Mapping land degradation and desertification using remote sensing data

Abstract

Land degradation is the result of both natural and biotic forces operating on the earth. Natural calamities, over exploitation of land resources, unwise land use and the consequences of high inputs agriculture on soil and water resource are of great concern both at national and international level. It aggravated food insecurity in the world especially in the developing countries that calls for combating land degradation and desertification with scientific means. Development of degraded lands in India is one of the options to enhance food production and to restore the fragile ecosystem. The scientific information and spatial distribution of various kinds of degraded lands is thus essential for formulation of strategic plan to arrest the menace of land degradation. Remote sensing provides an opportunity for rapid inventorying of degraded lands to generate realistic database by virtue of multi-spectral and multi-temporal capabilities in the country. The satellite data provides subtle manifestations of degradation of land due to water and wind erosion, water-logging, salinity and alkalinity, shifting cultivation, etc., that facilitate mapping. All India Soil and Land Use Survey (AISLUS) has undertaken the task of land degradation mapping using remotely sensed data and developed a methodology accordingly. The mapping has been conceptualized as a four-tier approach comprising kind of degradation, severity of degradation, degradation under major landform and major land use. Visual mode of interpretation technique based on image characteristics followed by ground verification has been employed for mapping of degraded lands. Image interpretation key has been formulated based on the spectral signatures of various causative factors of different kinds of degraded lands. The mapping legend has been made systematic and connotative. The extent and spatial distribution of different kinds of degraded lands with degree of severity under major landform and major land use in a district could be derived easily from the report published by the organization. Generation of realistic information on degraded lands of the country is utmost necessary. It should be given due importance and taken up on mission mode in order to check further degradation of the environment and loss of top fertile soils. The data base would enable to develop District Information System using advanced technology for periodic monitoring and development of degraded lands.