FINAL REPORT FOR 2012 ON THE CONDITION OF THE MUNICIPAL BEACHES IN THE CITY OF BRIGANTINE BEACH, ATLANTIC COUNTY, NEW JERSEY

Transcription

1 FINAL REPORT FOR 2012 ON THE CONDITION OF THE MUNICIPAL BEACHES IN THE CITY OF BRIGANTINE BEACH, ATLANTIC COUNTY, NEW JERSEY Photograph was taken November 3, 2012 from 10 th Street North looking south along the north end promenade towards the end of oceanfront development after Hurricane Sandy. The beach had recently received sand as part of the 2011 ACOE maintenance project that placed sand on the oceanfront beaches from the natural area just north of 14 th Street North to a taper south of 6 th Street North. Sandy caused severe erosion removing most of the sand placed during the 2011 project. At the base of the rock revetment refracted wave energy from the storm scoured away the sand cutting a trough in the beach. By November 3 rd some sand was already starting to move back onshore and partially filled the storm scour trough. PREPARED FOR: THE CITY OF BRIGANTINE BEACH 1417 WEST BRIGANTINE AVENUE BRIGANTINE, NJ PREPARED BY: THE RICHARD STOCKTON COASTAL RESEARCH CENTER 30 WILSON AVENUE PORT REPUBLIC, NEW JERSEY DECEMBER 3, 2012

2 TABLE OF CONTENTS Introduction 1 Municipal Beach Profiles 1 Table 1: Beach Profile Locations 2 Second Half Changes 2 Table 2: Second Half 2012 Beach Volume & Shoreline Changes 3 Changes Since October, Table 3: Annual Beach Volume and Shoreline Changes 4 Post-Hurricane Sandy Changes 5 Table 4: Post Sandy Onshore Beach Volume and Shoreline Changes 5 Individual Profile Site Descriptions Including Figures 1 to 9 (Photographs) 6 Absecon Inlet Jetty Erosion Study 23 Digital Elevation Model 24 Figure 10. Digital Elevation Model of Absecon Inlet Contours 24 Shoreline Migration 25 Figure 11. November 5, 2012 aerial photo of Absecon Inlet area 25 Figure 12. Shoreline Positions 2011 to Figure 13. Digital Elevation Model Annual Elevation Change 27 Inlet Study Summary 28 Report Conclusions 28 Figures 14-22: Municipal Survey Sites Cross-section Plots i

3 Introduction: Annual Report for 2012 to the City of Brigantine Beach on the Condition of Municipal Ocean Beaches Over the course of the last four years there has been five Presidential disaster declarations made for New Jersey s coast in response to three northeast storms and two hurricanes, starting on Presidents Day November 2009 to most recently Hurricane Sandy on October 29, Hurricane Irene passed over the NJ coastline making the first hurricane landfall since The Brigantine City beaches had remained relatively stable and generally accumulated sand across the majority of the southern shoreline prior to Hurricane Sandy. The exception was along the erosional Hotspot from the northend promenade through 6 th Street North. In the early fall of 2011 the US Army Corps of Engineers commenced hauling sand from an Atlantic County quarry on the mainland to augment the erosional section along the northern promenade between 6 th and 14 th Streets North and then tapered into the natural area. The use of trucks to bring quarry sand was the best method to place the relatively small sand quantity funded, well below the volume required to justify the mobilization cost of bringing in a dredge to Brigantine Inlet and placing several thousand feet of pipeline along the natural area beach. This project provided temporary relief from damages suffered during the three northeasters and Hurricane Irene. This past year was dominated by relatively calm weather and seas from December through most of October Conditions deteriorated rapidly with the approach of Hurricane Sandy and its eventual landfall near Atlantic City, New Jersey about 8 p.m. ET on October 29, "Post-Tropical Cyclone Sandy, still packed hurricane-force winds as it moved onshore but had lost the characteristics of a tropical storm about an hour before land fall. Sandy was the second named storm to have struck New Jersey in less than two years following Irene which made landfall in August Sandy's strength, angle of approach and arrival during full moon high tides combined to produce a record storm surge of water into New York City and along the northern New Jersey shoreline. Brigantine located near the eye suffered the full wrath of Sandy s strongest winds that topped 90 mph but avoided the worst of the storm surge, sparing the community from potentially facing similar devastation of property seen in Ocean and Monmouth Counties. Sandy s storm surge and waves still caused significant property and infrastructure damage, erosion along Brigantine s shoreline, lowered beach elevations cut into the dune slope, and removed half a million cubic yards (cy) of sand from the dune and recreational beach. Field surveys were conducted on a semi-annual basis similar to those collected in A post-storm RTK GPS emergency survey of the dune and beach was conducted shortly following Sandy s landfall to document the storm erosion and scope of damage along the shoreline. The Coastal Research Center (CRC) completed the 9 semi-annual beach monitoring profiles on the following dates: October 25, 2011 Survey 75 July 3, 2012 Survey 76 October 26, 2012 Survey 77 November 11, 2012 Survey 78* Note: * Indicates the post Sandy RTK GPS onshore survey The Coastal Research Center (CRC) completed a beach erosion assessment at the Absecon Inlet Jetty under our 2012 contract with the City of Brigantine. On August 2 nd, 2012 the CRC survey crew conducted a complete survey of the Brigantine shoreline adjacent to Absecon Inlet. The survey data were analyzed in ArcGIS software to generate a digital elevation model (DEM) of the area. A shoreline position change analysis was performed to determine shoreline migration rates from 2011 to These results are shown as a separate section at the end of this report. Municipal Beach Profiles: The Richard Stockton College Coastal Research Center established a coastal monitoring program for the City of Brigantine in June 1992, commencing research on the beaches between two major northeast events to 1

