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Mother Nature’s Message
for Sea Level Rise, Floods and Bluff Erosion
Don Mosier | Rimini Road

The City of Del Mar has received two grants from the California Coastal Commission to evaluate the risks posed by sea level rise, and how the city can amend its Local Coastal Plan to adapt to higher sea levels and more frequent extreme storm events triggered by global warming. The Sea Level Rise Stakeholder Technical Advisory Committee has met frequently to respond to technical data provided by our Environmental Science Associateconsultant team, and the risk assessment document is available on the city website at: (www.delmar.ca.us/DocumentCenter/View/2455)

A draft report on adaptation strategies was released last September by ESA, Environmental Science Associates (the consultant hired by the city). Nevertheless, policy decisions by the city are waiting on clearer guidance from the Coastal Commission and state policy guidelines. Del Mar is unique in that it faces threats to the beach, floods from the San Dieguito River, and bluff erosion that is already threatening the railway tracks. Adaptation strategies will be triggered by the amount of sea level rise, with current projections shown in Table 1.

TABLE: SEA LEVEL RISE (SLR) PROJECTIONS

High priority adaption measures highlighted in the draft document include:

• Relocating the Fire Station
• Relocating the Public Works Yard
• Flood proofing the 21st Street sewer lift station

Bluff erosion will require moving the tracks off the bluff within 20 years. This is a project that cannot be delayed, and if more recent projections of accelerating sea level rise prove correct, then action will be required before 2030. This project needs to begin the planning stages now.

More extreme weather events and sea level rise will increase flooding along the San Dieguito River and the northern beach district built in the floodplain. A one-foot rise in sea level creates a 100-foot increase in beach run-up. Imagine a winter storm that coincides with high tide and 4 inches of rain, what used to be called a 100-year storm. These events will become more common, and will soon be a 20-year storm. Adaptation will eventually mean moving buildings, raising bridges, and retreating from the growing power of Mother Nature. Difficult policy decisions lie ahead, and if we don’t slow down global warming, they will need to be made sooner rather than later.

 

 

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