Modeling Restoration Outcomes for the Everglades Ridge-Slough Landscape Jay Choi Jud Harvey Noah Schmadel

Transcription

1 Modeling Restoration Outcomes for the Everglades Ridge-Slough Landscape Jay Choi Jud Harvey Noah Schmadel

2 Factors Affecting Restoration Success Hydrologic Conditions: Maintain water depth and flow for vegetation communities and ecological processes Degraded Functionalities of the Landscape: Deep water slough (60%) between ridges supports production and diverse ecosystem Restored

3 Everglades Restoration Options Option A = No Action Existing Conditions Baseline (ECB) (SERES Report, 2015 Everglades Foundation) Goal Forecast outcomes of 4 restoration options in different sub-basins

4 Everglades Restoration Options A B C D E Options Existing Conditions Baseline (ECB) Comprehensive Everglades Restoration Plan (CERP) Partial Restoration (PR) "CERP light" Expanded Storage and Decomp (ESD) Maximum Storage and Decomp (MSD) Water Storage (acre-feet/yr) % Predrainage flows % Reduction of Internal Barriers to Sheet Flow miles of levees 3.0M M M M (SERES Report, 2015, Everglades Foundation) Our Approach: 1. Existing Hydrologic Simulations From (SFWMD, 2008) 2. Functionality Metrics of the Landscape Forecast System-Wide Restoration Outcomes

5 Metrics of Ridge-Slough Functionality 1. Ridge-slough microtopography Good: >20 cm difference At Risk: cm difference Poor: <10 cm difference Wu et al., 2006 Ecological Complexity Nungesser, 2011 Wetlands Ecology and Management Watts et al., 2010 Ecosystems (Watts et al., 2010) Choi and Harvey, 2016, Restoration Ecology)

6 Metrics of Ridge-Slough Functionality 1. Ridge-slough microtopography 2. Vegetation (ridge) coverage Good: <50 % At Risk: % Poor: >65 % (Wu et al., 2006) Choi and Harvey, 2016, Restoration Ecology)

7 Metrics of Ridge-Slough Functionality 1. Ridge-slough microtopography 2. Vegetation (ridge) coverage 3. Directional Connectivity Index (DCI) Good: >0.6 At Risk: Poor: <0.4 DCI = 0 DCI = 1 (Larsen et al., 2012) Choi and Harvey, 2016, Restoration Ecology)

8 Metrics of Ridge-Slough Functionality 1. Ridge-slough microtopography 2. Vegetation (ridge) coverage 3. Directional Connectivity Index (DCI) DCI = 0 DCI = 1 Choi and Harvey, 2016, Restoration Ecology)

9 Target Hydrologic Conditions 1. Water Depth in Sloughs (cm) Dry Season Wet Season Good: At Risk: or Poor: <5 <35 or >85 2. Hydroperiod (# days sloughs are flowing) Good: >350 At Risk: Poor: < Flow velocity (cm/s) Good: >1.0 At Risk: Poor: < Angle between flow and slough orientation (degree) Good: <20 At Risk: Poor: >35 Choi and Harvey, 2016, Restoration Ecology)

10 Flattening of Ridge-Slough Microtopography (Present-Day) Variation between ridge and slough landscape Slough Ridge Key Good: >20 cm At Risk: cm Poor: <10 cm Metric Microtopographic difference (cm) North Central Sub-basin South WCA-3B ENP (Choi and Harvey, 2016, Restoration Ecology)

11 Proliferation of Vegetation (Present-Day Sawgrass) Key Good: <50% At Risk: 50-65% Poor: >65% Conserved Metric Vegetation Coverage (%) Degraded North Central Sub-basin South WCA-3B ENP (Choi and Harvey, 2016, Restoration Ecology)

12 Lost Directional Connectivity of Landscape (Present-Day) Key Good: >0.6 At Risk: Poor: <0.4 Conserved Degraded (Larsen et al., 2012) Metric North Central Sub-basin South WCA-3B ENP DCI (Choi and Harvey, 2016, Restoration Ecology)

13 Summary of Present-Day Landscape Functionality Metric Microtopographic difference (cm) Vegetation Coverage (%) North Central Sub-basin South WCA-3B ENP DCI Lost ridge and slough landscape functionality at North and WCA-3B (Choi and Harvey, 2016, Restoration Ecology)

14 Predicted Water Depth During Dry Season No action Moderate Aggressive Water depth in sloughs (cm) Options North Central South WCA-3B ENP ECB PR CERP ESD MSD Restoration actions cannot improve the water depth at North during the dry season Key Good: cm At Risk: 5-15 cm Poor: <5 cm (Choi and Harvey, 2016, Restoration Ecology)

15 Predicted Water Depth During Wet Season No action Moderate Aggressive Water depth in sloughs (cm) Options North Central South WCA-3B ENP ECB PR CERP ESD MSD Improvement at North, but only for most aggressive option Aggressive action may put WCA-3B at risk Key Good: cm At Risk: or cm Poor: <35 or >85 cm (Choi and Harvey, 2016, Restoration Ecology)

16 Predicted Hydroperiod No action Moderate Aggressive # days sloughs are flowing Options North Central South WCA-3B ENP ECB PR CERP ESD MSD Restoration actions cannot improve the hydroperiod at North Key Good: >350 d At Risk: d Poor: <340 d (Choi and Harvey, 2016, Restoration Ecology)

17 (Choi and Harvey, 2016, Restoration Ecology) Predicted Flow Speed and Direction Options North Flow Speed (cm/s) Central South WCA-3B ENP ECB PR CERP ESD MSD Good: >1.0 At Risk: Poor: <0.4 Options Angle between flow direction and slough orientation (degree) North Central South WCA-3B ENP ECB PR CERP ESD MSD Good: <20 At Risk: Poor: >35

18 Forecasted (36 y) Restoration Outcome No action Moderate Aggressive Options North Central South WCA-3B ENP ECB Poor At Risk Poor Poor At Risk PR Poor At Risk Good Poor Good CERP Poor At Risk Good Poor Good ESD Poor At Risk Good Poor Good MSD Poor At Risk Good Poor Good Failed to achieve target hydrologic conditions at North and WCA-3B (Choi and Harvey, 2016, Restoration Ecology)

19 Conclusions Not all sub-basins benefit equally from restoration. None of the restoration options are likely to improve North and WCA-3B functionality. All restoration options are likely to improve the hydrologic conditions at Central, South, and ENP. For most cases, moderate and aggressive restoration options predicted very similar outcomes for landscape conditions. Present-day extent of ridge-slough microtopographic difference appears to be the best single predictor of restoration success.