HYDROLOGICAL INVEESTIGATIONS OF TEL CATCHMENT IN MAHANADI BASIN USING SATELLITE IMAGERIES

Abstract

Water is a highly variable, mobile and vital natural resource of the world. Owing to the overgrowing population, increasing demands for irrigation, hydropower generation and water supply, it become 'very:.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 becoming versatile tool for such studies because of the accelerated speed, better accuracy, repeated measurements and synoptic coverage and finally an integrated data base. Keeping all the factors in view, a detailed study of the Tel catchment at gauge site Kontamala has been carried out using satellite imagery to find a suitable methodology so that teasonabI.y accurate and dependable forecast of stream flows can. be made for water resources planning. In carrying out this study, LASAT imageries no. 141-046 dated 27.4.35 and 29.11.35 (pre—monsoon a post monsoon ) on 1:250,000 scale were analysed to identify the average landuse and land cover classes such thick forest, thin forest, Bushes and Low vegetation, cultivated and barren land and water bodies in the entire catchment. The hydrological soil group and the topographic slope of the catchment were obtained from soil atlas of India and from Survey of India toposheets respectively. Using these data, along with available rainfall data, stream flows were estimated by using the following approaches. (i) Rational Formula Method (ii) Soil Conservation Service 1R-55 model The computed monthly stream flows were compared with the observed stream flows with the help of (i) Statistical Analysis. (ii) Hydrrographs and (iii) Flow duration Curve. It was found that Rational Formula Method gave better results than SCS model. However, the above mentioned two approaches could be improved if adequate rainfall data and time sequent LA^\TDSAT imagery could be available,