuary elevation and land cover.

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