4 affect the Jersey shore in October 1991 and December The program collects data from nine shorelineperpendicular beach profile stations, initially monitored on a quarterly basis, to analyze beach changes. Starting in 2008 the program was resumed at a survey frequency of twice annually. Beginning at a fixed reference position, a profile includes the dune system, beach, berm, nearshore and offshore to a water depth of approximately feet (NAVD88). The following table lists the Brigantine sites where cross sections, photographs and field notes are obtained. Table 1: Beach Profile Locations Brig North end Green Acres undeveloped area (NJBPN #134) Brig At the north end of the feeder beach, 1200 feet from road end Brig th Street North Brig 4-4 th Street North (NJBPN #133) Brig 5-5 th Street South Brig th Street South (NJBPN #132) Brig th Street South Brig rd Street South (NJBPN #131) Brig 1 - South Beach 600 feet north of the Absecon Inlet Jetty Second Half 2012 Changes: Relatively mild storm and wave climate conditions persisted along the Jersey shore after Irene and the northeaster of October 2011 that continued through the spring, summer and early fall of Sand from the offshore bar system pushed landward under favorable sea conditions this year filling the nearshore troughs that developed after last year s storms. Gentle summer wave conditions and southeast swells continued to move sand landward eventually added to the onshore beach volume and width by summer season s end. While the beaches and dune gained a modest sand volume onshore longshore currents moved sand offshore in a southerly direction toward Absecon Inlet. The calm seas and mild wind conditions that prevailed through July 2012 to October 2012 were favorable for natural beach building, which added over 119,000 cubic yards (cy) of sand to the system. This pattern abruptly changed with the approach and arrival of Hurricane Sandy on October 29, Sandy followed a rather unusual path for Hurricanes forming in late October. The storm moved around an upper-level low over the eastern United States and also to the southwest of a high pressure ridge over Atlantic Canada, turning it to the northwest. That high pressure system acted like a block, preventing anything from pushing northward, including Sandy, which took a rapid devastating westward turn straight into New Jersey. Sandy passed close enough to a polar trough over the eastern US to become merged into a hybrid cyclone over the Mid-Atlantic and northeast. A dip in the jet stream and the cold front combined to direct and intensify Sandy into Superstorm Sandy at landfall on the Jersey coast. When Sandy made landfall in October the beaches and dunes absorbed the brunt of the storm s energy causing severe erosion. Eliminated were the natural beach and dune gains since Irene plus damage to the dune system not affected by Irene while at the north end the storm surge and waves over washed what remained of the USACE engineered beach. All the beaches were severely eroded and in most locations the dunes cut landward but the overall dune stability was maintained along most of the City of Brigantine Beach, providing ample storm protection for oceanfront properties once again. The USACE engineered beach has now sustained two significant storm events in back to back years but maintained its storm protection in most of the community preventing major flooding from storm wave over wash and dune breaches throughout much of the project area. At the north end chronic erosion along the promenade revetment to 6 th Street North continued to plague this section of engineered beach. Erosion once again exposed the rock revetment and bulkhead removing the USACE maintenance fill volume placed in The beach is narrow with a lower elevation and scour trough along the rock toe. No dune system remains here leaving this region vulnerable to over wash during future moderate storm events. Maintaining a recreational beach and dune feature for storm protection along this erosional hotspot requires regular interval nourishment lacking in the current USACE maintenance cycle. 2

5 Table 2 below shows the summer and fall sand volume changes in cubic yards per foot (yds 3 /ft) of beachfront and shoreline change measured in feet for each of the City's nine profile sites. Also included is a net volume change in cubic yards (cy) for the Brigantine beachfront. The total volume is calculated by averaging the volume change at adjacent profile sites, which is then multiplied by the distance between profile sites. Table 2: Second Half Survey Comparison Brigantine Beachfront Sand Volume and Shoreline Changes July 3, 2012 to October 26, 2012 Profile Shoreline Volume Avg. Volume Distance Net Volume Change Change Change Between Change (feet) (yds 3 /ft) (yds 3 /ft) (feet) (yds 3 ) Brig ,122 1,858 Brig ,860-6,650 Brig ,951 5,151 Brig ,805 9,585 Brig ,729 14,928 Brig ,042 32,975 Brig ,132 60,782 Brig ,855 7,494 Brig ,629 Absecon Jetty Total Volume Change = 119,493 A substantial volume of sand, 119,493 cy was added to the municipal shoreline during the second half of 2012 prior to the arrival of Hurricane Sandy. The net gain is relatively modest if spread across Brigantine s 25,097 feet of shoreline, including the majority of the northern Green Acres tract, amounting to 4.76 yds 3 /ft. of sand. However, the majority of sand accreted from 15 th Street to 43 rd Street adding 93,757 cy of sand or yds 3 /ft. of sand over 7,174 feet of shoreline. This region continues to receive sand transferred south through longshore drift from the project beaches. In response the beach width and elevation have increased annually allowing extensive expansion of the dune system seaward. The long term trend of accretion in this region would allow the city to regularly harvest sand in a sustainable manner to alleviate the chronic erosion at the north end. Changes Since October 25, 2011: Table 3 contains computations on annual shoreline changes and sand volume changes since the end of Beach restoration has had four episodes that started in 1997, followed by restoration in 2001 (funding reimbursed by the Federal Emergency Management Agency (FEMA) following a limited storm 3

