In many systems, particularly the relatively dry western United States, freshwater that historically flowed into estuaries has been diverted for drinking water, agriculture, and industry. The resulting changes to water flow profoundly altered estuarine ecosystems. CMHRP studies in this complex system inform resource managers tasked with balancing conflicting needs for water and restoration of critical estuarine and wetland ecosystems.
The San Francisco estuary, California, composed of San Francisco Bay and the Sacramento-San Joaquin Delta, is the largest estuary on the West Coast. It supports a diverse and productive ecosystem as well as economic activities such as shipping, recreation, and sand mining. Freshwater flowing into the delta is diverted for agricultural and municipal water supplies. Water diversions affect the estuarine ecosystem by altering the salinity gradient from fresh to marine waters. This ecosystem also faces many other threats due to urbanization and climate change, presenting complex management challenges. Large-scale ecosystem restoration, predominantly of tidal marsh, is underway in the bay and delta.
The CMHRP is involved in numerous projects in the San Francisco estuary, from habitat conservation, restoration, and resilience, to understanding the effects of sea level rise. CMHRP scientists study sediment transport in the estuary and how Earth processes and human intervention shaped the estuary, and contribute expertise on physical processes to collaborative interdisciplinary projects. Below we describe two of our projects.
Marshes occupy a narrow range of elevations relative to sea level, and they maintain elevation as sea level rises by accumulating sediment transported from adjacent waters. The success of many marsh restoration projects depends upon sediment accretion keeping pace with sea level rise, but the dynamics that deliver sediment to marshes are poorly understood. The CMHRP is studying sediment exchange between estuarine mudflats and fringing marshes at China Camp State Park in northern San Francisco Bay. CMHRP scientists measure sediment flux in tidal creeks within the marsh, wave and suspended-sediment properties in bay shallows, and wave attenuation and sediment trapping at the marsh edge. Results from the China Camp study will improve predictive models of marsh accretion and management of marshes threatened by sea level rise. This project is a collaboration with the San Francisco Bay National Estuarine Research Reserve.
Drivers of Aquatic Habitat
Water export from the San Joaquin Delta is managed by Federal (U.S. Bureau of Reclamation, USBR) and state agencies. These large water projects must be managed both to provide water reliably and to protect species of concern. Fisheries are in decline in the San Joaquin Delta, and several species, including the delta smelt, are threatened or endangered. Major habitat restoration efforts are planned to benefit delta smelt and other native fish species; however, the optimal physical habitat characteristics for these fish are not well understood. The CMHRP collaborates with the USGS Water Resources Mission Area in a USBR-supported study to address critical knowledge gaps about how shallow-water habitats support native fish species. The CMHRP investigates sediment dynamics (i.e., the motion of sediment), and the influence of wind waves on turbidity (the cloudiness of the water)—a habitat characteristic important to delta smelt—in two flooded agricultural tracts in the northern delta with different landscape configurations. Results will help guide ecosystem management actions, including flow manipulations and habitat restoration.
Explore the CMHRP Decadal Strategic Plan, and visit our San Francisco Bay project page
The CMHRP Decadal Science Strategy 2020-2030
This geonarrative constitutes the Decadal Science Strategy of the USGS's Coastal and Marine Hazards and Resources Program for 2020 to 2030.
Sediment Transport in Coastal Environments
- Overview
In many systems, particularly the relatively dry western United States, freshwater that historically flowed into estuaries has been diverted for drinking water, agriculture, and industry. The resulting changes to water flow profoundly altered estuarine ecosystems. CMHRP studies in this complex system inform resource managers tasked with balancing conflicting needs for water and restoration of critical estuarine and wetland ecosystems.
What is the Delta? This short video is intended to serve as an introduction to the Sacramento-San Joaquin Delta, and is the first in a series of four short videos highlighting USGS science in the San Francisco Bay and Sacramento-San Joaquin Delta estuary. This video orients the viewer to physical characteristics of the delta, the challenges facing it, and the work the USGS is doing, in coordination with our partners, to understand and characterize the delta ecosystem. Credit: Stephen M. Wessells, USGS » View the video The San Francisco estuary, California, composed of San Francisco Bay and the Sacramento-San Joaquin Delta, is the largest estuary on the West Coast. It supports a diverse and productive ecosystem as well as economic activities such as shipping, recreation, and sand mining. Freshwater flowing into the delta is diverted for agricultural and municipal water supplies. Water diversions affect the estuarine ecosystem by altering the salinity gradient from fresh to marine waters. This ecosystem also faces many other threats due to urbanization and climate change, presenting complex management challenges. Large-scale ecosystem restoration, predominantly of tidal marsh, is underway in the bay and delta.
