Structural projects are strategies that help manage flooding by building or enhancing public infrastructure along stream corridors. Key elements include:
Projects scattered throughout the basin that provide benefits to affected neighborhoods
Typically led by public agencies
Limited locations are available for structural projects
TWEC technical experts reviewed an inventory of planned capital projects that are already funded to evaluate add-on opportunities. TWEC is also considering potential new structural projects and revenue sources for implementation.
CONVEYANCE: Projects that help move water downstream more quickly.
Promotes neighborhood drainage
Retrofit conveyance in existing neighborhoods
Consider the risk of moving flooding problems downstream
NATURAL RESOURCE ENHANCEMENT: Restoring natural areas like wetlands to absorb flood water.
Requires larger amounts of land relative to expected flood mitigation, though the land may be protected by existing regulations
Focuses on ecosystem health and long-term flood resilience
Intermediate cost compared to other structural projects
STORAGE/DETENTION: Projects that hold flood water in a controlled area and release it slowly.
Water storage is usually held within creek corridors, and is referred to as in-line storage.
Retrofit existing storage in neighborhoods
Explore if new storage level controls may be an option to drain water before large rain events
Improve local habitat as part of storage project
Consider difficulty to maintain fish passage with in-line storage projects
SEDIMENT REMOVAL: Projects that increase the amount of water that can be stored in streams by removing fine sand and mud that builds up over time.
Interrupts the natural process of landscape evolution
Not sustainable but may be temporarily useful for water, or sediment storage
Would require periodic site disturbance with ecological risks
Requires challenging permit processes
Can be costly relative to benefits