ER Alternative Development Strategy

The ER measures were assembled into alternatives with a systematic combination of management measures based upon specific planning objectives to narrow the possible solutions

4.2.3.6.1 Identification of Lines of Defense and Ecosystem Restoration

The formulation strategy is based on the concept that natural landforms provide lines of defense against coastal storms. The concept of lines of defense is also related to

protection of coastal ecosystems and human infrastructure from storm damage caused

by hurricanes and tropical storms coming ashore from the Gulf. The series of barriers provided first by the barrier islands, then by living shorelines, and finally coastal marshes can reduce the physical impacts of storm surges and winds which enter the bays. This combination of lines of defense and ER is intended to provide redundant levels of protection and restoration for both humans and Texas coastal ecosystems.

1st Line of Defense and Ecosystem Restoration – Barrier Systems

Barrier islands, shorelines and headlands, as well as tidal inlets form the first line of defense for the nine major estuarine bays and the residential, industrial, and

recreational structures therein. They are the boundary between the Gulf and estuarine and the terrestrial ecosystems. These features include barrier beach, dune, back marsh, and shallow open- water areas along the inland side of barrier islands. Coastal barriers also provide habitat for various marine, estuarine, and terrestrial organisms as well as stopover habitat for migrating neotropic birds. Coastal barrier systems provide

protection to the wetlands, bays, and estuaries located behind the barrier systems.

These features influence tidal prism, limit storm surge heights, retard saltwater intrusion, and limit mechanical erosion by reducing wave energy at the margins of coastal

wetlands. Coastal barrier systems and other features of the coastal landscape (e.g., shoals, marshes, and forested wetlands) can provide a significant and potentially

sustainable buffer from wind-wave action and storm surge generated by tropical storms and hurricanes.

2nd Line of Defense and Ecosystem Restoration – Estuarine Bay System

Bay shorelines, inlets, and bordering estuarine marshes form the second line of defense and ER. As the barrier systems are eroded, fragmented, and lost, the tidal prism seeks to re- establish dynamic equilibrium between the higher energy Gulf forces moving tidal waters faster and higher into the upper parts of the estuary thereby subjecting bay shorelines and estuarine wetlands to greater Gulf forces of wind and wave erosion and higher salinities. These cumulative changes can cause estuarine marsh loss and shoreline erosion. Estuaries provide habitat for ecologically, commercially and recreationally important fish and wildlife. Estuaries are particularly important nursery habitat for many organisms with early life stages depending on salinities below Gulf salinities. Estuarine shorelines also provide important habitat for migrating neotropic birds.

Associated with estuarine bay systems are adjacent bird rookery islands, oyster reefs, and submerged vegetation beds. Each of these habitat features are typically isolated and relatively small features, as in the case of bird rookery islands. Despite this, when considered from a cumulative perspective, the combination of these features within an estuarine bay system can have significant local, regional, and especially important to the NER requirements for the study, national importance. In addition, strategic

placement and numbers of bird rookery islands, oyster reefs, submerged vegetation beds and living shorelines can also function as terraces to slow down waves and sediments, reduce fetch and create EFH.

3rd Line of Defense and Ecosystem Restoration – Bayhead Deltas

The third line of defense and ER involves conserving, restoring, and protecting bayhead

deltas. Managing freshwater inflows to optimize salinity, sediment, and nutrient regimes helps sustain deltas and their associated habitats. Developing sediment management strategies would maximize delta accretion and sustain important wetland habitats provided by healthy deltas. Opportunities to manage hydrologic connectivity could also help benefit delta wetlands. The land and wetland habitat provided by deltas further protects human infrastructure and estuarine ecosystems.

Similar to barrier and estuarine bay systems, there are adjacent bird rookery islands, reefs, and SAV which provide benefits similar to those previously described for barrier systems and bay systems.

Six ER alternatives were developed using the formulation strategies. Initial formulation considered two scales for the measures to reduce impacts of RSLR scenarios.

Following policy review, the Scale 2 measures that proposed out-year construction for measures G- 28, B-12, CA-5, and M-8 were found to be policy non-compliant and removed from the Recommended Plan. Table 18 provides a summary of the measures in the alternatives. Table 19 presents the list and title of the alternatives. Figure 23 through Figure 28 illustrate the alternatives as a combination of the features.

Table 18 - ER Measures by Alternative

Alt. G5 G28-1 G28-2 B2 B12-1 B12-2 CA5-1 CA5-2 CA6 M8-1 M8-2 SP1 W3

1-1 • • • • • • • • •

1-2 • • • • • • • • •

2-1 • • • • •

2-2 • • • • •

3-1 • • • •

3-2 • • • •

4-1 • • • • • •

4-2 • • • • • •

5-1 • • • •

5-2 • • • •

6-1 • • • • •

6-2 • • • • •

Table 19 - List of Fully Formed ER Alternatives

Alternative/Scale Strategy/Description

No-Action No-Action

Alternative 1-1 Coastwide All-Inclusive Restoration Alternative (Scale 1) Alternative 1-2 Coastwide All-Inclusive Restoration Alternative (Scale 2) Alternative 2-1 Coastwide Restoration of Critical Geomorphic or Landscape

Features (Scale 1)

Alternative 2-2 Coastwide Restoration of Critical Geomorphic or Landscape Features (Scale 2)

Alternative 3-1 Coastwide Barrier System Restoration (Scale 1) Alternative 3-2 Coastwide Barrier System Restoration (Scale 2) Alternative 4-1 Coastwide Bay System Restoration (Scale 1) Alternative 4-2 Coastwide Bay System Restoration (Scale 2)

Alternative 5-1 Coastwide ER Contributing to Infrastructure Risk Reduction (Scale 1)

Alternative 5-2 Coastwide ER Contributing to Infrastructure Risk Reduction (Scale 2)

Alternative 6-1 Top Performers (Scale 1) Alternative 6-2 Top Performers (Scale 2)

Figure 23 - ER Alternative 1, Scale 2

Figure 24 - ER Alternative 2, Scale 2

Figure 25 - ER Alternative 3, Scale 2

Figure 26 – ER Alternative 4, Scale 2

Figure 27 – ER Alternative 5, Scale 2

Figure 28 - ER Alternative 6, Scale 2