lake Topography of basinsphysical feature

Lake basins » Topography of basins

Lakes meet with both the atmosphere and the underlying material of their terrestrial basins and interact with each. The topography and configuration of the lake bottom and the nature of the bottom materials vary considerably. They are of sufficient importance to most lake processes to warrant recognition as basic lake characteristics.

The surface area of a lake can easily be determined by cartographic techniques, but lake-volume determinations require knowledge of lake depths. Throughout the world, lakes important enough to warrant study have been sounded, and many nations have completed comprehensive programs to determine the bathymetry of large numbers of lakes. Lake sounding involves traversing a lake to collect either point or continuous measurements of depth until an accurate survey is made. Modern sounding devices measure the time taken for emitted sound to return after reflection from the bottom, relying on a knowledge of the speed of sound in water. The more sophisticated of these also provide for detection of the depths of stratification in sedimentary materials on the lake bottom. The employment of laser devices from aircraft is a recent development that is based on the transmission of light beams with wavelengths that will penetrate water.

For more practical purposes, lake morphology is a stable characteristic. Shore erosion, sediment deposition and transfer, and other processes, however, including dredging by man, may significantly alter a lake’s bottom topography and thus affect navigation, currents, and ecological factors, such as fish spawning grounds.