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Home My WebLink About20210511_Coastal Hazards_05-03-2021 P M A C O N S U L T I N G , I N C . CONSULTING STRUCTURAL ENGINEERS 28161 Casitas Ct. PH. (714) 717-7542 Laguna Niguel, CA 92677 e-mail: consulting@pma-bg.com May 3, 2021 Masum Azizi Azizi Architects, Inc. 1601 Dove Street, Suite 255 Newport Beach, CA 92660 RE: COASTAL HAZARDS ANALYSIS REPORT FOR CDP 114 East Oceanfront City of Newport Beach, County of Orange PMA Job #40121 Dear Mr. Azizi, PMA Consulting, Inc. is pleased to provide this report regarding Coastal Hazards Analysis in for the proposed development at the subject site. The site is adjacent to Pacific Ocean; thus, it may be subject to Coastal Hazards such as, flooding, wave runup, and erosion. This study investigates the potential for the aforementioned hazards to impact the proposed development on the site over the next 75 years and addresses compliance with Coastal Hazards Analysis Report requirements and standards of NBMC Section 21.30.15.E.2. STATEMENT OF THE PREPARER’S QUALIFICATIONS Plamen Petrov, P.E., the preparer of the Coastal Hazards Analysis Report on this project, holds a Master of Science in Structural Engineering from University of Architecture, Structural Engineering & Geodesy of Sofia, Bulgaria, and is a Licensed Civil Engineer by the State of California Certificate No. C66947. For the last 21 years of his professional career, he has been actively involved in the design and entitlement of many Waterfront Developments such as custom homes, seawalls, piers, platforms, floating docks and marinas. A great number of Coastal Hazards Analysis Reports prepared by him have been reviewed and accepted/approved by California Coastal Commission. All the above being said, Plamen Petrov, P.E. shall be considered a qualified preparer for the Coastal Hazards Analysis Report on this project. Requirements in Appendix A for Step 1: Establish the project sea level rise range for the proposed project’s planning horizon (life of project) using the current best available science. The State of California Sea-Level Rise Guidance 2018 update developed by the Ocean Protection Council in close coordination with Policy Advisory Committee with representation 1PA2021-112 from California Natural Resources Agency, the Governor’s Office of Planning and Research, and the California Energy Commission provides a bold, science-based methodology for state and local governments to analyze and assess the risks associated with sea-level rise, and to incorporate Sea- Level Rise into their planning, permitting, and investment decisions, and it is considered the current best available science. As reflected in the clouded area of the enclosed Table 28, based upon direct interpolation of the data for High emissions 2090 & 2100 and Medium-High Risk Aversion, over the project’s planning horizon of 75 years, the estimated Sea-Level Rise (SLR) for year 2096 shall be approximately 6.00’, which is the Sea- Level Rise for the proposed project. Based on the highest high tide of +7.90’MLLW (7.70’NAVD88) recorded in the project area, the above established Sea-Level Rise will account for bay water level of +13.70’NAVD88. Instead of chasing a moving target for minimum top of bulkhead elevations every year, as of March 23, 2021, Planning Department of City of Newport Beach has adopted new standard establishing a minimum top of bulkhead/seawall elevation based on 5-year increments, reflected in Table 2 below from City of Newport Beach Waterfront Projects Guidelines and Standards Harbor Design Criteria for Commercial and Residential Facilities 2021 Edition. Requirements in Appendix A for Step 2: Determine