At their August 2, 2022 meeting, the City Council adopted the City of Carmel-by-the-Sea’s Climate Adaptation Plan and Climate Action Plan under Resolution 2022-064. Council commented that implementation of these Plans is imperative and requested the Climate Committee to continue to oversee implementation of certain projects, including the Coastal Engineering Study.

At the November 2022 meeting, the City Council adopted Resolution 2022-094 awarding a Professional Services Agreement with EMC Planning Group, for a not-to-exceed fee of $175,000, to conduct the Coastal Engineering Study and Adaptation Planning Project. Key subconsultants for this Study are Integral Corporation and Haro Kasunich & Associates.

To develop the project’s scope of work, the Consultant team reviewed the 2001 Coastal Development Permit for Scenic Road Armoring Repairs, 2003 Shoreline Management Plan (Shonman and D’Ambrosio), 2016 Carmel Shoreline Assessment Update, 2016 Assessments of Shoreline Improvements at Carmel Beach (Easton Geology), and the City’s 2022 Climate Adaptation and Climate Action Plans.

The Coastal Engineering Study will be completed in two phases. Phase 1 consisted of five tasks and was City-funded in the Capital Improvement Plan (CIP), while Phase 2 is funded by a recently-executed California Coastal Commission reimbursement grant of $500,000. Phase 2 will include Hazard Policy review and revisions, public outreach, and adaptation pathway development. The results of Phase 2 will be presented to the City Council and various Commissions and Committees over the next two years.

At today’s City Council Special Meeting, David Revell, PH.D., Principal, and Matt Jamieson, Project Scientist, from Integral Corp will present their key findings of Task 1, Coastal Engineering Condition Evaluation, Task 2, Carmel Climate Change Vulnerability Assessment and the Shoreline and Beach Change Analysis: Seasonal and Long Term, Task 3, Shoreline and Beach Erosion Modeling and Sea Level Rise, and Task 4, Coastal Hazard and Sea Level Rise Vulnerabilities to the City Council and the public. This final presentation to the City Council will complete Phase 1 services.

Below is a brief summary of the findings of Phase 1, Tasks 1- 4:

Phase 1 – Coastal Engineering and Hazard Assessment

Task 1 – Coastal Engineering Condition Evaluation

In December 2022 through February 2023, Haro Kasunich and Associates (HKA) assessed the general condition of the coastal protection structures and stairways that were visible at Carmel Beach. HKA inventoried the length, footprint and other factors of the coastal protection structures. They determined the effectiveness of restacking rip rap revetment structures and lateral/vertical extensions of both revetments and vertical seawalls. HKA estimated the existing life of the structure until it ceases to adequately provide protection for the bluff and roadway. However, this general assessment was not intended to provide detailed engineering evaluations of each structure. These services will be performed over time as part of the separate Shoreline Infrastructure Repair Project under the Capital Improvement Program.

Severe winter storms and ocean wave runup scoured portions of the beach in early 2023, temporarily removing beach sand that covered the lower portions of some coastal protection structures, allowing them to be inspected. These structures consisted of 11 seawalls, 6 revetments, and 11 stairways. It total, HKA inspected 5,537 lineal feet of coastline, which contained 4,119 lineal feet of coastal armoring.

At the March 9, 2023 Forest and Beach Commission meeting, the Consultant team presented their findings of Task 1, Coastal Engineering Condition Evaluation. The Consultant team also presented their key findings of Task 1 to the Climate Committee on November 16, 2023.

The following table summarizes the key issues of the Condition Assessment.

The Task 1, Coastal Engineering Condition Evaluation is located on the City’s website: https://ci.carmel.ca.us/sites/main/files/file-attachments/12176_carmel_beach_adaptation_coastal_protection_assessment_4-27-2023_rev.pdf?1692201318. The associated Task 1 presentation is located on the City’s website: https://ci.carmel.ca.us/sites/main/files/file-attachments/city_council_slideshow_3-9-2023.pdf?1710868888

Task 2 - Shoreline and Beach Change Analysis – Long Term and Seasonal

The Consultant team presented the findings of Task 2 – Shoreline and Beach Change Analysis to the Forest and Beach Commission at their August 10, 2023 meeting. The Consultant team also presented their findings of Task 2 to the Climate Committee on November 16, 2023.

