Abstract:
Benanga Dam is located in North Samarinda District, Samarinda City. Karangmumus sub-basin river area ±317,39 km2 and catchment area Benanga (Lempake) reaches ±191,5 km2. Administratively, the water catchment area is located in Muara Badak Subdistrict and North Samarinda District. Changes in hydrological conditions upstream of Benanga Dam have a major influence on changes in surface runoff in the Karangmumus Sub basin river. Long term consideration of the need for clean water as well as the impact of land clearance on increased sedimentation quantity and flood frequency downstream, especially Samarinda City. The width of the current puddle in Benanga Dam is ± 11Ha, while the remaining ±148Ha is covered with weeds (total area of inundation ±159Ha). Changes in land functions upstream of the Karangmumus Sub-Basin river due to coal mining activities, agricultural cultivation and land clearing for other land uses will open up land cover and increase soil surface erosion that potentially increases sedimentation and dam retreading. This study to analyze (i). Biophysical Conditions of the catchment areas, (ii) Dependable Flow in Karangmumus River basin, (iii) Availability of Water and Water Requirement and (iv) Projection of the Reliability of Benanga Dam to meet Water Requirement up to 2035 in North Samarinda District. The research was conducted in the catchment area of Benanga Dam and Benanga Dam. The research method used digital image analysis and GIS method to answer the first goal, Water balance analysis to answer the second and third objectives, projection analysis to answer the fourth goal. Data collected form of primary data in the form of field survey, interview and secondary data from related institutions that support this research. From the analysis resault, it is known that catchment area of Benanga Dam has a significant change of land on the use of plantation, mining and residential land. The amount of water availability of Benanga Dam is : 0,039-3,553 m3/s (average 1,274 m3/s) for 80% (Q80) and 0,21-2,36 m3/s (average 1,40 m3/s) of 90% mainstay discharge (Q90). The utilization of Benanga Dam in domestic water supply and irrigation water demand in 2010 is 0.914 m3/s and the projection up to year 2035 is 1,1223 m3/s
