Shoreline Monitoring

Beaches in the CNMI are important coastal resources that connect visitors and residents to the ocean. These important ecosystems also have high recreational, aesthetic, economic, subsistence, and cultural value. Their width and shape are naturally ever-changing with the movement of tides and sediment. However, swells and storms drive high energy waves into the shore and exacerbate shoreline movement. For certain beaches, little to no sand volumes replenish the area and may potentially erode until the water threatens nearby infrastructure and endangers users. One actively eroding site is the stretch from Hyatt Regency to Crowne Plaza Resort. Each powerful storm has chipped away the berm. The width has been reduced to the magnitude of endangering a pathway for vehicles to access the beach. The loss of protective sandy beach increases the vulnerability of beach front communities and infrastructure to storm surge and coastal erosion. To understand and document these interactions, DCRM’s Shoreline Monitoring Program studies beach sites to better inform coastal planning and development.

about the program

Since 2016, DCRM’s Shoreline Monitoring program surveys 17 beaches on Saipan, 9 beach transects on Mañagaha, 2 beaches on Tinian, and 4 beaches on Rota. The team uses the Berger surveying method to identify, measure, and track changes within these sites. This data is developed into beach profiles for comparison. Through taking bi-annually beach profiles all of our target sites, we aim to understand our islands’ shoreline dynamics and report our findings yearly for data-driven decision making. Our team comprises of DCRM staff, student interns, and volunteers. We appreciate the notable contribution of NMC and DCRM Summer interns throughout the years to collect field data necessary for beach profiles and analysis.

Resources

To learn about our work on our dynamic shorelines, view our 2022 Shoreline Monitoring Program Story Map.

The following Shoreline Monitoring Data Reports are available to view findings from our program:

Other local studies involving our shorelines are found on the Shoreline Publications page.

Beach Profile Activity is recently developed educational activity that educators can use to teach a simplified and affordable version of our field surveying procedure in their classrooms. Students will gain hands-on experience on the importance of sandy shoreline and conceptualize how climate change impacts erosion. Available for download here.

Below is an interactive map of the Shoreline Monitoring headstakes (where our transects begin) with the accompanying trend, beach profile, and other information:

**Note: ‘Status’ on this map is based on DCRM’s Shoreline Monitoring Program data since 2016. Shoreline morphology trends are time-based and identified by qualitative analysis of each beach profile. Each head stake is the starting point of a transect line and only represents the shoreline at that point to give a general picture of the shoreline contour at that given time. This program is still gaining sufficient data to report long-term trends. Last updated in 2020.

If you are interested in volunteering or learning about shoreline monitoring, please contact the Shoreline Monitoring lead, Mary, at shorelines@dcrm.gov.mp.

Terms on this page:

Accretion – The gradual addition of land by deposition of water-borne sediment

Berm – The nearly horizontal portion of the beach or backshore formed by the deposit of materials by wave action. Some beaches have no berms, while others have several. In the CNMI, the berm is a vertical drop

Beach Profile – The cross-sectional shape of a beach plotted perpendicular to the shoreline

Berger Level – The nearly horizontal portion of the beach or backshore formed by the deposit of materials by wave action. (In the CNMI, the berm is a vertical drop.)

Coastal Hazards – Phenomena that threaten structures, property, and the environment under extreme weather and water conditions

Coastal Planning – Planning process used to create informed management decisions for zoned coastal area. In the CNMI, all of Saipan, Tinian, and Rota are within the coastal zone. 

Erosion – The wearing away of land and the removal of beach (or dune) sediments by wave action, tidal currents, drainage, or high winds

Headstake – The starting point of a transect. Usually marked on a tree or fixed point in paint

Rod Level – Used with a leveling instrument to determine the difference in height between points

Storm Surge – Abnormal rise in seawater level during a storm, measured as the height of the water above the normal predicted astronomical tide

Transect – A straight line or narrow section across the earth’s surface along which observations are made or measurements are taken

Vulnerability – The likelihood of people, property, industry, resources, ecosystems, or historical buildings and artifacts to coastal hazard impacts, such as shoreline erosion