6 disaster declaration for a northeast storm February 6, 1998), the initial Federal project in 2006 and finally the recent fall 2011 ACOE maintenance project. All together, a little under 2.5 million cubic yards of sand have been placed on beaches along the northernmost part of the developed portion of Brigantine, with feeder material placed on the undeveloped beach just north of the end of development to provide advance nourishment sand through longshore drift for the area around 12 th Street North. From October 25, 2011 to October 26, 2012 prevailing calm weather and sea conditions allowed natural beach building processes to move sand onshore to the beach and dune system along Brigantine s shoreline. The USACE project was responsible for gains along the promenade while those volume gains in the natural area and south end where derived by longshore and crosshore sand transport. Table 3: Annual Comparison Sand Volume and Shoreline Changes October 25, 2011 to October 26, 2012 Profile Shoreline Volume Avg. Volume Distance Net Volume Change Change Change Between Change (feet) (yds 3 /ft) (yds 3 /ft) (feet) (yds 3 ) Brig Brig Brig Brig Brig Brig Brig Brig Brig Absecon Jetty ,122 43, ,860 29, ,951 18, ,805 6, ,729 3, ,042 28, ,132 42, ,855 5, ,130 Total Volume Change = 176,376 During the past year the City of Brigantine Beach shoreline gained 176,376 cubic yards of sand or 7.03 yds 3 /ft. of sand over Brigantine s 25,097 feet of shoreline, before the arrival of Hurricane Sandy. Nearly half of this 71,583 cy gain of sand accumulated between 15 th Street and 43 rd Street. The north end natural area accumulated another 72,167 cy of sand. The remaining 32,626 cy of sand was spread over the USACE project area and south of 43 rd Street. Only the site immediately adjacent to the Absecon Inlet jetty showed a net sand volume loss for the year which was a very modest loss of 1.88 yds 3 /ft. of sand. The arrival of Hurricane Sandy dramatically reversed the accreational trend for the year making the previous 11 months of gain irrelevant, except to provide an important background trend for sand movement along Brigantine s shoreline under normal weather conditions. 4

7 Post-Hurricane Sandy Changes: Hurricane Sandy made landfall near Atlantic City about 8 p.m. ET on October 29, 2012, as "Post-Tropical Cyclone Sandy. Sandy was the second named storm to have struck New Jersey in less than two years following Irene which made landfall in August The USACE engineered beach provided sufficient storm protection during Sandy s landfall to limit oceanfront property and infrastructure damages along the southern project limits. The beach and dune system suffered significant erosion with losses in width and elevation with up to 10-foot high dune scarps cut into the seaward dune slope, at the northend the dune system was completely removed from 5 th Street North to the natural area. The dune crest remained relatively intact in most of the southern developed locations, which prevented major over wash by storm waves in these locations. Dune breaches and overwash did occur along the developed shoreline in several locations with lower, narrower dunes, breaks or openings in the dune system or where no pre-existing dune existed and resulted in flooding, property and infrastructure damage. Those regions with either large natural dunes or constructed dunes provided an increased level of storm protection to the community. Data collected during the limited emergency survey will provide the City with an initial beach damage assessment and estimates of the dune and beach losses for future restoration efforts. A comparison of the data collected on October 26, 2012 to post-sandy provided shoreline changes and sand volume changes caused by the storm to the recreational beach and dune system. Table 4 below quantify the onshore changes from Sandy, sand volume changes in cubic yards per foot (yds 3 /ft) of beachfront and shoreline change measured in feet for each of the City's nine profile sites. Also included is a net volume change in cubic yards (cy) for the Brigantine beachfront. The total volume is calculated by averaging the volume change at adjacent profile sites, which is then multiplied by the distance between profile sites. Table 4: Post-Sandy Comparison Onshore Sand Volume and Shoreline Changes October 26, 2012 to November 11, 2012 Profile Shoreline Volume Avg. Volume Distance Net Volume Change Change Change Between Change (feet) (yds 3 /ft) (yds 3 /ft) (feet) (yds 3 ) Brig ,122-90,600 Brig ,860-30,541 Brig ,951-31,499 Brig ,805-37,400 Brig ,729-32,912 Brig ,042-21,416 Brig ,132-77,702 Brig , ,740 Brig ,028 Absecon Jetty Total Volume Change = -503,837 5

