Shoreline Monitoring

The beaches of the CNMI are vital coastal resources for economy, ecology, and recreation. Influenced by currents, wind patterns, and wave energy, shorelines are experiencing erosion (sediment loss) or accretion (sediment gain). Others appear stable. Particular beaches, such as American Memorial Park, are noticeably abraded by strong storm events and subjected to long-term erosion. The loss of shoreline increases the vulnerability of near-shore infrastructure and communities to coastal hazards. DCRM’s Shoreline Monitoring Program studies the state of CNMI shorelines to better inform coastal planning and development.

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. Through taking bi-annually beach profiles all of our target sites, we can gain a better understanding of our changing shorelines and address shoreline erosion.

  • The shoreline characteristics of Micro Beach have changed in response to the storm surge of Super Typhoon Yutu.



To learn about our work on our dynamic shorelines, view our 2020 Shoreline Monitoring Program Story Map. The Shoreline Monitoring Data Report for Saipan and Managaha 2018-2021 is available. Local studies revolving our shorelines are found on the Shoreline Publications page.

Below is an interactive map of the Shoreline Monitoring headstakes (where our transects begin):


**Note: ‘Status’ on this map is based on DCRM’s Shoreline Monitoring Program data since 2016. Trends of shoreline morphology are time-based and are 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. Long-term and short-term statuses are not fully documented and reported as this program is still gaining data and momentum.

If you are interested in volunteering or learning about shoreline monitoring, please contact the Shoreline Monitoring lead, Mary, at


Shoreline 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.)

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

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