how physical impacts from sea level rise may constrain the project site, including erosion, structural and geologic stability, flooding, and inundation. According to the enclosed Grading Plan C-2, 1st Finished Floor elevation of the proposed development is at +12.70’ NAVD88=+12.90’MLLW which follows the Base Flood Elevation established for the area. Based on the SLR established in Step 1 above, 1st floor of the proposed structure will remain above High Tide sea level approximately until year of 2074, based on Medium-High Risk Aversion, and it will remain above High Tide sea level for the next more than 75 years Based on Low Risk Aversion. As we well know, majority of the public streets in Newport Bay area are currently at much lower elevations than the subject site and they will flood due to SLR way before the development on this site becomes subject to flooding. 2 Table No. 2 Year Structure Adopted NB Standard Design for Adaptability Permitted Elevation {feet) 1 Elevation {feet) 2 NAVD88 MLLW NAVD88 MLLW 2020 10.7 10.9 13.7 13.9 2021 -2025 10.9 11.1 14.4 14.6 2026-2030 11.0 11.1 14.6 14.8 2031 -2035 11.0 11.2 14.8 15.0 1. Derived using the Upper Limit of the Low Risk Aversion probabilistic sea level rise protecJion scenario for lhe Los Angeles tidal gauge, estimated 75 years into the future based on lhe State of California Sea Level Rise Guidance, 2018 Update. This scenario accounts for the upper range of what is ''likely to occur" with approximately an 83 percent probability that sea level rise ftdls below the elevations shown. 2. Derived using the Medium-High Risk Aversion probabilistic sea level rise protection scenario for the Los Angeles tidal gauge, estimated 7 5 years into the future based on the State of California Sea Level Rise Guidance, 2018 Update. This scenario accounts for increased sea level with approximately a l -in-200 or 0.5 percent probability that sea level rise exceeds th e elevations shown. PA2021-112 INTRODUCTION The subject site is currently separated from the shoreline by an approximately 600 feet wide relatively flat sandy beach, as reflected on the following Photo. The area of the proposed Addition has been mapped by FEMA as Map Zone VE, with a based flood elevation (BFE) of +18.00’ NAVD88. This implies, that from the top of the beach face slope at shoreline at elevation approximately +12’NAVD88, as reflected on the enclosed Topographic Survey, 6’ of water travels across the beach, onto the site, to the landward extent of FIRM Mapped VE Zone. 3 MAP PANELS a saected F1Dod1,tap Bou:ndary Digital DataA\'a.iable fffl~DataA\'aiable unmapped A<eaof , ........ Floodtta,a,d,_< Eff~-elOr.tRs Area of Undetermined F1ood HA?ard zo,w o ~ otherais.e Prot-ected Area 0TH ER AREAS ~ coastal Banie:r Resou:roe system Area. RegulatoryFloodway Z'llneAE.AD,AH, 'E.AR 0.29' Annual Chance Flood Hazard. Areas of 11'annual chance Hood wtth awirage depth less than one foot or with drain.age areas of &e:s.s than one square mlle z-ex Future Condhlons. 1% A.nnuat Chance Flood Haza.rd z-.1 Area with Reduced Flood Risk due to OTHER AREAS OF leY&e. See Notes. Zone x FLOOD HAZARD r' I ,,,1' Area with Flood Risk due to Levee ZGlll!I o E C,os,Sectlon,wlth1,.Annua1Chance --Water Surface E:lev.alion -Coastal Transect ~ Base Flood Elevation line (l3FE.) iiiiiiiiiiiiiii UmttotStudy ---Jurisdiction Boundary -Coastal Transect Ba§efi11e OTHER --Profile Basellne FEATURES ___ Hydrographlc Feature GENERAL 1----Channel, Culvert, or Storm Sewer STRUCTURES t 1 1 1 1 1 I tevtt, Dike, or FloodwaO PA2021-112 The FIRM estimates that the VE Zone is about 250 feet from the seaward property line with a BFE of +18’NAVD88. Site natural grades are at