hydrography

n. mapping of bodies of water (rivers, lakes, etc.)

Hydrography focuses on the measurement of physical characteristics of waters and marginal land. In the generalized usage, "hydrography" pertains to measurement and description of any waters. With that usage oceanography and limnology are subsets of hydrography. In specialized usage the term applies to those measurements and descriptions of navigable waters necessary for safe navigation of vessels.
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Noun
1. the science of the measurement and description and mapping of the surface waters of the earth with special reference to navigation
(hypernym) oceanography

(n.)
The art of measuring and describing the sea, lakes, rivers, and other waters, with their phenomena.
  

(n.)
That branch of surveying which embraces the determination of the contour of the bottom of a harbor or other sheet of water, the depth of soundings, the position of channels and shoals, with the construction of charts exhibiting these particulars.
  

The science which deals with the measurements and description of the physical features of the oceans, seas, lakes, rivers, and their adjoining coastal areas, with particular reference to their use for navigational purposes. 1/3/73

Science qui traite des mesures et descriptions des caractéristiques physiques des océans, mers, lacs, rivières ainsi que des régions côtières voisines, notamment en ce qui concerne leur utilisation pour les besoins de la navigation. 1/3/73