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DEM Hydro Processing, Catchment Extraction, Water Recourse Management
S., Matharaarachchi D.; de S, Nandaseela S. M. A. T.
Water is one of the resources which have more scarcity in some regions as well as excess in some parts of the world due to over consumption. Therefore proper utilization of water resources and preservation is highly essential when it comes to water resource management. In water resource management identification and protection of river basins and catchment areas is one of the main focused fields. Normally the focus is given to river basins but this study is focused on identification of sub catchment areas within the main catchment. The impacts or any changes occur in sub catchments likely to affect the functionality and the wellbeing of the main catchment. Therefore it is essential to focus on protecting and preservation of sub catchments in water resource management. The study is focused on Pathahewaheta Divisional Secretariat Division; Sri Lanka belongs to the upper catchment of Mahaweli River. Methodology of the study is based on DEM hydro processing using ARC GIS. Both secondary and primary data and observation of elevation were used to create the Digital Elevation Model (DEM) and steps of the process can be state as sink and fill, calculating flow accumulation, calculating drainage network, ordering the drainage network and calculating the catchment areas. After extracting the catchments, it is used to calculate the overland flow length and flow length to outlet. The sub catchment areas were then overlay with land use and land cove of the study area to identify the concentrated areas of human activities. Changes of the land use will also indicate the changes which can be identified in sub catchment area. Increasing population has created many land use and land cover changes during past years. Agricultural activities are also contributing towards the natural overland flow of the catchment areas. Sometimes it contribute towards the increase of infiltration which some time leads to landslides as well. Secondary data as well as primary data on land use and land cover were used to identify the land use changes in the area. Mainly due to human activities this sub catchment properties are changing rapidly. Therefore in this study, a case study has also conducted based on Haragama Grama Niladhari Division (GND) which has severe issues regarding water scarcity. Results indicate that bed rock of Harahama area has some concentration of lime stones and due to the construction of new road the ground water levels has declined rapidly. Main reason is villages are pointing out is the construction of road. They believe that the blasting of bed rock may be the reason. Therefore it clearly indicates that the changes in sub catchments can have direct impact on natural flow of water and it is important to study them for local government planning schemes, regional plans and other authorities to making decision
Full text: Ab 0486.pdf [Bibtex]
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