average about +12.3’NAVD88. In reality, the 6’ of water height at approximately +12’NAVD88 berm crest will become 0.0’ of water at the limit of the flood zone, based on the USACOE CEM statement that when a typical wave bore travels across a sandy beach it losses about 1’ of height every 25 feet to at most 50 feet horizontally. FLOODING HAZARD The primary hazard due to flooding from the ocean waters for this site, like majority of the sites located adjacent to Pacific Ocean, would be due to long term Sea-Level Rise. The current water levels in Newport Bay are reflected on the enclosed Datums for Newport Bay Entrance. According to the enclosed Grading Plan C-2, 1st Finished Floor elevation of the proposed development is at +12.70’ NAVD88=+12.90’MLLW. . While Sea-Levels have been Rising for decades, higher rates of raise are forecast for the coming century because of climate change – see enclosed table 28. Increases can be attributed to warmer temperatures, which cause water to expand, as well more liquid mass caused by melting of ice caps. Current estimates of future Sea-Level Rise generally fall in the range of 1-3 ft for the year 2100. Global warming may impact flooding in other ways as well. Warmer water could intensify North Pacific storms, bringing greater wind and wave energy to shoreline in winter and higher intensity precipitation. The Newport Beach Peninsula portion of the Pacific Institute California Flood Risk Map is shown herein as OE S Quadrangle. The dark blue colored areas show the areas where a 100-year Sea- Level Rise of 55 inches is added to the existing FEMA coastal flood elevation shown in light blue. Obviously, the entire Newport Bay area will be affected if sea level rises 55 inches by the year 2100. If the sea level rises in the next several decades as currently estimated, regional measures to mitigate the potential flooding hazard shall be taken. Since 1st Finished Floor elevation of the proposed development is at +12.70’ NAVD88=+12.90’MLLW, it will remain below the High Tide until year of 2074. If deemed necessary, block walls can be built at site property lines to protect the site from flooding between year 2074 and 2096. Thus, the proposed development shall not be a subject to Flooding over the economic life of the structure. WAVE RUNUP Wave runup is the uprush of water from wave action on a shore barrier intercepting Stillwater level. On steeply sloped shorelines, the rush of water up the surface of the natural beach, including dunes and bluffs, or the surface of a manmade structure, such as revetment or vertical wall can result in flood elevations higher than those of the crest of wind-driven waves. See Wave Runup Sketch & Diagram below. 4PA2021-112 During a storm, the sea level rises along the shoreline and allows for waves to break closer to the shoreline and runup on the beach. As acknowledged in Flooding Hazard paragraph above, the historical highest water elevation in Newport Beach is 7.90 feet above MLLW (approximately 7.70 feet above NAVD88). For the highest SLR case, the calculated overtopping rate of the beach, under the eroded beach conditions with 6.0 feet of future SLR is 15.6 ft³/s-ft. For the calculated overtopping rate (Q=q), the height of water and the velocity of this water can be calculated using the empirical formulas provided by the USACOE (Protection Alternatives for Levees and Floodwalls in Southeast Louisiana, May 2006, equations 3.1 and 3.6). For SLR of 6.0 feet with an overtopping rate of 15.6 ft³/s-ft, the water height h = 2.9 feet and the velocity, v = 7.9 ft/sec. The runup water is not a sustained flow, but rather just a pulse of water flowing across the beach. The 2004 