Barnegat Bay & Surf City Grid Hydrodynamics
Active Coastal Flood Inundation
Incident Observation Grounding: Juvenile sandbar sharks (Carcharhinus plumbeus) and smooth dogfish inhabit Barnegat Bay shallow nurseries during late summer and autumn. When astronomical high tide pairs with a 4–5 ft coastal nor'easter surge, saltwater submerges bulkhead bulkheads and drains backward up bulkheaded street storm drains, turning Surf City's bulkheaded canal streets into temporary marine estuaries.
🌊 Why Sharks Enter Flooded NJ Streets
Barrier island geography (such as Long Beach Island, NJ, where Surf City is situated) features an ocean beach on the east and shallow protected lagoon bays on the west. During coastal storms, easterly winds push Atlantic waters into inlets, trapping millions of gallons in Barnegat Bay (the "bathtub effect").
Because the street elevation near back-bay lagoons is often only 2.5 to 3.5 ft above NAVD88, a +4.5 ft surge drives marine predators directly across bulkheads and up curb gutters following schools of baitfish (menhaden and silversides).
⚠️ Ebb Tide Stranding Hydrodynamics
The primary mortality risk for displaced marine wildlife is not the flood itself, but the rapid surge retreat during ebb tide:
- Velocity Differential: As back-bay surge ebbs, water drains faster through canal inlets than across paved roadways with reverse curb pitch.
- Trapping Depressions: Potholes, road crowns, and flooded garage slabs leave isolated pools under 8 inches deep, trapping sharks unable to swim against retreating currents.
- Salinity & Oxygen Depletion: Urban runoff and stagnant street water rapidly drop dissolved oxygen levels within hours.
🛡️ Municipal Barrier & Check Valve Engineering
This simulator models real coastal adaptation interventions:
- Tide-Flex Backflow Valves: Rubber duckbill check-valves installed in storm drain outfalls prevent back-bay surge from filling streets via gravity while still allowing upland rainwater to discharge under pressure.
- Temporary Deployable Coffer Dams: Sandbags and inflatable Tiger Dams deployed across bulkhead street-ends prevent surface overflow into residential avenues.