8 Hurricane Sandy made landfall on October 29th causing significant erosion of the beach and dune system. During the storm the City of Brigantine Beach shoreline lost 503,837 cy of sand or yds 3 /ft. of sand over Brigantine s 25,097 feet of shoreline. Following the storm the beach elevation was on average 2 to 4 feet lower compared to the October 26 th survey and the dunes destroyed at the north end or significantly cut landward with vertical scarps up to 10 feet high. The greatest losses onshore occurred at the northern and southern sites. At the 15 th Street South site the volume loss was minimal 0.40 yds 3 /ft. with sand eroded from the beachface and berm pushed landward essentially burying the bulkhead and spilling over onto the street. This survey was a limited emergency survey and provided coverage only of storm changes onshore, losses and gains offshore related to the storm were not surveyed. As a result it is unknown for certain the quantity of sand eroded from onshore carried to shallow water or deposited further offshore. The extent and rate of natural recovery will be determined by these post-storm offshore conditions and weather patterns this winter. From past trends we can predict much of this eroded sand transferred offshore will be transported south towards Absecon Inlet by the prevailing longshore drift. Individual Profile Descriptions: The beach changes measured between October 25, 2011and October 26, 2012 are displayed below in photographs (Figures 1 through 9). Included along with the annual changes are the post Sandy onshore changes, profile and photographs completed for each site by November 12, Municipal survey site cross-section plots are appended to the end of the report (Figures 14 22). Profile Brig-134: Green Acres - North end (Figures 1a, 1b & 1c) The profile line is located 4,752 feet north of the seawall at the north end of Brigantine Avenue. The dune and vegetation landward of dune toe was all relatively new growth over the last two decades that followed major breeches and over wash during the Dec storm. No new sand was added to the site during any of the nourishment cycles, sand placement started on the feeder beach almost 3,500 feet further south. The development and promenade are barely visible in the right-hand photograph below. Throughout most of the year sand moved landward under favorable weather and sea conditions. Natural beach building added sand from nearshore to the beachface that pushed higher up the beach to the berm raising the recreational beach elevation over a foot. During the year this site gained 7.52 yds 3 /ft. of sand through natural processes. Hurricane Sandy devastated the natural area removing all the gains naturally achieved over the last 20 years since the December 1992 storm last over washed this shoreline. The beach was flattened and lowered up to 5 feet in elevation. Sandy s storm surge and waves over washed the dune system here, completely removing the feature, leaving only old fence post installed after 1992 that mark its previous location. The net onshore volume change from Sandy was a loss of yds 3 /ft. of sand, taken as a wedge extending landward from the shoreline that included the dry recreational beach and dune system. 6

9 Profile Brig-134: Green Acres - North end (Figures 1a, 1b & 1c) Figures 1a, 1b, & 1c. The left photograph taken on October 25, 2011 shows slope modification as wind-blown material accumulated along the dune toe restoring the seaward slope up to the top of the old storm scarp. Photo on the right was taken on October 26, 2012 shows continued sand accumulation across the beach and along the seaward dune slope. Bottom photo taken on November 11, 2012 after Hurricane Sandy shows extensive erosion along the seaward dune slope, only the fence post remain. Hurricane Sandy removed the natural dune and beach recovery gained here since the December 1992 nor easter last over washed this region. 7

10 Profile Brig-220: Feeder Beach - Line (Figures 2a, 2b & 2c) The site is located on the feeder beach portion of Brigantine s engineered beach just north of the promenade on the natural area and provides advance nourishment to the erosional hotspot along the revetment. The goal for this section of the beach was to provide an available sand source to erode and have material move south into the developed portion of the project area to slow erosion in front of the revetment to a more sustainable rate and extend the project benefits for a longer period. This process has been documented to perform better than expected over the past 13 years. The primary dune ridge pre-dates the beach project, but additional sand has accumulated on the seaward crest and slope, blown across the wide berm that remains from the initial and subsequent maintenance beach fill projects. No sand was added directly to this site during the 2011 ACOE maintenance project. The project sand was limited to the promenade region with a small taper into the natural area well to the south of this location. The site has continued to shed sand south and reached a condition were this beach was no longer able to loose sand without losing storm protection for the dune system at the end of In 2012 sand moved landward under favorable weather and sea conditions. Natural beach building added sand from nearshore to the beachface that pushed higher up the beach to form a typical summer berm and raised the recreational beach elevation over 5-feet. During the year this site gained yds 3 /ft. of sand through natural processes from October 25, 2011 to October 26, Hurricane Sandy eliminated all the natural accumulation this year and devastated the dune system constructed during the initial nourishment project, which further developed naturally over the last 15 years. The beach was again flattened and lowered up to 5 feet in elevation. Sandy s storm surge and waves over washed and breached the dune system through sections with lower elevations or eroded away the seaward dune slope back to the crest where the dune elevation was higher. Where the breaches occurred sand was pushed and spread landward filling the back swale. The net onshore volume change from Sandy was a loss of yds 3 /ft. of sand, taken from the upper beach and dune. Along the shoreline a small ridge of sand has begun to move onshore welding to the beach face in less than two weeks post storm. This emergent ridge actually advanced the shoreline position (zero datum) seaward 55 feet post Sandy. Despite this shoreline advance the dry recreational beach berm width retreated nearly 100 feet post Sandy, a better indication of the extent of erosion suffered here. 8

11 Profile Brig-220: Feeder Beach - Line (Figures 2a, 2b & 2c) Figures 2a, 2b, & 2c. Photograph on the left shows the shoreline on October 25, 2011, the expansive width of the feeder beach was depleted allowing higher tides to encroach closer to the dune. In the distance the yellow sand hauled to the beach from inland quarries during the ACOE project can be seen near the end of the promenade slightly tinting the sand from gray to tan in the tidal zone of the feeder beach. Photo on the right taken October 26, 2012 shows the beach accumulated sand onshore raising the beach elevation over the spring, summer and fall of Three days later Hurricane Sandy s storm surge and waves eroded the beach, lowering the elevation and cutting a 4 to 6-foot high scarp along the dune crest while removing the seaward dune slope, as shown in the lower photo taken on November 11,

