Sediment supply, salt marsh monitoring, and the carbon budget of Humboldt Bay, CA
Suspended-sediment measurements are essential for coastal planning, resource management, and for assessing the sustainability of salt marshes in relation to expected sea-level rise. Suspended sediment can have positive or negative effects, depending on its characteristics and amount, and on the location and ecosystem services of interest. Sediment deposition in salt marshes helps sustain marsh elevations as sea level rises but deposition in ports and shipping channels necessitates periodic dredging. High turbidity limits the penetration of light which impacts photosynthesis and primary production in estuaries. In Humboldt Bay, where relative sea level rise rates are higher than regional averages due to tectonic-related subsidence there is a general lack of knowledge regarding suspended-sediment supply, turbidity, and vertical marsh accretion rates.
This pilot study will provide estimates of suspended-sediment supply and marsh accretion that will be used to manage existing salt marshes, prioritize and design salt marsh restoration, assess the feasibility for the reuse of dredged materials for tidal marsh restoration, and will inform the regional sediment management plan. These data will also provide necessary calibration information for future efforts to develop numerical models of sediment flux and marsh accretion.
This study is part of a State Coastal Conservancy project to monitor and assess water quality, sediment supply, and marsh accretion rates in Humboldt Bay, CA. The CAWSC will partner with the Western Ecological Research Center (WERC) to install and maintain monitoring equipment and to collect and analyze water quality samples and marsh accretion data using standardized USGS methods. The WERC will characterize vertical marsh accretion in four salt marshes and compare these to long-term marsh accretion rates determined by UCLA under a separate agreement. The CAWSC will measure continuous in-situ water quality data (turbidity, specific conductance, water temperature) in two of the marshes, will develop regression models to compute suspended-sediment concentration from turbidity, will conduct a storm-event deposition study, and will estimate suspended-sediment supply to Humboldt Bay from watershed sources under current and future climatic conditions using a coupled water balance model-sediment rating curve approach.
Suspended-sediment measurements are essential for coastal planning, resource management, and for assessing the sustainability of salt marshes in relation to expected sea-level rise. Suspended sediment can have positive or negative effects, depending on its characteristics and amount, and on the location and ecosystem services of interest. Sediment deposition in salt marshes helps sustain marsh elevations as sea level rises but deposition in ports and shipping channels necessitates periodic dredging. High turbidity limits the penetration of light which impacts photosynthesis and primary production in estuaries. In Humboldt Bay, where relative sea level rise rates are higher than regional averages due to tectonic-related subsidence there is a general lack of knowledge regarding suspended-sediment supply, turbidity, and vertical marsh accretion rates.
This pilot study will provide estimates of suspended-sediment supply and marsh accretion that will be used to manage existing salt marshes, prioritize and design salt marsh restoration, assess the feasibility for the reuse of dredged materials for tidal marsh restoration, and will inform the regional sediment management plan. These data will also provide necessary calibration information for future efforts to develop numerical models of sediment flux and marsh accretion.
This study is part of a State Coastal Conservancy project to monitor and assess water quality, sediment supply, and marsh accretion rates in Humboldt Bay, CA. The CAWSC will partner with the Western Ecological Research Center (WERC) to install and maintain monitoring equipment and to collect and analyze water quality samples and marsh accretion data using standardized USGS methods. The WERC will characterize vertical marsh accretion in four salt marshes and compare these to long-term marsh accretion rates determined by UCLA under a separate agreement. The CAWSC will measure continuous in-situ water quality data (turbidity, specific conductance, water temperature) in two of the marshes, will develop regression models to compute suspended-sediment concentration from turbidity, will conduct a storm-event deposition study, and will estimate suspended-sediment supply to Humboldt Bay from watershed sources under current and future climatic conditions using a coupled water balance model-sediment rating curve approach.