USACOE Coastal Engineering Manual (CEM) states as a wave bore travels across a sand beach, the height of the bore is reduced. Based upon observations, this is about 1-foot reduction in bore height every 25 to 50 feet. The site is over 600 feet away, so for the 6.0 feet of SLR case, the wave bore may travel about 130 feet from the shoreline, which is well short of the site. Rather than being inundated by sea level rise, the beach and the nearshore will readjust to the new level over time, such that waves and tides will see the same profile that exists today. Due to this principle of beach equilibrium, we have beaches today, even though sea level has risen over couple of hundred feet for the last ten thousand years. It is unlikely that overtopping waters over the next 75 years will reach the subject site, even under extreme weather conditions. Due to the sand profile in front of the site, even if some waters reach the site, they will not cause erosion and/or damage, because of their relatively low velocity. EROSION HAZARD Erosion refers to the wearing or washing away of coastal lands. Beach erosion is a chronic problem along many open ocean shores of the United States. To meet the needs for comprehensive analysis of shoreline movement, the United States Geological Survey has conducted analysis of historical shoreline changes along open ocean sandy shores of the conterminous United States and has produced an Open-File Report 2006-1219 entitled “National Assessment of Shoreline Change Part 3: Historical Shoreline Change and Associated Coastal land Loss Along Sandy Shorelines of the California Coast”. The report looks at survey data of the following periods: 1800s, 1920s-1930s, and 1950s-1970s, whereas the lidar shoreline is from 1998-2002. The report looks at both long-term and short-term changes. According to the report, the average rate of long-term shoreline changes for the 5 h • d ---·~1. _-- Wave Runup Sketch Wave runup terms from ACES anal,ysis. PA2021-112 State of California was 0.2±0.1 m/yr., and accretional trend. The average rate of short-term shoreline change for the state was erosional; with an average rate of -0.2±0.4 m/yr. The beach footprint of this site is stabilized and not subject to significant long-term erosion. Review and analysis of historical aerial photographs and field measurements for seawall repairs in the area show no change in the position of the shoreline over the last several decades. The future shoreline changes over the next 75 years are assumed to be the same as in the previous several decades. However, there is a rapid rate of Sea-Level Rise predicted in the next 75 years. If that prediction holds true, the rapid Sea- Level Rise may accelerate shoreline erosion, but it shall not impact the structure on the subject lot over its economic life. CONCLUSION In conclusion, flooding, wave runup and erosion will not significantly impact this property over the proposed life of the development. Thus, need for a shoreline protective devise other that the above-mentioned site block walls is not anticipated over the economic life of the proposed structure to protect it from flooding, wave runup or erosion. The above conclusion was prepared based on the existing conditions, proposed drawings, current projection of future Sea-Level Rise, and within the inherent limitations of this study, in accordance with generally acceptable engineering principles and practices. We make no further warranty, either expressed or implied. PMA Consulting, Inc. appreciates the opportunity to be of service to you. Should you have any questions regarding this report, please give us a call. Respectfully submitted, Plamen Petrov, P.E. Principal