Newport Beach Presentation on Sea Level Rise

Newport Beach Presentation on Sea Level Rise

Newport Beach’s Speakout Newport group held an excellent presentation of the city’s response to sea level rise. The Newport Bay Balboa Island was built on dredged-up sand and confined by metal plates, about 100 years ago. Newport is also on the delta and bay of the San Diego Creek, stretching into the back bay. The Newport Bay harbor is separated from the Pacific Ocean by the narrow, few-block-wide, Newport Peninsula. This is a standard target for sea level rise, high tides, and storm surge, especially if matched by down-River storm runoff.

There was a Tidelands Management Committee, which decided to raise the sea wall around Balboa Island.  This committee was abolished, however, in Jan. 2017, and its task taken over by the Harbor Commission.

The speakers were:

James Campbell, the development land use planner;

Robert Stein, Assistant City Engineer;

Brett Sander’s, Prof. Of Civil and Environmental Engineering, UC Irvine, and developer of FloodRISE; and

Jochen Shubert, Post Doctoral Researcher in the Computational Hydraulics Lab, Dept. of Civil and Environmental Engineering, UC Irvine.

James Campbell showed projected sea level rise curves, which at the year 2100 either gave 1.5 feet, 3.0 feet, or 4.5 feet. The difference, elucidated by my question in the question session, depends on the response of the nations of the world to climate change.

Actions are subject to California Coastal Act regulations. Cities set up a Local Coastal Program and obtain permits for their actions. They have to monitor their use. Cities need a short and long term adaptation strategy. These are given to the Coastal Commission.

The maintenance of Balboa Island and Bay sea walls has been revised from 9 feet to now 10 feet above mean sea level. There is also floor elevation. Sand from the Santa Ana river can be used to replace beach erosion, and to protect the land. Bulkheads and building pads will be raised.

In order to not overspend or over-correct, the city uses the lowest range of projections for 75 years. The strengthening would be subject to flooding in 75 years. The projections used were from 1.5 feet to 3.0 feet.

The Balboa Island wall cannot have any missing segments. There is a 9 inch rise for the Balboa Island seawall being installed, along with an extra step to get over the wall.  The walkway may also need to be raised. Homeowners on the walkway may lose some view from the raised wall. The city is also going to compel improvements to private property.

The city does not want to overreact too soon. They also don’t want to increase future costs or risks. The uncertainty may or may not decrease over time. (He didn’t explain this, but I will try. When we know how much we are mitigating greenhouse gases, a lot of uncertainty will be removed. But there is still the possibility of an extra 2-3 feet rise from Greenland and Antarctica melting. However, Earth System Sciences may also reduce uncertainties in this melting.)

Bob Stein reported that the last big storm was 20 years ago. You can have raised sea level due to wind, boats, and waves. The 9 inch wall increase should insure Balboa Island for 10-15 years. By 2100, there can be 2-3 feet of rise. The Coastal Commission envisions a possible 66 inch or 5.5 feet of sea level rise. (With the estimate of 3.3 feet worldwide mean sea level rise, plus 2.2 feet speculative from Greenland and Antarctica would give 5.5 feet.)

There are 18 linear miles of bay to protect. The city will entertain no retreat. To protect the beach side of the peninsula, they will use beach berms. They will raise the Fun Zone, and the streets of the Peninsula. They need 14 foot berms, and they would be too high if the streets were not raised.

Ground water will rise under Balboa Island through seepage, and they will have to revise the storm drain system. They close the valves in high tides to prevent sea water from inflowing. The Peninsula may also need this.

The harbor sea walls are 60 years old. The Balboa Island sea walls are 80-90 years old. The city will have to replace the sea walls at a cost of $500 million. Groundwater protection will cost $100-200 million. Other things will cost $150 million. The upper Newport Bay will cost $50 million. Over 50 or 100 years the protection will cost a billion dollars.

Brett Sanders and UCI FloodRISE

There is $100 billion of infrastructure that would be exposed by 1.4 meters (4.6 feet) of sea level rise in California. 67% of California’s beaches will be eroded by the year 2100. Nationally, 2017 set a record of $300 billion in flood damages. There were 15 different billion dollar events. This was only matched by Katrina and New Orleans in 2005. Some places have a chronic high-tide problem.

Level maps don’t account for rainfall and runoff in a storm. So FloodRISE was funded by the NSF, to include drainage and waves in determining flood distribution. FloodRISE works with Google Earth. It has been applied to Newport Beach.  It was checked on a household feedback level, and with stakeholders. It has an online portal and there is also training available. There is a need to iterate it with users.

For preventing flooding, resilience and zoning are the best method. The best nature-based solution is beaches. This involves beach nourishing and grade raising. Salt water marshes are good buffers. A good source of sediments is needed for the beaches. There also need to be a quicker permitting process for projects. In 2005, local flooding was caused by a 7.7 foot high tide.

Jochen Shubert demonstrated the use of FloodRISE for 2035 and 2050. For 2050 he used 1.4 feet for the projected rise. FloodRISE can add photos to its maps. It can also show landmarks. It can mark properties which have flood evasions built in. It can calculate the probability of 100 year events, and include rainfall and stream flow. It can also show how deep the flooding is at various locations.

FloodRISE is on the website: FloodRISE.uci.edu

In the Question period, it was pointed out that floors had to be raised to a 9 foot height, and the approved height of a building could be raised the same amount needed to accomplish that.

(As an observer, who doesn’t even live in Newport Beach, I probably shouldn’t comment, but that has never stopped me. The city is a mix of those who lived there a long time and may exist on retirement income, along with younger professionals who could afford to buy million dollar houses. How do you charge these segments with care to not send anyone off the island? One way is to charge proportional to their property taxes. Long time residents pay lower property taxes.  The method of paying for the protection was not mentioned in the talks.)

(There also was no mention of actions to prevent climate change, which causes sea level rise, except by one commenter, who was applauded by many.)

(Campbell showed that China now emitted more greenhouse gases than the US, and India was catching up with the US. However, he forgot to mention that both countries had four times the population of the US.)