A STUDY ON THE USEFUL LIFE AND CONSERVATION CONCEPT OF TONDANO LAKE IN MINAHASA REGENCY NORTH SULAWESI PROVINCE

• Main Author: MARLINA TEWAL (NIM : 95015308), ANNEKE
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/25650
• Institution: Institut Teknologi Bandung

Lake Tondano is located in Minahasa Regency North Sulawesi Province, and is one of the lakes that has been prioritized handling because of its value as multifunctional lake. However, the function of this lake and its surrounding areas is not properly controlled causing degradation of functions that result in the depreciation of the lake area and the volume of storage. <br /> <br /> Lake Tondano Water Catchment has an area of 18.434,18 Ha with type of land use is dominated by Agriculture (69,62%), Rice Field (14,26%), Shrine (7,22%), Settlement (5,17%), Forest (3.29%) and Open Land (0.45%). Meanwhile, the topography in the Lake Tondano catchment area is dominated by flat slope class which is 60.18% of the area of catchment area, followed by a very steep and steep slope class of 12,72% and 12,71%, then the slope class ramps of 8,65% and last is a steep grade of 5,73%. The soil type in Lake Tondano catchment area is dominated by the Inceptisol land order, parts of Andisol, and Ultisol, and an average rainfall of 2.152,66 mm/year. <br /> <br /> The soil erosion prediction in Lake Tondano catchment area is analyzed based on USLE (Universal Soil Loss Equation) method, and sediment result (Sy) in river is approached by using SDR (Sediment Delivery Ratio) value, while the remaining useful life of Lake Tondano is analyzed by using efficiency trap method and compared with the direct method. <br /> <br /> The result of land erosion analysis based on land cover from BPDAS Tondano at Lake Tondano catchment area is 12,931,929.67 ton/year, equal to 58,460 mm/year and sediment yield from erosion is 1.217.756,71 m3/year or 6,60 mm/year so the the useful life of Lake Tondano is 505 years away. According to the land cover interpretation from Google Earth at Lake Tondano catchment area, the land erosion is 6.450.577,72 tons/year, equivalent to 29,16 mm/year and the sediment yield of erosion result is 607.429,40 m3/year or 3,30 mm/year with the useful life of Lake Tondano is 1.012 years away. The useful life analysis based on bathymetry measurement in 2010, it was predicted that Lake Tondano sedimentation rate is 6.190.118,39 m³/year or 134,1 mm/year, therefore the useful life of Lake Tondano will be 97 years. <br /> <br /> The conservation in Lake Tondano and its water catchment areas, based on the scope of watershed management activities, there are two departments that directly dealing with the management of Lake Tondano and its Water Catchment Areas, they are Ministry of Forestry and Environment (BPDAS Tondano) focusing on agrofoagery conservation methods, while the one that related to the water resources management including the utilization aspect and the control of water damage is physically carried out by the Ministry of Public Works and People's Housing (BWS Sulawesi I) with the activities of Lake Tondano Revitalization. <br /> <br /> The conservation by using agrofoagery method is very effective in reducing the erosion rate in Tondano Lake catchment area, by returning the forest area from 3.29% to 30% of the watershed area, resulted in decreasing 91,4% erosion rate from 58,46 mm/year to 9,57 mm/year. On the other hand, the revitalization of Lake Tondano can reduce the sedimentation rate of Lake Tondano up to 80% so that the rate of Lake Tondano from 134,1 cm/year to 26,8 cm/year. <br /> <br /> In a sustainable management effort, the social and public conservation should be applied where the Government of North Sulawesi Province with the relevant departments/agencies coordinates with the government and departments/agencies in Minahasa District and all community groups to jointly formulate effective activities in accordance with the social value, cultural and economic in Tondano Lake Water Catchment Area.