3.2.1. Selection of Modeled Time Periods

Our modeling approach differentiates between three eras described earlier: a "predevelopment" period, an "instrumented" or "contemporary" period, and an "early development" period that bridges the pre-development and instrumented periods. Tree-ring reconstructions of Central Valley runoff were developed spanning the three time periods. A "long record" reconstruction represents the pre-development period back to WY 903 and a "short record" reconstruction represents the pre-development period back to WY 1640. Both runoff reconstructions cover the early development period spanning WYs 1851–1911; however, a unique Delta outflow and salinity model component was not generated for this period. While some literature is available to characterize the hydrology of this early development period [65–68], associated Delta outflow trends and drivers of change are poorly understood. In light of this uncertainty, we assumed that the early development period was adequately represented by pre-development relationships between runoff, Delta outflow and salinity.
