Floodplain Mapping

Authored by: N. N. Ramaprasad , Narayanan Priya

Encyclopedia of Image Processing

Print publication date:  November  2018
Online publication date:  November  2018

Print ISBN: 9781482244908
eBook ISBN: 9781351032742
Adobe ISBN:

10.1201/9781351032742-140000196

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Abstract

Plain areas close to rivers that are vulnerable to frequent floods are floodplains. The floodplains depend on many factors such as catchment area, catchment response, rainfall pattern, evaporation, and recharge and flow rates. Floodplains are formed by continuous deposition of silts brought down from hills. Floodplain contains abundant minerals and fertile soil and easy to evolve. The urban floods are recent phenomenon where the covering of surfaces by impervious materials reduces the infiltration and increases runoff resulting in the flash flood in low-lying areas. Because of the fast catchment response, urban floods are highly unpredictable. The occupation of floodplains in developing countries is of great concern. Floodplain mapping involves careful study of the hydro-geomorphology of the terrain and is essential for planners and developers. Mapping floodplains with accuracy was a gigantic task with the conventional method and challenging until the availability of remotely sensed data. Presently, digital elevation models such as Shuttle Radar Topography Mission (SRTM), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and CartoDEM are widely used in interpreting the surface models. The aerial photographs can cover large areas. Creation of DEM using semiautomatic techniques and manual break lines is economical and accurate. Light detection and ranging uses a laser scanner mounted on an airborne platform and produces an accurate three-dimensional (3D) mapping. Laser pulses measure distances between the emitter and reflected objects. The by-products of the DEM are slope map, aspect, flow direction, and flow accumulation. The low-gradient areas close to rivers determine the floodplains. The logic of obtaining clustered cells of low-gradient areas along the rivers can help us locate floodplains.

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