12 Profile Brig-12: 12th Street North (Figures 3a, 3b & 3c) This monitoring site was established June 1992 along the north side of 12 th Street North. The profile includes the promenade and bulkhead revetment structure that was completely reconstructed prior to the 1997 beach nourishment project. The Federal project placed sand here in February 2006, eventually adding yds 3 /ft. of sand to the beach. This site is within a region of chronic erosion due to the orientation of the beach and revetment that protects the north end of Brigantine Blvd. As the beach retreats to the promenade the rock revetment protection is exposed. The revetment tends to reflect far more wave energy than the beach, so return flow scours the beach elevation downward rapidly. Left unchecked the erosion spreads rapidly south along the revetment towards oceanfront development near 8 th Street North. The feeder beach was designed to alleviate this from occurring by providing advanced sand nourishment to this region in order to maintain a minimal beach seaward of the revetment and prevent exposure of the hard structure. After the series of storm events that started in 2009 and continued through Hurricane Irene in 2011severly eroded this section of shoreline the ACOE conducted a beach maintenance project in fall 2011, to restore a dry beach seaward of the promenade and bury the revetment rocks. The project reestablished a dry beach berm that extended approximately 50 feet seaward of the promenade. The new berm added between 5 and 6 feet of sand vertically to the beach elevation. During most of 2012 the prevailing calm weather and sea conditions allowed this site to remain stable to accretional as sand moved landward to the nearshore and beach. Prior to Sandy the site had gained yds 3 /ft. of sand with a modest shoreline advance of 17 feet. Hurricane Sandy removed all the sand placed in 2011 from onshore. With the rock revetment again exposed the storm waves over washed the promenade caused extensive property damage in the region, deposited large quantities of sand in nearby streets and scoured a deep trough at the base of the revetment. Along the seaward promenade 10 feet of sand was removed vertically by scouring affects as the wave energy reflected off the revetment rocks. Further seaward the beach elevation was lowered 3 to 4 feet with a small ridge of sand located about 40 feet seaward of the revetment appeared to move onshore post Sandy. From onshore this site lost yds 3 /ft. of sand while the shoreline position retreated landward 96 feet. Maintaining a wide feeder beach to the north provides advance nourishment through longshore transport but is dependent on natural processes and conditions. Developing a sand back passing program would allow the City to harvest sand transferred longshore to the southern accreational beaches and mechanically haul the sand back to the erosional zone, effectively recycling and reusing the existing sand within the natural beach system. Conducting such a program on a regular interval is both cost effective vs. hydraulic dredging and would offer the City a means to maintain this chronically eroding shoreline to prevent beach conditions from deteriorating, enhancing storm protection in the future. 10

13 Profile Brig-12: 12th Street North (Figures 3a, 3b & 3c) Figures 3a, 3b, & 3c. The left picture was taken on October 25, 2011 looking south, the 2011 ACOE project had restored a dry berm seaward of the rock revetment covering the previously exposed rocks. The Orange yellow tan tinted sand seen along the revetment is typical of mainland quarry sand in southern NJ. In the photo on the right taken on October 26, 2012 the iron stained sand has been bleached or washed out by the sun and sea, the natural gray color restored over most of the beach. The bottom photo taken on November 3rd shows the severe erosion during Hurricane Sandy removed most of the sand placed during the 2011 project. Within a week some sand was already starting to move back onshore and is positioned here to begin filling the scour trough cut during Sandy. 11

14 Profile Brig-4: 4th Street North (Figures 4a, 4b, 4c & 4d) Brig-4 was established as part of the New Jersey Beach Profile Network in 1986, and included in the City's monitoring project in June The location is at the southern end of the original engineered beach nourishment project area approximately 100 feet south of station No sand was placed in this region during the 2001 maintenance project but sand rapidly moved onto this beach immediately following construction. The initial Federal project extended further south and placed yds 3 /ft. of sand at this site. The fall 2011 ACOE maintenance project ended just north of this location but over the following months and most of 2012 the site received some sand naturally, as sand eroded from the project beaches moved south by littoral currents. Sand accumulated on the upper beach, seaward dune slope and lead to development of a wide recreational berm, adding three feet of elevation to the beachface. From October 2011 to October 2012 the profile accumulated 7.24 yds 3 /ft. of sand with a modest shoreline advance of 10 feet. Hurricane Sandy s waves and storm surge eroded a large wedge of sand from the upper beach and seaward dune leaving a concaved beach slope at this site. The entire fordune feature was over washed and removed leaving a vertical scarp five feet high cut into the primary dune ridge. Sufficient dune width and height remained intact here to prevent a complete over wash at this site. North of this street end the dune rapidly tapers into the now exposed bulkhead near 7 th Street North where over wash was extensive, causing property and infrastructure damage. The depleted nature of this regions shoreline will leave this region vulnerable to future storm damages and requires immediate action to alleviate the post storm conditions. Natural beach building alone will not be sufficient to fully restore this shoreline in its post Sandy condition. Figures 4a & 4b, The left photograph was taken on October 25, 2011 wind-blown sand had accumulated near the dune toe. In the distance the leading edge of the 2011 ACOE project is visible seaward of the red roofed condo; the project is to be tapered into this region upon completion. By October 26, 2012 when the photo on right was taken the 2011 ACOE project was complete and extended the dry beach width seaward. Taken just three days before Hurricane Sandy s arrival storm preparations were under way, note the front end loader tracks in the sand used to push beach sand to the dune toe in an attempt to close the beach access paths in the dune. 12