This study determined the seasonal and historical trends of shoreline position and beach sand widths using historic reports and imagery data dating back to the 1940s.

Long Term

The sand affecting Carmel Beach extends beyond the City limits north to include Pebble Beach along the 10^th golf course hole.

Overall, the long-term shoreline position and beach widths have been relatively stable. This indicates a relatively stable amount of sand in the sandy beach compartment.

On average, the beach widths were narrower south of Eighth Avenue, wider at Pebble Beach, and the widest in the dune-backed areas near the Del Mar parking lot.

Seasonal

The beach widths change seasonally, where the narrowest beach widths occur in the spring (after winter storm waves), and the widest beach widths occur in the fall (after small summer waves).

The highest range in beach widths occurs south of Eighth Avenue and near Pescadero Creek (around the offshore rock).

The beach width was most stable in the dune-backed areas near the Del Mar parking lot.

Storm Impacts and Recovery

During strong west swells (often in El Niño years), when beach erosion is highest, most of the sand is moved offshore, exposing bedrock under the sand in some areas.

The highest observed cliff erosion was between 20-40 feet and was observed following the 1982-1983 El Niño.

Recovery after large storm events occur can take a few years, and the area south of Eighth Avenue usually takes the longest.

A link to the Task 2 – Shoreline and Beach Change Analysis is located on the City’s website: https://ci.carmel.ca.us/sites/main/files/file-attachments/carmel_climate_change_va_task2_shoreline_and_beach_change_0.pdf?1699315046. The Task 2 presentation is located on the City’s website: https://ci.carmel.ca.us/sites/main/files/file-attachments/carmel_task_2_presentation_fbcommission_08102023.pdf?1692199802

Task 3 - Shoreline and Beach Erosion Exposure Modeling with Sea Level Rise

At the February 15, 2024 Climate Committee meeting, the consultant team presented their key findings of Task 3, Shoreline and Beach Erosion Modeling with Sea Level Rise and Task 4, Coastal Hazard and Sea Level Rise Vulnerabilities to the Committee and the public. On March 14, 2024, the Consultants presented Tasks 3 and 4 to the Forest and Beach Commission and the public.

The following summarizes the key issues of the Shoreline and Beach Erosion Exposure Modeling with Sea Level Rise. Consultants will present the potential effect of future beach narrowing and cliff and dune erosion hazard extents with sea level rise. The coastal erosion hazard projections include the effect of the existing City’s coastal armoring (such as revetments and sea walls) as well one that considers a future without armoring present. The differences will be useful in Phase 2 of the project when examining the implications of various adaptation strategies.

Summer Beach Width Changes (with Armoring)

It is projected that the width of Carmel Beach will narrow between 50 - 60 feet for each foot of sea level rise. Please note that the sea level rise projection years shown below are approximate estimations. Assuming that the location of the backshore does not change, the following average summer beach conditions are projected:

•  By 2 feet of sea level rise (2060 – 2080), lateral access to areas south of Twelfth Avenue headland may be obstructed.
•  By 3 feet of sea level rise (2070 – 2100), the southern end of Carmel Beach south of Eighth Avenue is projected to be a series of pocket beaches rather than one continuous stretch of dry sand beach. Only during highly recovered conditions will a dry sand beach remain south of Twelfth Avenue.
• By 4 feet of sea level rise (2080 – 2100+), the only continuous dry sand beach remaining will be from the North Dunes sand ramps to Pescadero Canyon. In the south, only two small pockets of dry sand beaches are projected to remain around Eighth Avenue and Eleventh Avenue.
•  By 5 feet of sea level rise (2090 – 2100+), only one pocket of dry sand beach around the North Dunes and the Fourth Avenue stairs are likely to remain.

Coastal Cliff and Dune Erosion

For the armored erosion projection, erosion rates are dampened significantly in the near term. However, with increasing sea level rise, the effectiveness of the armoring is reduced, leading to an acceleration in blufftop erosion above the coastal armoring beyond 1 foot of sea level rise.

