PHOTONIRVACHAK Journal of the Indian Society of Remote Sensing, Vol. 15, No. 1, 1987 AN ASSESSMENT OF THE M ERITS OF REMOTE SENSING TECHNIQUES FOR ENVIRONMENTAL MAPPING : A CASE STUDY FROM KERALA N.D.K. Nair, D.S. Suresh Babu and K. ReghunathenPillai Centre for Earth Science Studies, Trivandrum-695031 ABSTRACT For a proper analysis of any ecosystem and the assessment of environment impact on it, the beating of data on distribution properties and characteristics of land-form, water, vegetalion, soil end rock and even of the typology of cultural pattern are to be evaluated on the basis of the everchanging enthropogenic involvement. The extent to which the techniques of Remote Sensing alone could attain 9is is yet to be ascertained. The direct method for this would be to conduct the resource surveys of specific regions exclusively and separately by remote sensing as well as by field-studies and then compare the results. An extract of a major study pursued in this line in the Coastal Zone of Kerala, India has indicated an authenticity of about seventy percent through remote sensing. Weighing on the comparative time factor involved, the procedure of mapping through remore sensing alone may be advocated. INTRODUCTION The techniques of remote sensing have now made it possible to view any segment of the earth in a variety of spacial, and temporal scales and resolutions. Neverthless to obtain the best results in natural resources, management and evaluation programmes, the application of remote sensing need be complemented with significant field studies very often extending to the microlevel. In the evaluation, geochorial resources such as geomorphological, pedoiogical and other similar aspects may fit in a large time-frame while geotopical elements like agriculture landuse etc. and even the environment shews fluctuating temporal cl~aracteristics. Data on the distribution, properties and characteristics of land form, water, vegetation, soil and rock and even of the topology of cultural pattern can be derived through remote sensing much more faster than through any other known means. But to evaluate the bearing of these data on the basis of everchanging anthropogenic involvement which is obviously necessary for ecosystem analysis and impact assessment of the environment, it is esential to have primary field observations. Recognition and reflection of environmental considerations at every stage of the development process has become the practical essence of long term planning. The development and conservation of natural resources and the preservation and improvement of environment are two complementary aspects that need to be Investigated through a field-oriented and interdisciplinary approach. In order to evaluate the productive territorial opportunities and to determine the demographic capacity of any area, the feasible approach, therefore, is the augmentation of remotely sensed data with sufficient field data. To assess the proportionate requirement of acquisition of data from the field, the direct method would be to conduct the resource surveys of specific regions exclusively and separately by remote sensing as well as by field studies and then compare the results. Such studies need to be oriented to specific aspects for effective comparison. The present paper attempts to elaborate the procedure and achievements of project on the environmental geomorphology of Kerala Coastal Zone, where the data base was consummated in the above lines. The exposition of results is brought out through a case study.