HYDROLOGICAL INVESTIGATIONS OF MAHANADI BASIN LYING BETWEEN HIRAKUND DAM AND MANIBHADRA USING REMOTE SENSING DATA

Abstract

Water is one of the vital natural resources to mankind. Owing to the overgrowing population, modern industrialisation, urbanisation and increasing demands for irrigation, hydrop rwer generation and water supply, it becomes necessary for the accurate assessment and efficient scientific management of the Water Resources. Thus, before taking up any water resources development project, the probable quantity of water from a basin needs to be estimated. Conventional methods of investigation through ground based survey are tedious, slow and very expensive. Also it is difficult to get recent information from such surveys. Hence, Remote Sensing Technique which is in an advanced stage of development, is becom-ing vensatile tool for such studies because of the accelerated speed, better accuracy, repeated measurements and synoptic caveracy and finally an -integrated data base. Keeping all the factors in view, a detailed study of the Mahanadi basin lying between Hirakud dam and Manibhadra site has been carried out using satellite imagery to find a suitable metho-dology so that reasonably accurate and dependable forecast of stream flows can be made for water resources planning. In carrying out this study, LANDSAT imageries on 1:250, 000 scale were analysed to identify the landuse and landcaver clasees such as thick forest, thin forest, thin forest, low vegetation, cultivated and barren land as well as the entire hydrological soil group catagory in the entire catchment. The topographic slopes were obtained from Survey of India toposheets at 1:250,000 scale. Using these data, along with available rainfall data, stream flows were estimated by using the following two approaches. (i) Rational fo rmul a method (ii) Soil Conservation Service TR-55 Model. The computed monthly stream flows were compared with the observed streamflows with the help of (i) statistical analysis, (ii) hydrographs and (iii) flow.duration curves. It was found that Rational formula method gave, better results than SCS model. However, the above mentioned two arproaches could be impro-ved if adequate rainfall data and time sequent LANDSAT imagery could be available. The results of these studies were very encouraging and this methodology, with suitable modification could very well be used for prediction of water yield for the entire Mahanadi basin.