Enclosures: Location Map Aerial View Topographic Survey Grading Plan C-2 Table 28: Projected Sea-Level Rise (in feet) for Los Angeles 2096 Medium-High Risk Aversion Table 28: Projected Sea-Level Rise (in feet) for Los Angeles 2096 Low Risk Aversion Datums for Newport Bay Entrance Newport Beach OE S Quadrangle 6PA2021-112 7PMA Consulting!) In~. Consulting Structural Engineers 28161 Casitas Ct., Laguna Niguel, CA 92677 Phone: (714) 717-7542 E-Mail: P.Petrov@PMA-BG.com 114 EAST OCEANFRONT NEWPORT BEACH, CA 92663 Balboa Isl nd 114 Oce nfron , PROJECT SITE e port Be ch, Cit .. 8 Ibo R1er · LOCATION MAP JOB. 40121 SHT. DES. PBP DATE 05/03/21 PA2021-112 8PMA Consulting~ In~. Consulting Structural Engineers 28161 Casitas Ct., Laguna Niguel, CA 92677 Phone: (714) 717-7542 E-Mail: P.Petrov@PMA-BG.com 114 EAST OCEANFRONT NEWPORT BEACH, CA 92663 AERIAL VIEW JOB. 40121 SHT. DES. PBP DATE 05/03/21 PA2021-112 9LEGAi DESCRIPTION LOTIOBI.OCKIIMAl'Ofu..5TN~F':JRJ:COFW!:DINBOOK3 f'IIG!'. 37 or ORANGC" COUNTY RCCORDS SURVEYOR'S NOTES I. F'ROJfCT DOICMMA.llfc 0C n.llll.lC \\IOR.G Vl:RTIOJ.. CONUDL DATA5NttT: 11'.-122-14:4'ALUMINUMDl5r.. ElfVA110N-9.179FT(NAVD8ll). ~tJ~~L:/~~G~~~~~~i,~;>N lHISSUIM:Y, ~ :f1~1~ ~ 1////////////I////I////I; ~c,;,'i,iy WATl'.R M~R\ _COMM ~~,:"'" ~LDING ~ r5urr ll.1~"''·3 "'A'LLEY•ii.32 11.27 11.17 .,,_,., r•ll.39 ~"Q,o! •12.;1~;~ ~~~~ j •11.31 ~8 ~-~ 12.011N;~?;~~ ~ j1;,6<; ~ I< ITT•~~.~ ~12.01' 11.!!5• ~~::;~~~•11.95 • uit uit eb if)! i01~ EAST OCEANFRONT GRAPHIC SCALE k.-.~ !~~~)rt. L£GEND: ??&W~ F'ROPERIYU~C wooor~cc: MfTAl/WIRf~NCI'. OVfRHEADWIR5 c=J CONCRrn c~ c---=i n~ c=J c=J Gf/.A55/NATURALGROUND '"'¼, SPOT l'.L!VATION TR,ffTRUNt::.,...,.PIWXIMATI'. ."t-"·--·-DIAMITTF: IN ltlO"I~ '--' ..._TmORJPUNC ABBREVIATIONS "-DJ ADJACENT 8LDG BUILDING CA CfNTl'.RUNI". 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FU THE REST OF'THETRENCH 'MTH CRUSt£D ROCK TO 4"FROM10PCJ"TRENCH. l: I--BUILDING T 1-800-227-2600 AT I.EAST TWO DAYS eErORE YOU DIG UNDERGROUND SERVICE ALERT or SOUTHERN CALlrORNIA k.-.~ OPEN BOTTOM ROCK BASIN DETAIL 2 BOTTOMLESS TRENCH DRAIN DETAIL3 (llfl'lft) llDcb• !. ft. --""---NTS-CONSTRUCTION NOTES: G) PROTECT EXlS1IIG WOOO FENCE ti Pl.ACE. @PROTECTEXISTIIGWAl..l.ltPLJCE. @RO.OCATEEXISJ1NGG,&,SMEIER(8YOTMERS). © MROCAVATE EXISffiG SOILS TO 2.5 FEET DEF'IH Ml RECOMPACT PER satS REPORT RECOMMEtOI.TIONS. @CONSIROCTREINFORCEOCONCR£TEIW!DSCAPEPER-'RCHANDSJRt.lCTUPJJ.. PIN<S @ CONS1RUCT REINFORCEOCONCR£TE SJEF'SAND ENIRT" PER ARCH PUHS. (D CONSiROCT J" PW:. SCHEDUl.E 40, DRMN l..lN[ IJ MINIMUM 1:it SUft 1-S SHOMI PER PIAN Ml ~ ON THIS SHEET. @ INSTALL J"W,,n>, ~N ltt.rr, NOS MODEL 9098 OR EOUAI.ATI..OCATIOHS SHOMI ON Pl.NI. @ CONSTRUCT 12"WllEAND 18"0EEP FRENCH DRMN PER DETM..NO. 1 ON THISStm. @)CONSTRUCT 12°X 12°0PENBOTTOMROCk/GRA\oa.f1UfDGRATEBASINPER OCT~L t«l.2 ON TtlS Stm. Qj) t.ON5TRllCT 6" WllE 8>TTOM TRENCH DRMN PER OCTM. t«l. 3 ON TtlS Stm. .r:"~~~~i~ CCMR J"P.JC -.r:::.·> /.(. [;j:j. N.I SECTION A --NTS--=,jii""'"" . . SECTION B (TYP) N1S PLAN VIEW --NTS--(.) z (/) z ~ f-...J > () & ~If') i~ m s.ng Ase oj Z0 p .. revision dote printing date project SINGLE FAMILY RESIDENCE 114 E. OCEANFRONT NEWPORT BEACH, CA APN: 048-074-26 owner NEWPORT HOMES OEVELOPEMENT, LLC MR. ROBERT J. HALL 755 W. 17TH STREET, UNIT H COSTA MESA,CA 9262 TEL, (714)292-0419 project no. 450-22.4P-4 scale AS NOTED drown NB checked JMA. date D<t./3D/21 sheet title GRADING PLAN sheet no. C-2 2 or 3 PA2021-112 Probabilistic Projections (in feet) (based on Kopp et al. 2014) H++ scenario (Sweet et al. 2017) *Single scenario MEDIAN LIKELY RANGE 1-IN-20 CHANCE 1-IN-200 CHANCE 50% probability sea-level rise meets or exceeds… 