BathymetryBathymetry (bə'θɪmətri; ) is the study of underwater depth of ocean floors (seabed topography), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water depth measurements are from Ancient Egypt over 3000 years ago. Bathymetric charts (not to be confused with hydrographic charts), are typically produced to support safety of surface or sub-surface navigation, and usually show seafloor relief or terrain as contour lines (called depth contours or isobaths) and selected depths (soundings), and typically also provide surface navigational information.
Coastal sediment supplyCoastal sediment supply is the transport of sediment to the beach environment by both fluvial and aeolian transport. While aeolian transport plays a role in the overall sedimentary budget for the coastal environment, it is paled in comparison to the fluvial supply which makes up 95% of sediment entering the ocean. When sediment reaches the coast it is then entrained by longshore drift and littoral cells until it is accreted upon the beach or dunes. While it is acknowledged that storm systems are the driver behind coastal erosion.
SubsidenceSubsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope movement. Processes that lead to subsidence include dissolution of underlying carbonate rock by groundwater; gradual compaction of sediments; withdrawal of fluid lava from beneath a solidified crust of rock; mining; pumping of subsurface fluids, such as groundwater or petroleum; or warping of the Earth's crust by tectonic forces.
PeneplainIn geomorphology and geology, a peneplain is a low-relief plain formed by protracted erosion. This is the definition in the broadest of terms, albeit with frequency the usage of peneplain is meant to imply the representation of a near-final (or penultimate) stage of fluvial erosion during times of extended tectonic stability. Peneplains are sometimes associated with the cycle of erosion theory of William Morris Davis, but Davis and other workers have also used the term in a purely descriptive manner without any theory or particular genesis attached.
RidgeA ridge is a long, narrow, elevated geomorphologic landform, structural feature, or combination of both separated from the surrounding terrain by steep sides. The sides of a ridge slope away from a narrow top, the crest or ridgecrest, with the terrain dropping down on either side. The crest, if narrow, is also called a ridgeline. Limitations on the dimensions of a ridge are lacking. Its height above the surrounding terrain can vary from less than a meter to hundreds of meters.
Continental shelfA continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island is known as an insular shelf. The continental margin, between the continental shelf and the abyssal plain, comprises a steep continental slope, surrounded by the flatter continental rise, in which sediment from the continent above cascades down the slope and accumulates as a pile of sediment at the base of the slope.
Integrated coastal zone managementIntegrated coastal zone management (ICZM), integrated coastal management (ICM), or integrated coastal planning is a coastal management process for the management of the coast using an integrated approach, regarding all aspects of the coastal zone, including geographical and political boundaries, in an attempt to achieve sustainability. This concept was born in 1992 during the Earth Summit of Rio de Janeiro. The specifics regarding ICZM is set out in the proceedings of the summit within Agenda 21, Chapter 17.
Multibeam echosounderA multibeam echosounder (MBES) is a type of sonar that is used to map the seabed. It emits acoustic waves in a fan shape beneath its transceiver. The time it takes for the sound waves to reflect off the seabed and return to the receiver is used to calculate the water depth. Unlike other sonars and echo sounders, MBES uses beamforming to extract directional information from the returning soundwaves, producing a swathe of depth soundings from a single ping.
Echo soundingEcho sounding or depth sounding is the use of sonar for ranging, normally to determine the depth of water (bathymetry). It involves transmitting acoustic waves into water and recording the time interval between emission and return of a pulse; the resulting time of flight, along with knowledge of the speed of sound in water, allows determining the distance between sonar and target. This information is then typically used for navigation purposes or in order to obtain depths for charting purposes.
