Coastal Resource Guide Pleasant Bay and ... - Town to Chatham

Coastal Resource Guide for Pleasant Bay and Chatham HarborLongshore sediment transport: The movement of sedimentroughly parallel to the shoreline due to the action of winds,waves and currents.Marcoalgae: Large aquatic photosynthetic plants that can beseen without the aid of a microscope.MEP (The Massachusetts Estuaries Project): A project toprovide water quality, nutrient loading, hydrodynamic and otherinformation for 89 estuaries in Southeastern Massachusetts.MHW (Mean High Water): A tidal datum. The average of allthe high water heights observed over the National Tidal DatumEpoch.MLW (Mean Low Water): A tidal datum. The average of allthe low water heights observed over the National Tidal DatumEpoch.MORIS (Massachusetts Ocean Resource InformationSystem): an online mapping tool created by CZM and theMassachusetts Office of Geographic and EnvironmentalInformation (MassGIS).National Tidal Datum Epoch: The specific l9-year periodadopted by the National Ocean Service as the official timesegment over which tide observations are taken and reducedto obtain mean values (e.g., mean low water, etc.) for tidaldatums. It is necessary for standardization because of periodicand apparent secular trends in sea level. The present NationalTidal Datum Epoch is 1960 through 1978. It is reviewedannually for possible revision and must be actively consideredfor revision every 25 years.NHESP (The Natural Heritage & Endangered SpeciesProgram): Agency charged with the protection of the state’swide range of native biological diversity. It is part of theMassachusetts Division of Fisheries and Wildlife and is one ofthe programs forming the Natural Heritage network.Nitrogen overloading: The introduction of more nitrogen intoa system than can be naturally assimilated.NOAA (National Oceanic and Atmospheric Administration):A federal agency in the Department of Commercethat attempts to understand and predict changes in Earth’senvironment and conserve and manage coastal and marineresources to meet economic, social, and environmental needs.Outwash: Sediment deposited by streams flowing away from amelting glacier.Overwash: The process of ocean water carrying sedimentover low-lying coastal areas typically during high energy events(storms).Rollover: Barrier beaches and dunes migrate inland as sea levelrises and storms erode the beach and wash the sand over thedune, depositing it on the middle and backside of the beach asoverwash deposits. The wind-blown dunes then rebuild landwardof their former position.Salt Pannes: Shallow depressions in coastal marshes that containvery high concentrations of salt. Pannes retain seawater for veryshort periods of time. When the seawater evaporates, the saltsremain and accumulate over many tidal cycles.Shoal: Typically a long, narrow (linear) bar of sand or gravel, also‘sand bar’, ‘gravel bar’, ‘bedform’.Sub-embayment: A smaller embayment within a larger embayedbody of water.Subtidal: The area of the seafloor below the low tide line that isalways covered by water.Subtidal shoals: A shoal that is always covered by water.Surficial geology: The characteristics of surficial deposits andincluding soils.Tidal amplitude: The difference in elevation between low andhigh tides at a particular point in a body of water.Tidal prism: The total volume of water that flows into anembayment, or inlet and out again with movement of the tide,excluding any fresh water flow.Tide range: The difference in height between consecutive highand low waters. The Mean tidal range is the difference in heightbetween mean high water (MHW) and mean low water (MLW).TMDL: (Total Maximum Daily Load): A calculation of themaximum amount of a pollutant that a water body can receiveand still safely meet water quality standards.USGS (United States Geological Survey http://www.usgs.gov/): A federal agency in the Department of Interior thatprovides impartial information on: the health of ecosystems andenvironments; natural hazards; natural resources; the impacts ofclimate and land-use change; and core science systems in order toprovide timely, relevant, and useable information.Washover fans: A thin, fan-shaped deposit of sedimentemplaced during an overwash event, typically a high-energy eventsuch as a storm.WIS (Wave Information Studies): the U.S. Army Corps ofEngineers produces wave climate information for U.S. coastalwaters. WIS information is generated by numerical simulation ofpast wind and wave conditions, a process called hindcasting.iiiRevetments: A sloped structure consisting of masonry, stone,sandbags, etc. constructed to protect objects or structuresbehind it.Pleasant Bay Alliance 2011