15 Profile Brig-4: 4th Street North (Figures 4c & 4d) Figures 4c, & 4d. The top photo taken on November 3, 2012 shows the erosion caused by Sandy. The beach width and elevation is reduced, dune slope is cut landward leaving a 5 to 8-foot scarp along the dune crest. The bottom aerial photo taken by Ted Kingston for the CRC on November 5, 2012 shows the extensive loss of shoreline and dune system at the north end of Brigantine. The feeder beach north of the promenade is depleted of excess sand to shed and the beach has been essentially removed seaward of the promenade. South of the promenade the beach is severely eroded the dune system destroyed exposing the old bulkhead, leaving the region vulnerable to future storm damage. 13

16 Profile Brig-5: 5 th Street South (Figures 5a, 5b & 5c) This profile station was selected and established at 5 th Street South in December 1998 because the location was approximately midway between the end of the initial (1997) project beach at 4 th Street North and the established site at 15 th Street South. The Federal project went south beyond this location placing just 8.11 yds 3 /ft. on the beach by March 3, No sand was placed this far south during the recent 2011 ACOE maintenance project. This site has a welldeveloped dune system composed of three significant ridges. The dune system is expansive and continues to grow seaward with sand blown from the wide open beach towards the dune toe adding additional volume and width to the dunes annually. This site over the years has demonstrated a transitional trend between a zone of erosion to the north and accumulation on the southern beaches as sand moves south through this region on littoral currents. During most of 2012 this site was essentially stable with a minor net profile volume gain of 0.48 yds 3 /ft. of sand. The shoreline position advanced seaward 41 feet between October 2011 and October 2012, a result of extensive natural berm development along the beachface slope as sand moved onshore from the bar system offshore. Hurricane Sandy removed much of the sand gained over the past 14 years here. The storm surge and waves flattened and lowered the beach elevation and cut into the seaward dune slope. Erosion resulted in an eight foot vertical scarp at the crest, 75 feet landward of the pre storm dune toe location. Beach elevations were lowered up to three feet while the shoreline position retreated a modest 11 feet. Losses in the dry berm width were more extensive retreating nearly 100 feet, with a loss of yds 3 /ft. of sand from onshore. The remaining dune width and height was sufficient to prevent major over wash in this region, although there was minor over wash through beach access paths, especially prevalent to the north of Roosevelt Blvd. and south between 8 th and 15 th Streets where the dune system was narrower. Redevelopment dune efforts should eliminate these lower beach access paths. Instead crossovers either made of wood or using I-5 gravel to create a hard pack surfaces to walk over dunes should be used to maintain dune height and width integrity. 14

17 Profile Brig-5: 5th Street South (Figures 5a, 5b & 5c) Figures 5a, 5b, & 5c. The photo on the left was taken October 25, 2011, additional sand was blown across the wide beach and accumulated on the seaward slope extending the dune toe seaward. By October 25, 2012 the beach had accumulated sand raising the beach elevation over the summer and fall and pushing the recreational beach berm seaward. The post-sandy photo taken on November 3, 2012 shows significant erosion of the dry recreational beach width and elevation plus a loss of nearly half the primary dune ridge. The crossover in the distance, completely buried by the dune in the October 25 th photo now shows over 20 feet of exposed length, providing a scale for the loss of dune width. Storm waves and surge cut into the dune crest leaving a vertical scarp about 8 feet high. 15

18 Profile Brig-15: 15th Street South (Figures 6a, 6b & 6c) At 15 th Street South, the dune is absent as the near continuous dune system is interrupted by the Ramada Vacation Suites (old Brigantine Hotel, built in 1929) that abuts against the exposed wooden bulkhead between 14 th and 15 th Street South. North of 14 th Street South and south of 15 th Street South the bulkhead is buried below a well-developed dune system. This site is located at a nodule point for the City beaches both from a geographical location and sand deposition and erosion perspective. No sand has been placed here directly during previous beach nourishment efforts as natural sand accumulation has been sufficient to maintain a wide recreational beach. Throughout most of 2012 this site remained relatively stable. Along the upper beach seaward of the hotel the beach elevation was slightly lowered either through wind deflation or excavated to allow for recreational activity and decking. Sand accumulated further seaward forming a wider berm. As sand pushed higher up the beachface from nearshore the berm elevation increased but the shoreline position (zero datum) retreated nearly 43 feet from October 2011 to October Further offshore the seafloor slope was relatively stable with a modest migration of sand landward. The net change for the year was modest with a gain of 1.80 yds 3 /ft. of sand as sand shifted position within the profile. Hurricane Sandy had a major impact on this section of shoreline. North and south of this profile the dune was severely scarped but sufficient width and height remained intact to prevent major over wash and property damage. The absence of a dune between 14 th and 15 th Street allowed the storm surge and waves to over wash the bulkhead pushing a wedge of sand inland. The berm was flattened and sand from the berm pushed landward burying the bulkhead position and street end with up to three feet of sand. Storm over wash carried sand down 14 th and 15 th Streets onto Ocean Avenue. The net onshore loss of 0.40 yds 3 /ft. of sand was minimum since the sand pushed landward to the street end was included in the profile volume. This sand should be pushed back onto the beach to restore the preexisting berm. 16