Sources/Usage: Public Domain. Visit Media to see details.Dan Powers (USGS) and Rachel Marcuson (USGS) prepare to deploy a Gomex sediment corer from R/V Snavely in the Mokulumne River near confluence of San Joaquin River in the Sacramento-San Joaquin Delta, California. Credit: J.R. Lacy, USGS
Sources/Usage: Public Domain. Visit Media to see details.Josh Logan (USGS) surveys position and elevation of instrumentation to measure water level and suspended-sediment concentration in the marsh at China Camp State Park in Marin County, California, adjacent to San Pablo Bay (northern San Francisco Bay). Credit: J.R. Lacy, USGS The CMHRP is involved in numerous projects in the San Francisco estuary, from habitat conservation, restoration, and resilience, to understanding the effects of sea level rise. CMHRP scientists study sediment transport in the estuary and how Earth processes and human intervention shaped the estuary, and contribute expertise on physical processes to collaborative interdisciplinary projects. Below we describe two of our projects.
Marshes occupy a narrow range of elevations relative to sea level, and they maintain elevation as sea level rises by accumulating sediment transported from adjacent waters. The success of many marsh restoration projects depends upon sediment accretion keeping pace with sea level rise, but the dynamics that deliver sediment to marshes are poorly understood. The CMHRP is studying sediment exchange between estuarine mudflats and fringing marshes at China Camp State Park in northern San Francisco Bay. CMHRP scientists measure sediment flux in tidal creeks within the marsh, wave and suspended-sediment properties in bay shallows, and wave attenuation and sediment trapping at the marsh edge. Results from the China Camp study will improve predictive models of marsh accretion and management of marshes threatened by sea level rise. This project is a collaboration with the San Francisco Bay National Estuarine Research Reserve.
Sources/Usage: Public Domain. Visit Media to see details.Jenny White (USGS) and Lissa MacVean (USGS) deploy an instrumented frame in the shallows of San Pablo Bay (northern San Francisco Bay) from R/V Retriever. The instrument is an acoustic Doppler current profiler. Credit: J.R. Lacy, USGS The referenced media source is missing and needs to be re-embedded.Delta smelt being displayed on a hand. Credit: National Geographic Society Drivers of Aquatic Habitat
Water export from the San Joaquin Delta is managed by Federal (U.S. Bureau of Reclamation, USBR) and state agencies. These large water projects must be managed both to provide water reliably and to protect species of concern. Fisheries are in decline in the San Joaquin Delta, and several species, including the delta smelt, are threatened or endangered. Major habitat restoration efforts are planned to benefit delta smelt and other native fish species; however, the optimal physical habitat characteristics for these fish are not well understood. The CMHRP collaborates with the USGS Water Resources Mission Area in a USBR-supported study to address critical knowledge gaps about how shallow-water habitats support native fish species. The CMHRP investigates sediment dynamics (i.e., the motion of sediment), and the influence of wind waves on turbidity (the cloudiness of the water)—a habitat characteristic important to delta smelt—in two flooded agricultural tracts in the northern delta with different landscape configurations. Results will help guide ecosystem management actions, including flow manipulations and habitat restoration.
Sources/Usage: Public Domain. Visit Media to see details.Mokelumne River near confluence with the San Joaquin River in the Sacramento-San Joaquin Delta, California, looking downstream, with Cordell Johnson (USGS) and Rachel Allen (USGS) collecting data from R/V Fast Eddy. Credit: J.R. Lacy, USGS - Science
Explore the CMHRP Decadal Strategic Plan, and visit our San Francisco Bay project page
The CMHRP Decadal Science Strategy 2020-2030
This geonarrative constitutes the Decadal Science Strategy of the USGS's Coastal and Marine Hazards and Resources Program for 2020 to 2030.
Sediment Transport in Coastal Environments
Our research goals are to provide the scientific information, knowledge, and tools required to ensure that decisions about land and resource use, management practices, and future development in the coastal zone and adjacent watersheds can be evaluated with a complete understanding of the probable effects on coastal ecosystems and communities, and a full assessment of their vulnerability to natural...