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Special Note: This page gives an overview of the results from the sediment analysis conducted in the capstone project. For a full analysis and discussion, please see the Formal Capstone Paper on the Academic Documentation page!
Please use the conceptual model down below as a references for the other sediment components listed in this analysis.
Please use the conceptual model down below as a references for the other sediment components listed in this analysis.
Graphic 1: Displays the conceptual model generated to display the anticipated sediment distribution along Money Island in reference to the implemented NJDEP project in 2022.
Shoreline Change at Money Island
Shoreline Change at Money Island
MI_LULC_2015.pdfGraphic 2: Money Island land use/land cover map (2015). Data provided from New Jersey's Geographic Information Network (Land use/Land cover 2015).
MI_ShorelineChange.pdfGraphic 3: Shoreline Change (2007-2022)
MI_ShorelineChange2017.pdfGraphic 4: Shoreline Change (2017-2022)
Shoreline Change: 2007-2012-2022 (Graphic 3)
Results from the G.I.S analysis from 2007 through 2022 shoreline change model did displayed significant coastline alterations pre and post anthropogenic development removal in 2019. Even between the years 2007 and 2012 (pre development removal), the shoreline was altered slightly (most noticeably along the Southern portion of the beach near Nantuxent Point which saw drastic accretion of sediment). However, the sediment that was deposited near Nantuxent point between 2007 and 2012, was eroded away between the years 2012 and 2022. For the rest of the beachfront, only minor shoreline changes were observed between 2007 and 2012 overall. This is accredited to the development which was located along Money Island until 2019, when NJDEP demolished the properties as part of their Hurricane Sandy Blue Acres project (please see graphic 2). The two major portions of the beach which experienced the largest change in shoreline from 2012-2022, were located landward of the detached breakwaters and just South of the project delineation (littoral cells 3 & 4 in the conceptual model). Coinciding with the installations of five individual detached breakwaters, the NJDEP conducted a beach nourishment (beachfill) along Money Island which aided in the increase sediment and shoreline in littoral cell #4. However, littoral cell #3 was not included in the beach nourishment project, insisting that the beach accumulated sediment during natural littoral drift and tidal patterns. Significant shoreline changes were also seen in littoral cell #5, or North of the stream near the wing wall.
Shoreline Change 2017-2022 (Graphic 4)
A similar results is seen from the shoreline changes from 2017 through 2022 along Money Island. Between the years 2019 (development demolition) and 2022 (NJDEP project completion), significant sediment accumulation was experienced throughout Money Island, especially in the areas noted between littoral cells 3 and 5. Which is exactly what was anticipated by the engineers which designed the habitat enhancement project (Rich Weggel). The differences between the 2019 and 2022 shoreline also match the conceptual model perfectly, as erosion occurred along Nantuxent Point (littoral cells 1 & 2).
Shoreline Change Sept. 2022 - March 2023 (Graphic 5)
Between September 2022 and March 2023, noticeable shoreline changes were observed based on the elevation values collected by the Stockton University Coastal Research Center. Specifically, the shoreline found near Nantuexent point in March 2023 (littoral cell #2) eroded significantly from its positioned in September 2022, while the shoreline located within littoral cell #3 gained significant sediment over the course of the six months. Surprisingly, the shoreline located landward of the breakwaters (littoral cell #4) experienced a period of erosion during the six months, as the shoreline in September 2022 extended further out to sea in comparison to the shoreline in March 2023. As for littoral cell #5, an increased in sediment overall altered the shoreline. Most noticeably within the stream mouth (behind the sheet pile wing-wall) and just adjacent to the stream mouth (to the North).
Shoreline_Change_2022.pdfGraphic 5: Shoreline Change Sept. 2022 - March 2023).
Elevation Change From September 2022 - March 2023
Elevation Change From September 2022 - March 2023
While the shoreline change models display the gradual change of the coastline, or Mean Sea Level "0-ft" elevation lines, the generated Contour Change G.I.S map displayed the sediment distribution change seaward of the beachfront. Based on the Contour Change Map (see below), we can see moderate changes along Money Island from the locations of the "-1 ft" through the "-5 ft" contour lines. As a result of the contour change map it appears that the contours landward of the breakwaters become more uniformed (and aligned) in March 2023 than in September 2022. Noticeable changes in contour elevations can be seen in littoral cell #3 (breakwater #5) and just North of breakwater #1 (littoral cell 5). Although the maps do not overlap each other (separated to prevent confusion), the contours of "-4 ft" through "-5ft" in March 2023 were located closer in proximity to the shoreline, suggesting that an increase in sediment deposition occurred during the six months directly behind the structures. However, some discrepancies in the contour did occur such as directly behind breakwaters #1 & #5 which saw erosion instead of accretion. The contours also displayed significant amount of sediment erosion (especially between the "-1 ft" and "-3 ft" elevations) landward of the detached breakwaters over the course of the six months a those contours in September 2022 extended further out to sea in correlation to the contours in March 2023.