19 Profile Brig-15: 15th Street South (Figures 6a, 6b & 6c) Figures 6a, 6b, & 6c. The picture from on October 25, 2011 (left) shows the beach elevation is higher and the shoreline advanced seaward burying the rock groin located just north of this site. One year later the recreational beach berm was further developed as sand pushed higher up the beachface, photo from October 25, 2012 on right. The lower photograph taken on November 3, 2012 shows the impact of Hurricane Sandy, the beach is flattened and lower and the dune significantly cut landward leaving a 6 to 8 feet high scarp. 17

20 Profile Brig-27: 27th Street South (Figures 7a, 7b & 7c) This site was established in 1992 for the city s beach monitoring program. The location was selected to fill a void between two preexisting sites, located at 15 th Street South and 43 rd Street south. In contrast to 15 th Street South, Brig-27 has a well-established dune system. The three ridges act as multiple barriers to storm wave damage. Extension of the Absecon Inlet jetty has created a region of backfill that continues to extend north past this site. The jetty will continue to trap sand moving south transported by longshore currents towards the inlet providing a source of sand to feed this dune system and expansion seaward of beach for the foreseeable future. Calm weather and sea conditions during most of 2012 allowed sand to continue to move landward from offshore to the beach. From October 2011 to October 2012 the site gained another yds 3 /ft. of sand adding to the beach width, which pushed the shoreline position seaward another 23 feet. Wind-blown sand was carried from the wide beach to the seaward dune slope adding more sand to the feature. The wide beaches and well developed dune system provided significant protection for ocean front property and infrastructure during Hurricane Sandy, preventing over wash and damage. Storm surge and waves eroded the berm lowering the seaward beach elevation up to 4 feet and pushed sand landward to the dune toe adding more sand to the already wide dune system. The wide beach berm absorbed most of the storm surge and wave energy reducing and flattening the feature but preventing over wash of the dune system. The shoreline retreated 18 feet losing much of the summer expansion along with yds 3 /ft. of sand from the beach and beachface. This site demonstrates the value of a wide, high beach berm and well developed dune system for providing storm protection for oceanfront property and infrastructure. The nature of dominant sand transport along Brigantine s shoreline should allow natural beach recovery to rapidly restore the beach losses when calm weather and sea conditions prevail. 18

21 Profile Brig-27: 27th Street South (Figures 7a, 7b & 7c) Figures 7a, 7b, & 7c. The left-hand photograph was taken on October 25, 2011 and shows the expansive dune development over the last several decades from the 15 th Street South Ramada Suites in the distance and this site. The dune system provides storm protection from typical storm wave damages along the Brigantine City oceanfront from south of the Ramada Vacation Suites building to the Absecon Inlet jetty. The picture to the right taken October 25, 2012 shows the continued natural seaward expansion of the dune system with dune grass and other early colonizing plants spreading out onto the upper beach. Erosional damage caused during Hurricane sandy is evident in the bottom photo taken on November 3, The beach is lower and narrower with loss of the developing berm. Despite the beach erosion ample dune width remained to protect the oceanfront properties during Sandy. 19

22 Profile Brig-43: 43rd Street South (Figures 8a, 8b & 8c) This site was established in 1986 as part of the New Jersey Beach Profile Network and was incorporated in the City's monitoring project in June The profile is located in the area dominated by the sand retention characteristics of the Absecon Inlet jetty. Sand collects all along this beach segment from the Absecon Inlet jetty to about 15 th Street South ever widening the southern section of beach. In 1986 the end of the street was the start of the beach with little dune growth. Today the reference position lies 640 feet landward of a huge dune system that extends to the shoreline position (zero datum) in The present shoreline here is almost a half mile seaward of the shoreline position before the inlet jetty was built in The dune system occupies nearly 800 feet of width between the development and the toe of the big primary dune. Through most of 2012 a smaller foredune developed 20 to 100 feet seaward of the dune toe the beach width continued to expand seaward and the shoreline position was nearly 1,500 feet seaward of the reference position. Sand moved onshore to the beachface welded to the beach and expanded the berm. The shoreline position moved seaward 50 feet in response to the additional sand that moved onshore. Much of this onshore gain was derived from immediately offshore that reduced the net gain to a modest 3.79 yds 3 /ft. of sand across the entire 2000 feet of profile length. In this region Hurricane Sandy s storm surge and wave energy were absorbed over nearly 700 feet of recreational beach that protected the primary dune system from erosion. The small foredune was flattened and swept away but protected the primary dune from direct wave impact. Wave run up on the primary seaward dune slope was marginal and caused little change. A thin veneer of sand was spread across the upper beach. The beach berm absorbed most of the wave impact and suffered the most significant erosion. The berm was cut back landward nearly 200 feet and the elevation of the beach at the pre storm berm crest was 4 feet lower post Sandy. A loss of this nature at many beach locations in New Jersey would have resulted in significant property damage, but here the massive beach and dune system protected the oceanfront property and infrastructure from damage. The net loss in shoreline position (zero datum) was just 10 feet with yds 3 /ft. of sand removed from over 1200 feet seaward of the street end. Prior to Sandy the net gain over just the last several years was nearly 100 yds 3 /ft. of sand with a shoreline advance of over 100 feet. Sustainable growth at this site year after year makes it an ideal location to consider sand harvesting to reuse and redistribute some of this sand back to the northern erosional zone. The process of recycling sand would reduce the cost substantially of repetitive maintenance projects designed to bring new sand to the region from either mainland quarry sites by truck or hydraulically mined and pumped by dredges from the inlet shoals and offshore borrow zones. 20

