Target Questions

Target Questions for the Sacramento-San Joaquin Delta Historical Ecology Study

These target questions have been developed through conversations with project partners and local stakeholders, review of current scientific research questions in the Delta, and previous experience in systems with similar concerns. We expect questions will continue to evolve through future conversations with technical advisors and project partners.

This study aims to document the pre-modification habitat characteristics of the Delta at a spatial scale and level of detail relevant to restoration planning and conservation efforts. The target questions provide the guiding framework from which to assemble key scientific information towards this goal.

It will likely not be possible to answer all questions with the same certainty or thoroughness. Consequently, technical questions will be re-evaluated after data collection and compilation to decide which are worth pursuing or should be de-emphasized. This process shall include review by technical advisors to reach consensus on the approach and associated level of certainty with which questions can be answered. Key criteria for this re-evaluation shall include consideration of data availability and cost, as well as relevance to Delta restoration and conservation planning.

The fundamental goal of the Delta Historical Ecology Study is to document, to the extent possible, the pre-modification extent and character of different wetland, riparian, and terrestrial ecotonal habitats. This description of spatial patterns will help us better understand ecosystem support functions and controlling physical processes within the landscape context. Such information will
provide a basis for identifying target locations and physical conditions necessary to restore functional habitat mosaics within the projected future Delta landscape that are capable of providing multiple ecological services.

Channel Geometry and Hydrodynamics

Extent and Density
What was the density of tidal channels in the Delta? Did that vary significantly along ecological gradients?
Were there large "undrained" occasionally tidal areas with no channel network -- such as along the eastern margin?
Were the channels along this edge seasonal?
Were they dominated by fluvial or tidal processes?

Order, size and sinuosity
What was the historical extent of channels of different sizes?
How wide were second and third order channels?
How does this compare to more saline systems?
How much marsh area was associated with 2nd, 3rd, and 4th order systems?
What was channel sinuosity relative to location within the Delta (e.g. relative to tidal and salinity gradient)?

Connectivity
What was the extent of "dead-end" versus connected channels and how did that (and associated residence time) vary across the Delta?

Tidal and salinity gradient
What was the extent of tidal influence upstream along main channels?
Can we define historical X2?

Tidal Marsh

Tidal marsh extent
What were the historical boundaries of tidal marsh within the Delta?
What was the character and extent of the transition between fully tidal, occasionally tidal, and nontidal marsh habitats?
What was the extent of brackish versus freshwater tidal marsh?

Elevation...