66% probability sea-level rise is between… 5% probability sea-level rise meets or exceeds… 0.5% probability sea-level rise meets or exceeds… Low Risk Aversion Medium - High Risk Aversion Extreme Risk Aversion High emissions 2030 0.3 0.2 - 0.5 0.6 0.7 1.0 2040 0.5 0.4 - 0.7 0.9 1.2 1.7 2050 0.7 0.5 - 1.0 1.2 1.8 2.6 Low emissions 2060 0.8 0.5 - 1.1 1.4 2.2 High emissions 2060 1.0 0.7 - 1.3 1.7 2.5 3.7 Low emissions 2070 0.9 0.6 - 1.3 1.8 2.9 High emissions 2070 1.2 0.8 - 1.7 2.2 3.3 5.0 Low emissions 2080 1.0 0.6 - 1.6 2.1 3.6 High emissions 2080 1.5 1.0 - 2.2 2.8 4.3 6.4 Low emissions 2090 1.2 0.7 - 1.8 2.5 4.5 High emissions 2090 1.8 1.2 - 2.7 3.4 5.3 8.0 Low emissions 2100 1.3 0.7 - 2.1 3.0 5.4 High emissions 2100 2.2 1.3 - 3.2 4.1 6.7 9.9 Low emissions 2110* 1.4 0.9 - 2.2 3.1 6.0 High emissions 2110* 2.3 1.6 - 3.3 4.3 7.1 11.5 Low emissions 2120 1.5 0.9 - 2.5 3.6 7.1 High emissions 2120 2.7 1.8 - 3.8 5.0 8.3 13.8 Low emissions 2130 1.7 0.9 - 2.8 4.0 8.1 High emissions 2130 3.0 2.0 - 4.3 5.7 9.7 16.1 Low emissions 2140 1.8 0.9 - 3.0 4.5 9.2 High emissions 2140 3.3 2.2 - 4.9 6.5 11.1 18.7 Low emissions 2150 1.9 0.9 - 3.3 5.1 10.6 High emissions 2150 3.7 2.4 - 5.4 7.3 12.7 21.5 STATE OF CALIFORNIA SEA-LEVEL RISE GUIDANCE APPENDIX 3: SEA-LEVEL RISE PROJECTIONS FOR ALL 12 TIDE GAUGES | 72 TABLE 28: Projected Sea-Level Rise (in feet) for Los Angeles Probabilistic projections for the height of sea-level rise shown below, along with the H++ scenario (depicted in blue in the far right column), as seen in the Rising Seas Report. The H++ projection is a single scenario and does not have an associated likelihood of occurrence as do the probabilistic projections. Probabilistic projections are with respect to a baseline of the year 2000, or more specifically the average relative sea level over 1991 - 2009. High emissions represents RCP 8.5; low emissions represents RCP 2.6. Recommended projections for use in low, medium-high and extreme risk aversion decisions are outlined in blue boxes below. *Most of the available climate model experiments do not extend beyond 2100. The resulting reduction in model availability causes a small dip in projections between 2100 and 2110, as well as a shift in uncertainty estimates (see Kopp et al. 2014). Use of 2110 projections should be done with caution and with acknowledgement of increased uncertainty around these projections. 11PA2021-112 Probabilistic Projections (in feet) (based on Kopp et al. 2014) H++ scenario (Sweet et al. 2017) *Single scenario MEDIAN LIKELY RANGE 1-IN-20 CHANCE 1-IN-200 CHANCE 50% probability sea-level rise meets or exceeds… 66% probability sea-level rise is between… 5% probability sea-level rise meets or exceeds… 0.5% probability sea-level rise meets or exceeds… Low Risk Aversion Medium - High Risk Aversion Extreme Risk Aversion High emissions 2030 0.3 0.2 - 0.5 0.6 0.7 1.0 2040 0.5 0.4 - 0.7 0.9 1.2 1.7 2050 0.7 0.5 - 1.0 1.2 1.8 2.6 Low emissions 2060 0.8 0.5 - 1.1 1.4 2.2 High emissions 2060 1.0 0.7 - 1.3 1.7 2.5 3.7 Low emissions 2070 0.9 0.6 - 1.3 1.8 2.9 High emissions 2070 1.2 0.8 - 1.7 2.2 3.3 5.0 Low emissions 2080 1.0 0.6 - 1.6 2.1 3.6 High emissions 2080 1.5 1.0 - 2.2 2.8 4.3 6.4 Low emissions 2090 1.2 0.7 - 1.8 2.5 4.5 High emissions 2090 1.8 1.2 - 2.7 3.4 5.3 8.0 Low emissions 2100 1.3 0.7 - 2.1 3.0 5.4 High emissions 2100 2.2 1.3 - 3.2 4.1 6.7 9.9 Low emissions 2110* 1.4 0.9 - 2.2 3.1 6.0 High emissions 2110* 2.3 1.6 - 3.3 4.3 7.1 11.5 Low emissions 2120 1.5 0.9 - 2.5 3.6 7.1 High emissions 2120 2.7 1.8 - 3.8 5.0 8.3 13.8 Low emissions 2130 1.7 0.9 - 2.8 4.0 8.1 High emissions 2130 3.0 2.0 - 4.3 5.7 9.7 16.1 Low emissions 2140 1.8 0.9 - 3.0 4.5 9.2 High emissions 2140 