23 Profile Brig-43: 43rd Street South (Figures 8a, 8b & 8c) Figures 8a, 8b, & 8c. The picture on the left was taken October 25, 2011 the low dune ridge that developed in 2010 was over washed and completely flattened likely the result of storm surge and wave run-up from Hurricane Irene as it made landfall just north of Brigantine. On the right the photo shows the massive width of the dune and beach at 43 rd Street. The seaward dune slope continued to migrate onto the upper beach during most of This beach and dune width was critical during Hurricane Sandy in protecting the oceanfront properties from storm damage. In the bottom picture taken on November 3, 2012 the beach elevation was flattened and lowered by Hurricane Sandy s storm surge and waves. Run up reached the seaward dune slope removing the developing fore dune but most of the energy from those storm waves was absorbed by the more than 600 feet of recreational beach at this site. 21

24 Profile Brig-1: South Beach (Figure 9a, 9b & 9c) Located just 600 feet from the jetty, the site was established to determine if sand simply stopped at the jetty or fluctuated between deposition and erosion as material moved around the end of the rock structure. After several years of observations, the latter response appears to be the way things work. In spring 2009 a cycle of erosion took the berm back to the toe of the dune near the jetty preventing vehicular parking and significant recreational use of the beach at high tide. The pattern reversed with sand moving back to the beach by May In 2011 sand continued to move onshore, establishing a modest dry recreational beach berm that extended about a 100 feet seaward of the dune toe. Landward cross shore sediment transport resulted in sand from the nearshore and offshore seafloor moving to the beach in By July 2012 the recreational beach berm was significantly higher and wider with several feet of elevation added and feet of additional beach width. Over late summer, early fall the acreational trend reversed and sand was lost from the beachface and seafloor. Despite this late season reversal the shoreline advanced seaward 29 feet from October 2011 to October 2012 and onshore the beach gained 6.91 yds 3 /ft. of sand. The onshore gain was offset by losses described above offshore for a modest net volume loss in 2012 of 1.88 yds 3 /ft. of sand, prior to Sandy. Hurricane Sandy caused extensive beach and dune erosion in this location. The narrower beach allowed storm surge and waves to impact the dune directly cutting a vertical scarp nearly 12 feet high at the primary dune crest. Over 40 feet of dune width at the seaward dune toe was lost in this region, removing nearly half the primary dune sand volume. On the beach, storm waves flattened the berm and removed the majority of the dry recreational beach. At the preexisting berm location beach elevations were 5 feet lower after Sandy and the dry beach retreated nearly 100 feet. The net result was a loss of yds 3 /ft. of sand removed from the beach during Sandy. 22

25 Profile Brig-1: South Beach (Figure 9a, 9b & 9c) Figures 9a, 9b, & 9c. The left picture taken on October 25, 2011 right shows an elevated berm and typical vehicle use for this season on a weekday. A Typical summer weekend the number of vehicles using this beach is closer to a hundred making this site an important recreational beach destination. The photo on the right taken from the same location shows the conditions nearly one year later on October 25, Changes to the dune were modest while the recreational beach berm advanced seaward about 40 feet, raising the beach elevation by about one-foot. Post-Sandy bottom photo taken on November 3, 2012 shows the storm eroded caused significant beach erosion and cut back the seaward slope of the dune leaving a steep scarp. However the massive dune system remained largely intact and protected landward property. Absecon Inlet Jetty Erosion Study On August 25 th, 2011 the Coastal Research Center (CRC) completed the initial beach erosion assessment at the Absecon Inlet Jetty. A complete survey of the Brigantine shoreline adjacent to Absecon Inlet was conducted by the CRC field crew to document existing conditions along the inlet shoreline. The survey data 23

26 were analyzed in ArcGIS software to generate a digital elevation model (DEM) of the area. A shoreline position change analysis was performed to determine shoreline migration rates from 1995 to This effort was repeated in A complete survey of the Brigantine shoreline adjacent to Absecon Inlet was conducted by the CRC field crew to document current conditions along the inlet shoreline. ArcGIS software was again used to analyze shoreline position and elevation changes since Digital Elevation Model The survey data were analyzed in ArcGIS software where a continuous, 3-dimensional digital elevation model (DEM) surface was generated by interpolating the RTK GPS (real time kinematic global position system) and total station elevation data between multiple survey lines (Figure 10). The DEM is color coded with the cooler blue colors representing lower elevations and warmer red colors representing higher elevations. Contour lines were created at two foot increments for additional visualization of elevation change throughout the area of study. All elevation units are in US survey feet and are referenced to the North American Vertical Datum 1988 (NAVD88) survey datum. The inlet shoreline has a lobe of sand which extends eastward. Sand by passing the inlet jetty is transferred tidally to the inlet shoreline adding to the lobe of sand. This will eventually migrate eastward and north becoming emergent to form a beach in the inlet at the base of the jetty, barring significant storm events. Much of the inlet beach surveyed was low lying and not much higher than 4ft NAVD88. The ocean facing beach had a fairly wide beach face giving way to a gradual downward slope. Figure 10. Cooler blue colors represent lower elevations, and warmer red colors represent higher elevations. Contour intervals are 2-ft. Elevation units are in the NAVD88 datum. Much of the inlet beach surveyed is low lying and not much higher than 4ft NAVD88. The ocean facing beach has a moderately sized beach face that slopes gradually seaward. 24