Thesis (M. Eng.) - Asian Institute of Technology, 1996

A thesis submitted in the partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development

One of the prime necessity to the human as well as animal society smvival is soil. Only 15 cm of the uppe1most crest of ea1th surface is soil which is fe1tile to produce new wealth. lbis po1tion is constantly getting exposed to the outside agents, those help its weathering. Although new soil fo1mation is there, but ve1y less comparatively much less than the soil erosion, hence the yield decreasing is always there. So conse1ving soil is the prime requirement in todays world. lbis research tries to contribute little to the requirement of the age for planning soil conse1vation measures in the watersheds in a quick, cost effective and precise manner using latest tools available. Soil conse1vation planning in watersheds is still being done by physical smvey method making it sometime infeasible in inaccessiable area. But 'remote sensing technology' can read the land topography (land use/land cover, slope variation and drainage pattern, some times the spectral difference can dete1mine the soil types) ve1y accurately, easily, quickly. It can provide an uptodate inf01mation. USLE is the basic equation get used for this research purpose. The factors are either collected in the field or prepared in the laborato1y with the help of GIS and 'image inte1pretation of remote sensing satellite digital image' technology and different related thematic maps. GIS is a ve1y qualitative tool, that calculate and analyse each of the factors responsible for soil loss in a very efficient manner. This analysis is done for upto the smallest acre ofland with their independent variables. This actualy proves its usefulness. Rainfall erosivity index is calculated by a linear inte1polation of selected values of the prepared iso-erodent map of India, because it is not possible to calculate separately the 'R' factor for the study area as there is no recording type of rain gauge in the study area. No soil map is available for the study area, so soil sample test data and other related info1mation is used to produce one soil map of the study area. It is quite impossible to get first hand infonnation about field slope length, so other approximation method is used. As the area is ve1y much under developped in agriculture and produces only jowar and horsegram, mostly it is considered. Field smvey (ground tmthing) is done to check the land use/land cover types and the supp01ting conse1vation factors in the field. Results of this study represents that the study area is not under so much stress on the soil erosion point of view. The average soil loss rate for the whole watershed is in the pe1missible level, but just on the threshold of eclipsing it. Even some pa1ts of the watershed is subjected to ve1y heavy soil loss. Hence attracts an immediate planning for soil conse1vation program. A tentative soil conse1vation program on plot by plot basis is presented in the text, which can be followed after some varification in the field. A multitemporal analysis of the study area does not present any gloomy character of the study area i.e. the land use/land cover changes in a positive way for sustaination, which is advised to preseve and continue further.