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  • Title

    Mapping the adaptation governance network of the Delta

    Lead University of California - Davis [UC Davis]
    Description Climate adaptation in the San Joaquin-Sacramento Delta involves multiple agencies, communities, venues, projects, and issues. Understanding how learning and cooperation occurs within this complex governance network is critical for carrying out effective and equitable adaptation. The main objective of this project is to understand how and why human communities (e.g., community organizations, local governments, and Tribal entities) are engaged in this governance system and the drivers of learning and cooperation for climate adaptation. To accomplish this, we will map the network of current adaptation actors, institutions, and actions, assess their engagement in the governance system, and conduct in-depth case studies on existing adaptation projects in the San Joaquin – Sacramento Delta.
    Science topics Climate change
    Updated February 27, 2025
  • Title

    Examining the relationship between Longfin Smelt and flow in the San Francisco Bay Delta

    Lead University of California - Berkeley [UC Berkeley]
    Description The number of longfin smelt in the San Francisco Estuary has been in decline for the past several decades. While decreased freshwater flow reaching the estuary has been identified as a contributing factor, the relationship between flow and smelt populations has proven complex and appears to be changing over time. This study examined how water flow affects longfin smelt populations across different habitats in the San Francisco Estuary, analyzing decades of monitoring data from state and federal agencies. The research explored both where smelt live in the estuary and how their populations change over time in response to varying water flows. The findings show that more freshwater flow generally helps smelt populations, especially young fish in shallow waters. However, this beneficial effect appears to be weakening over time in some areas, particularly in open waters away from the shore. This suggests that smelt may be adapting to changing conditions by moving to different parts of the estuary. To help protect this threatened species, conservation efforts may need to focus on both restoring natural water flows and improving habitat conditions throughout the estuary.
    Science topics Fish, Flows, Longfin Smelt, Zooplankton
    Updated February 27, 2025
  • Title

    Assessing sea-level rise and flooding changes in the Sacramento/San Joaquin Delta using historical water-level records

    Lead California State University [CSU]
    Description The project aims to recover, digitize, and analyze more than 1300 station years of ‘lost-and-forgotten’ water level records collected from 1857 to 1982 in the Sacramento-San Joaquin Delta. These measurements, augmented by modern data, will improve our understanding of tidal, flood, and sea level trends in the system. By determining ‘hotspots’ of habitat and flood risk sensitivity, the results may be used to better focus future scientific and management priorities, to protect the environment, manage flood risk, and enhance community resilience to climate change
    Science topics Backwater, Climate change, Environmental drivers, Estuaries, Land elevation, Levees, Outflow, Sea level rise, Stage, Subsidence, Surface water / flow, Tides, Velocity, Vessels and shipping channels, Water, Wind
    Updated October 10, 2023
  • Title

    Analysis of Delta Salinity during Extended Drought – Pilot Project

    Lead California Department of Water Resource [DWR]
    Description Managing California water operations for multiple priorities under long term drought conditions is becoming an increasing challenge which is compounded by potential sea level rise. This project is a pilot exercise to demonstrate the utility of hydrodynamic and salinity transport models in to understand options for salinity management under extended drought combined with climate change and sea level rise. The project will also consider how to make model outputs available and relevant to other modeling and environmental management decision making efforts. The full range of potential sea level rise, restoration and operational actions is extensive, involving many potential combinations of individual actions. Therefore, it is difficult to fully explore potential actions with high resolution multi-dimensional models. The proposed approach is to use high resolution multi-dimensional flow and transport models to evaluate changes in transport in the Delta under sea level rise, restoration, and operational scenarios. The predicted changes to salinity for a given scenario will inform operations modeling in CALSIM through re-calibration of an ANN to approximately account for the changed salinity response of the estuary. Operations modeling incorporating the revised ANN will then estimate Delta inflows and overall water cost to meet Delta standards for the scenario. “Round-trip” modeling will be performed using the detailed Delta models to verify that the predicted hydrologic inputs allow appropriate compliance with water quality standards and will provide other metrics related to Delta transport.
    Science topics Conductivity, Drought, Landscape change, Restoration planning, Sea level rise, Water operations / exports
    Updated June 14, 2024
  • Title

    Carbon Biogeochemical Cycling in Tidal Wetlands: Exploring Lateral Carbon Exchange and Sequestration Potential

    Lead University of California - Berkeley [UC Berkeley]
    Description Tidal wetlands, at the interface of land and ocean, play a critical role in carbon biogeochemical cycling and have the potential to provide major feedback to the Earth system through greenhouse gas exchange and long-term carbon sequestration. However, the efficiency of carbon sequestration in tidal systems relies on both vertical carbon exchange with the atmosphere and lateral tidal exchange with adjacent water bodies. Unfortunately, the importance of hydrologic carbon fluxes has been largely overlooked, leaving a crucial aspect of coastal wetland net carbon balance unaddressed. We employed an integrated approach to quantify vertical and lateral carbon exchange and studied their dynamics, combining eddy covariance flux measurements with on-site water quality and tidal discharge measurements, as well as manual 24h surface water samplings. Our measurements were conducted in a recently restored tidal freshwater marsh in the Sacramento-San Joaquin Delta, CA, that stands out in global networks like FLUXNET and Ameriflux owing to its impressive net ecosystem exchange of -850 g C m-2 yr-1. Using wavelet decomposition, we examined the variability of carbon exchange (CO2 and CH4) across different timescales. Through information theory and mutual information analysis, we assessed the factors influencing both vertical and lateral exchanges. Our preliminary findings suggest that variability in carbon exchange is largest at the diel scale, with plant gross primary productivity and tidal fluctuations in depth having the most significant interactions with CO2 and CH4 fluxes, respectively. Furthermore, our tidal cycle samplings revealed that dissolved inorganic carbon dominates the fraction of lateral carbon loss, accounting for approximately 80% of the export. Remarkably, similarities existed between the values for net lateral carbon export and ecosystem respiration, signifying that the dissolved, terrestrial-to-ocean carbon flux could represent one of the primary fates of the fixed carbon in this tidal ecosystem. These large dissolved inorganic carbon fluxes and their chemical speciation, are important to consider when estimating the climate mitigation potential of restored tidal wetlands.
    Science topics Carbon, Carbon storage, Greenhouse gas GHG
    Updated January 30, 2024