landscape runoff as predicted by the hydrologic model, (2) impacts from the proposed Upper St. Johns River (USJR) projects, and (3) predicted sea level rise (SLR).

The hydrodynamic model was run through a comprehensive set of scenarios to evaluate model sensitivity to different forcing functions. The scenario nomenclature follows a keyword pattern of:

Extent of withdrawal   land-use year   Upper basin project status   sea-level rise

where the values for the keywords are:

withdrawal = {Base, Half, Full, FwOR}

land-use = {1995, 2030}

project = {N, P}

sea-level rise = {N, S, H}

The withdrawal conditions are defined as:

•  Base:  Zero surface water withdrawal (existing condition).

•  Half:  50% of the proposed maximum withdrawal rate (77.5 MGD) from the SJR.

•  Full:  100% of the proposed maximum withdrawal rate (155 MGD) from the SJR.

•  FwOR:  Full (155 MGD) SJR withdrawal plus 107 MGD from the Ocklawaha River for a combined 262 MGD withdrawal

The land-use conditions are:

•  1995:   Historic land-use patterns from 1995 data.

•  2030:   Forecast land use patterns for year 2030.

The projects are:

•  N:   No projects: hydrologic effects of USJR projects are neglected.

•  P:   Completed projects: all hydrologic effects of USJR projects are included.

The sea-level rise conditions are:

•  N:   No sea-level rise (i.e., ignore historic trend and use 1995 data).

•  S:   Sea-level rise for 2030 based on historic trend at Mayport (14 cm).

•  H:   Higher estimate of sea-level rise at 2030 (28 cm).

Thus, the scenario name Half1995PN indicates the “Half” withdrawal of 77.5 MGD with historic 1995 land-use, the completed USJR projects, and zero sea-level rise. Table 2-1 shows some of the most commonly used scenarios (and thus represents only a subset of the scenarios used and referred to throughout this report).

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