STRATHMERE — “We need another replenishment project,” Committeeman Curtis Corson said Dec. 9, when Township Committee reviewed the latest beach report.
The Stockton University Coastal Research Center surveyed the Strathmere beaches Sept. 27 and 30 and recently delivered its third-quarter report.
“We have lost 25 percent of the sand that was placed on the beach,” engineer Ryan MacNeill said.
The study found that the northern portion of the beaches, concentrated heavily at Tecumseh, Williams and Seaview avenues, benefited greatly from the U.S. Army Corps of Engineers’ nourishment project but by September erosion had begun, mainly concentrated at the recreational beach/nearshore interface.
The project, completed in January 2024, was a joint effort of the Army Corps Philadelphia District, the New Jersey Department of Environmental Protection, Ocean City, Sea Isle City and Upper Township.
The majority (64,656 cubic yards) of the 111,743 overall losses recorded over the summer came from the offshore portions of the surveyed profiles, while 47,088 cubic yards of volume loss took place on the beach.
“The upgraded dune system still provides much-needed storm protection but this feature at the northern profiles (Williams Avenue and Seaview Avenue) remains more vulnerable with the degraded recreational beach and nearshore decreasing the resilience function,” the report states.
According to the study, the summer weather patterns were generally tranquil with gentle to moderate onshore sea breezes resulting in mild conditions. Two minor onshore events occurred Aug. 9-10 and Aug. 16-17, with winds primarily from the south with gusts up to 40 mph and 4- to-6-foot surf along the shoreline.
“The wave climate from these two events caused minor to moderate beach erosion in Strathmere, focused at the northern beach region,” it states.
The study states beaches initially gained sand at all six profile locations, concentrated heavily in the northern region.
Over the summer quarter, the Strathmere beaches lost moderate to significant sand at four of the six locations but substantially in the offshore region concentrated heavily at Williams Avenue.
“Seaview Avenue to the north displayed continued retreat within the recreational beach and nearshore areas during the latest quarterly comparison. The mid-island profiles at Jasper and Tecumseh avenues displayed moderate offshore sand volume losses while the beach and dunes recorded minimal volume losses. The southern two sites at the Sea Isle City boundary remained stable to accretional with gains concentrated below the zero-elevation datum,” according to the study.
The six monitoring sites are First Street at the border with Sea Isle City, 2400 Commonwealth Ave., Jasper Avenue, Tecumseh Avenue, Williams Avenue and Seaview Avenue at Corson’s Inlet.
The study states overall third-quarter loss in sand volume for the Strathmere oceanfront amounted to 111,743 cubic yards, with the loss concentrated at the northern portion of the barrier beach.
By far, the largest recorded loss of sand volume (-66.46 cubic yards) occurred at Williams Avenue close to Corson’s Inlet, which also saw a shoreline retreat of 121 feet.
“The combination of wave approach and refraction around the nearby offshore bathymetry of Corson’s Inlet generates enhanced transport of sand from the oceanfront near the inlet into the main channel,” the study states. “The northernmost developed oceanfront is constantly under erosional stress if large offshore sand supplies are not present as a result of inlet processes,” according to the study.
The southern profiles recorded minor beach volume gains.
The most significant shoreline position retreat was also seen at the Williams Avenue location.
Monitoring locations:
— First Avenue: This site positioned near the boundary between Sea Isle City and Strathmere, has a 38-year survey history. The dune crest height is 15 feet NAVD88, while width at the toe is about 160 feet. The beach width extends another 300 feet seaward to the median high water line with a berm crest height of about 5-6 feet NAVD88.
— 2400 Commonwealth Ave.: The site is located along the southern undeveloped eastern side of Commonwealth Avenue across the road from 2400 Commonwealth Ave. The current dune crest elevation is 15 feet NAVD 88 and 160 feet in width at the crests. The beach extended an additional 320 feet seaward from the dune toe to the median high water line.
— Jasper Avenue: This site is located at Jasper Avenue, where development of property on the eastern side of Commonwealth Avenue is complete. The dune system there is very stable with foredune accretion occurring throughout the summer months. Overall, the Jasper Avenue site lost minimal material on the beach and dune regions over the summer.
— Tecumseh Avenue: This site provides valuable insight on the transition in the beach orientation and taper into a zone of influence of Corson’s Inlet tidal dynamics on the northern beaches. The timber bulkhead jogs landward south of Sherman Avenue one block south of Sumner Avenue, because of a natural setback in the shoreline. Minor losses occurred on the beach over the summer months. Overall, this location has remained stable since the most recent beach replenishment project was completed.
— Williams Avenue: This site is located near the southern limit for direct inlet influences. Historically sand intermittently accumulates on this beach naturally as tidal delta sand bars shed off adjacent ebb shoals and eventually migrate landward under favorable conditions and attach to the shoreline. However, beach widths had been progressively moving landward since February 2022 and reached dire conditions as of December 2023. The beachfill provided much-needed relief to the area, adding 121.17 cubic yards of sand to the profile and extending the shoreline seaward by 236 feet. Since June 2024, erosional processes have acted on the upper recreational beach and nearshore regions, culminating in the largest sand losses of the six surveyed profiles. As of September 2024, the dune system remains intact but is approaching the critical junction where erosional processes have historically begun.
— Seaview Avenue: This site is located adjacent to Corson’s Inlet, making it vulnerable to rapid beach changes from inlet dynamics and northeast storms. To mitigate these losses, the previous federal project created a wide bump-out in the beach width. The nourishment project that took place in December/January completely restored the primary dune and recreational beach elevations. From April 2024 to June 2024, the shoreline position retreated 76 feet as nearshore sands migrated seaward. From June to September, the shoreline retreated 116 feet, no longer supporting heavy recreational beach activities. The dune continues to provide infrastructure protection but is in danger of wave approach as the protective beach is no longer acting as a robust buffer from wave attack.
– By CRAIG D. SCHENCK/Sentinel staff