RN-29 : Land use/vegetal cover mapping using satellite data

Abstract

Land use vegetal cover characteristics of a watershed has a significant influence on the quality and quantity of runoff available from it. Various hydrologic processes such as infiltration, evapotranspiration, soil moisture status etc. are influenced by land use/vegetal cover characteristics of a watershed. Thus, it may form an important input to hydrologic models. Hydrologic phenomenon is highly dynamic in nature and as such land use/vegetal cover information may be required of frequent intervals for making hydrologic inferences.

Conventional methods of land use/vegetal cover mapping may not serve the purpose because of limitations of cost, time and the data collection procedure itself. Remote sensing methods especially after the advent of satellites, proved to be advantageous because of the capability to obtain synoptic and repetitive view of the area in the various bands of electro-magnetic spectrum. The efficiency in terms of cost, time and opportunity of integrating existing information into an updated monitoring system is also quite encouraging when remote sensing techniques are resorted to for land use/vegetal cover mapping.

In this report an attempt has been made to review technological advancements in data collection systems and analysis of remotely sensed data for the preparation of land use mapping. Visual interpretation methods of satellite imagery based on tone-texture analysis are time consuming and less accurate. Computer aided analysis of satellite data is faster and more accurate. It is possible to employ various image enhancement techniques and to use various synthetic variables when one uses computer aided analysis.

Since many hydrologic parameters may be expressed in terms of land use and vegetal cover, the need to evolve a hydrologic land use classification scheme on regional basis has also been emphasised. Land use/vegetal cover maps prepared on the basis of such classification scheme could be suitably used for various hydrologic studies like runoff modelling, drought monitoring & estimation of soil erosion.