The results from the Shoreline Change and Contour Change maps directly relate to the differences between the Digital Elevation Models generated from both September 2022 and March 2023. When comparing the D.E.M generated in March 2023 to the one created from September 2022, a significant elevation increase overall was displayed around the shoreline at Money Island. Represented by an increase in orange and red coloration (higher NAVD88 elevations), the D.E.Ms alone suggest that the detached breakwaters were successful at increasing landward sediment deposition, even though the project's littoral cell may have seen a net loss of sediment between September 2022 and March 2023 (please see maps below). Although the actual amount of sediment change is not depicted in the D.E.Ms, the sediment volume change and sediment distribution change maps derived from the D.E.Ms did depict specific areas which saw sediment accretion and erosion along Money Island during these six months.
Contours.pdfGraphic 6: Contour Change Map along Money Island from "-1 ft" elevation to "-5 ft" elevation.
MI_DEM_092022.pdfGraphic 7: D.E.M (September 2022)
MI_DEM_032023.pdfGraphic 8: D.E.M (March 2023)
Sediment Volume Change
Sediment Volume Change
Comparable to the results displayed from the contour changes and digital elevation maps, the sediment volume change maps created visual representations of the sediment changes from September 2022 through March 2023 along Money Island. For the sediment distribution map, two classes were created which displayed areas of net gain sediment (accretion) and net loss sediment (erosion). Overall, Most of the coastline along Money Island is depicted as a sediment loss in the sediment change map (red coloration), with significant sediment erosion within littoral cells 1 & 2, as well as in littoral cell 4 (Nantuxent Point and landward of the structures). However, the sediment distribution change map does correlate with the shoreline change and elevation maps with areas of green (accretion) occurring within littoral cells 3 & 5, directly behind the breakwaters 2-4, and in the mouth of the stream adjacent to the sheet piling wing wall.
The sediment volume change map provided specific amounts of volume changes within these designated zones. Specifically, areas within littoral cells 1 & 2 (Nantuxent Point) saw volume changes ranging from -1.5 cubic feet to -5.0+ cubic feet in certain areas. Meanwhile, the areas landward of the detached breakwaters (littoral cell 4) experienced erosion, with a majority of the area experiencing -3.0 to -5.0 cubic feet of change. However, the sediment volume change map resulted in some areas landward of the detached breakwaters experiencing a 0.2 - 1.5 cubic feet of accretion (directly behind breakwaters 2-4). The largest areas of accretion were located South of the structures (littoral cell 3) with an average of 1.5 - 3 cubic feet of accretion, and directly within and adjacent to the stream channel (upwards of 5.0 - 8.5 cubic feet of accretion).
Sediment_Change_Shoreline.pdfGraphic 9: Sediment Volume Change (Net Gain/Loss)
Sediment_Volume_Change_Shoreline.pdfGraphic 10: Sediment Volume Change (Amount in Cubic Feet)
Multibeam & RTK D.E.Ms
Multibeam & RTK D.E.Ms
One of the most significant results of the sediment distribution component of the Money Island detached breakwater analysis, came from the G.I.S digital elevation map generated from a combination of RTK GPS point collection, Total-Station Triangulation, & Mulitbeam Sonar from an R2 Sonic Echosounder. Providing a D.E.M with significant amount of point data allowed for accurate elevations throughout the project delineation, and even included specific elevations in relation to the breakwaters themselves. As a result, clear evidence of sediment deposition became available in September 2022 (see map below), when clear evidence of Tombolo formations (salients) had become apparent (please see map below). Not even one year since NJDEP finished construction activities along Money Island, did salients start to form, which indicated that the structures were indeed successful of increasing sediment deposition landward of the structures by reducing wave energy. Not only did the RTK GPS and Multibeam Sonar provide evidence of Tombolo formations in September 2022, but it also displayed positive results indicating sediment accretion South of the structures (within littoral cell 3), as the elevation was approximately "0-ft" directly behind breakwater #5. Significantly higher in comparison to the other four structures.
March 2023?: TBD
MI_DEM_Breakwater.pdfGraphic 11: D.E.M (September 2022)
Sediment Volume Calculations
Sediment Volume Calculations
As a direct result of the sediment volume calculation model (please see Methodology page for full details of the analysis and equations used), we were able to achieve accurate sediment volumes (in cubic yards) of change for each littoral cell in relation to the conceptual model generated from the Money Island engineering reports. Directly comparable to the G.I.S results presented above (shoreline, D.E.Ms, Contour, Sediment Volume changes, etc.), the sediment volume calculation model provided exact numbers for the amount of sediment gains and losses in each littoral cell. Littoral cells 1, 2, & 4 all experienced sediment loss from September 2022 through March 2023. Littoral cell 1 lost approximately 1,496.26 total cubic yards, while littoral cell 2 lost roughly 2,845.05 cubic yards of sediment. Noticeably, littoral cell #4 (landward of the breakwaters) experienced 1,276.97 cubic yards of sediment lost. Both littoral cells 3 & 5 experienced sediment accumulation with littoral cell 3 seeing an increase of 1,106.83 cubic yards, while littoral cell 5 experienced an increase of 2,258.77 cubic yards of sediment. Therefore, littoral cell #2 saw the largest amount of erosion from natural processes during the six month period, while littoral cell #5 saw the largest accretion in sediment.
Sediment_Volume_Calculations_Shoreline.pdfGraphic 12: Sediment Volume Calculation Model
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