In the armored scenario, the following is projected:

•  By 1 foot of sea level rise (2045 – 2060), the areas with the greatest threat of erosion are the private oceanfront properties near Pescadero Canyon, the dune-backed shore between Fourth and Eighth Avenues, the lower cliffs between Eighth Avenue and Eleventh Avenue, and the unarmored cliffs by Twelfth Avenue. 
•  By 2 feet of sea level rise (2060 – 2080), erosion rates accelerate as coastal armoring is more likely to be overtopped by larger waves. Areas behind seawalls have projected erosion hazard distances of 20 to 40 feet.
•  By 4 feet of sea level rise (2080 – 2100+), the highest erosion distance is projected around Twelfth Avenue, where a combination of factors related to local geology, wave heights, and lack of armoring yield projections of retreat up to 150 feet. Areas of the North Dunes around the Del Mar sand ramp also see higher projections of retreat of up to 90 feet, extending to the volleyball courts.

Task 4 – Coastal Hazard and Sea Level Rise Vulnerabilities

The scope for Task 4 was to determine the bluff-top assets and infrastructure potentially exposed to coastal erosion under armored and unarmored conditions. The vulnerability assessment evaluated erosion hazard exposure to land use and structures, roads and parking, and other infrastructure. For succinctness, results of only the coastal armored scenario are presented below. The full suite of results for Tasks 3 and 4 are provided in the technical report provided on the City’s website: https://ci.carmel.ca.us/sites/main/files/file-attachments/carmel_climate_change_va_task3and4_draft_feb_2_2024.pdf?1710870221. The Task 3 and 4 presentation is located on the City’s website: https://ci.carmel.ca.us/sites/main/files/file-attachments/carmel_presentation_climatecommittee_feb2024_0.pptx?1710868563

• Currently, all of the assets and infrastructure along the beach and bluff including 11 coastal access stairways, the Scenic Drive Pathway, and the stormwater drainage network are exposed to erosion. The public restroom adjacent to the Santa Lucia Avenue stairs is exposed to erosion and will face increased threat from coastal wave flooding in the future.

• By 1 foot of sea level rise (2045 – 2060), Scenic Drive is exposed to erosion in 6 locations, largely around Twelfth Avenue and between Tenth and Eighth Avenue. A sewer force main near Martin Way may be exposed, as well as a sewer main between Ninth and Tenth Avenues, and a sewer main under the dunes between Seventh and Eighth Avenues. Waves overtopping the bluff are expected to be more likely along the southern seawall by Santa Lucia Avenue.
• By 2 feet of sea level rise (2060 – 2080), nearly the entire length of Scenic Drive may be exposed to erosion, including most of the underground water and sewer infrastructure. This includes a water main between Eighth and Tenth Avenues. Waves overtopping the bluffs are expected to be more likely between Tenth and Eleventh Avenues.
• Between 2 and 4 feet of sea level rise (2060 – 2100+), 45 homes along Scenic Drive and at Pescadero Canyon are projected to potentially be exposed to erosion. One additional water main under Scenic Drive south of Thirteenth Avenue may be exposed to erosion. One additional sewer force main may be exposed to erosion by Eighth Avenue. The Del Mar parking lot will also be exposed to erosion. Waves overtopping the bluffs are expected to be more likely between Ninth and Tenth Avenues.

Generally, the sea level rise impacts noted in the above report are based on making no further investments in armoring or adaptation to address the anticipated coastal damages. Clearly, inaction or delayed action may result in costly damages and emergency repairs due to the cumulative effect of sea level rise, wave action, flooding, storms, and coastal erosion. Phase 2 of the Coastal Engineering Study will include development of sea level rise adaptation strategies, in collaboration with other City departments, community stakeholders, and the California Coastal Commission, in order to make the City more resilient in the face of rising sea levels. Such efforts may prolong the useful life of Carmel Beach and the shorefront for as long as possible.

Task 5 – Policy Review

Consultants also prepared a memo summarizing Task 5 – Policy Review the City’s existing coastal hazard policies and identifying recommended updates to the Local Coastal Program to be prepared in Phase 2. This memorandum was approved by staff.

At the November 2022 meeting, the City Council adopted Resolution 2022-094 awarding a Professional Services Agreement with EMC Planning Group, for a not-to-exceed fee of $175,000, to conduct the Coastal Engineering Study and Adaptation Planning Project. Key subconsultants for this Study are Integral Corporation and Haro Kasunich & Associates.