3.3 2.2 - 4.9 6.5 11.1 18.7 Low emissions 2150 1.9 0.9 - 3.3 5.1 10.6 High emissions 2150 3.7 2.4 - 5.4 7.3 12.7 21.5 STATE OF CALIFORNIA SEA-LEVEL RISE GUIDANCE APPENDIX 3: SEA-LEVEL RISE PROJECTIONS FOR ALL 12 TIDE GAUGES | 72 TABLE 28: Projected Sea-Level Rise (in feet) for Los Angeles Probabilistic projections for the height of sea-level rise shown below, along with the H++ scenario (depicted in blue in the far right column), as seen in the Rising Seas Report. The H++ projection is a single scenario and does not have an associated likelihood of occurrence as do the probabilistic projections. Probabilistic projections are with respect to a baseline of the year 2000, or more specifically the average relative sea level over 1991 - 2009. High emissions represents RCP 8.5; low emissions represents RCP 2.6. Recommended projections for use in low, medium-high and extreme risk aversion decisions are outlined in blue boxes below. *Most of the available climate model experiments do not extend beyond 2100. The resulting reduction in model availability causes a small dip in projections between 2100 and 2110, as well as a shift in uncertainty estimates (see Kopp et al. 2014). Use of 2110 projections should be done with caution and with acknowledgement of increased uncertainty around these projections. 12PA2021-112 13PA2021-112 14 DHQ: ♦-------+-MHW: 4.68 PA2021-112 Newport BeachNewport Beach Costa MesaCosta MesaCosta MesaCosta MesaHuntington BeachHuntington Beach ¬«1 ¬«55 ¬«1 ¬«55 117°52’30"W 117°52’30"W 117°55’0"W 117°55’0"W 117°57’30"W 117°57’30"W 118°0’0"W 118°0’0"W 33°37’30"N 33°37’30"N 33°35’0"N 33°35’0"N 33°32’30"N 33°32’30"N 33°30’0"N 33°30’0"N 407000mE 407000mE 08 08 09 09 410 410 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 419000mE 419000mE3707000mN37 07000mN08 08 09 09 3710 3710 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 3720 37203721000mN3721000mN This information is being made available for informational purposes only. Users of this informationagree by their use to hold blameless the State of California, and its respective officers, employees, agents, contractors, and subcontractors for any liability associated with its use in any form. This work shall not be used to assess actual coastal hazards, insurance requirements, or property values and specifically shall not be used in lieu of Flood Insurance Studies and Flood Insurance Rate Maps issued by the Federal Emergency Management Agency (FEMA). Data Sources: US Geological Survey, Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Coastal ServicesCenter (CSC), Scripps Institution of Oceanography, Phillip WIlliams and Associates, Inc. (PWA), US Department of Agriculture (USDA), California Coastal Commission, and National Aeronautics and Space Administration (NASA). Imagery from ESRI and i-cubed. Created by the Pacific Institute, Oakland, California, 2009. California Flood Risk: Sea Level Rise 00.511.520.25 Miles 01230.5 Kilometers 1: 2: 3: 4: 5: 6: 7: 8: Seal Beach Newport Beach Tustin not printed Laguna Beach not printed not printed not printed867 1 2 3 54 §¨¦ £¤ ") ¬« Interstate US Highway State Highway County Highway Grid coordinates: UTM Zone 11N meters Adjoining Quadrangles: Map extents match USGS 7.5 minute topographic maps Project funded by the California Energy Commission’s Public Interest Energy Research Program, CalTrans,and the California Ocean Protection Council Newport Beach OE S Quadrangle NAD83 GCS degrees Coastal Zone Boundary Current Coastal Base Flood (approximate 100-year flood extent) Sea Level Rise Scenario Coastal Base Flood + 1.4 meters (55 inches) Landward Limit of Erosion High Hazard Zone in 2100 15 PACIFIC INSTITUTE PA2021-112