Prismatica Geotech & Engineering Services Private Limited

From the hydrographic point of view a Topographic Survey consists of a series of tasks carried out with the aim of determining the composition of those parts of the earth’s surface which emerge from the water. It includes the coastal relief and the location of permanent natural or artificial objects and features. Such information is partly obtained by determining the position of points on the ground, which allows their shape as well as details of the features to be depicted, enabling their location and description to be charted. Other sources of data include remote sensing processes from aerial photogrammetric information, other airborne sensors or satellite imagery products. In these cases it is necessary to create ground control points in order to adjust the information to the reference frame in use. The term topography often has other applications, for example in oceanography it is used to depict seafloor surfaces or the boundaries of certain water mass characteristics. All these meanings share a common external description of surfaces covering a physical body. This chapter deals with the methods applicable to the description of coastal features as part of hydrographic surveys, particularly with regards to the appearance of the ground and the location of detail. It includes coastlining and location fixes, generally related to the high water line for marine surveys, the information on these areas ranges from this line to the low water line, as well as conspicuous coastal features which allow the mariner to position himself relative to near shore dangers.