The San Francisco Bay Delta Model

Framework of CASCaDE II

The following presents a brief introduction of the Cascade project. More detailed infromation can be found here.

Introduction

 In recent years, two guiding principles have been established regarding the future management of the Sacramento-San Joaquin Delta. First, Governor Schwarzenegger’s Blue Ribbon Task force recommended that “the Delta ecosystem and a reliable water supply for California are the primary, co-equal goals for sustainable management of the Delta” [Isenberg et. al. 20081] , and this principle recently became state law. Second, fundamental changes in the external forcings (e.g. climate) and physical configuration of the Delta are inevitable [Healey et. al. 20082, Lund et. al. 20083]

These guiding principles lead to the fundamental question we propose to address: How will future changes in physical configuration and climate affect water quality, ecosystem processes, and key species in the Delta?

In particular, we propose to test the hypothesis that: Climate induced changes in hydrology, sea level, and local meteorology, combined with new water conveyance structures or increased numbers of flooded islands, will impact water transport and water quality (e.g. salinity, temperature, and turbidity) in the Delta. These changes will further influence ecological processes and key species (e.g. primary productivity, distributions and effects of invasive bivalves, marsh sustainability, contaminant dynamics, and success of native and alien fish populations).

Need for an integrated and uniform modeling approach

The movement of water is a primary control on Delta water quality (e.g. salinity, water temperature, contaminants, turbidity) and ecology (e.g. macro-zoobethos, plankton, bivalves and fish), as well as the interactions between water quality and ecosystem components (e.g. the availability of phytoplankton as a food source to benthic bivalves, or the co-occurrence of favorable temperature and turbidity conditions for fish). These physical-water quality-ecological interactions are expected to evolve as a result of climate change via shifts in magnitude and timing of river inflows at the upstream boundaries, changes in sea level at the downstream boundary, and changes in atmospheric forcing (e.g. heating, wind) from above. In addition, future planned (e.g. water conveyance) and unplanned (e.g. earthquake induced levee failure) structural changes to the Delta have the potential to abruptly transform water movements and, consequently, water quality and ecosystem function. The large implications of hydrodynamics for management of ecosystem processes and water supply, therefore, require a high quality representation of Delta hydrodynamics and its water quality and ecosystem linkages. The Bay-Delta model will be applied to evaluate ecosystem and geomorphic changes resulting from different scenarios of climate and structural change on the Bay-Delta System.

References

  • Isenberg et. al. 2008. Blue Ribbon Task Force Delta Vision: Our Vision for the California Delta. State of California Resources Agency. Sacramento, California]
  • Healey et. al. 2008. Introduction: New Perspectives on Science and Policy in the Bay-Delta. The State of the Bay-Delta Science. p. 1-18.
  • Lund et. al. 2008. Comparing Futures for the Sacramento-San Joaquin Delta. Public Policy Institute of California. 147 pp.].