ABSTRACT
Sediment deposition is the main problem affecting the reservoir. It may have significant impacts and may reduce reservoir life time.
Most of sediment in reservoir originated from watershed erosion. The eroded material transported from the watershed to the land coarse by overland flow.
The amount of sediment inflow to reservoir depends on the amount of sediment yield produced by upstream watershed. Many factors that determined the amount of sediment yield, one of them is ground cover that may change rapidly by human being activities.
This study analyzed the impact of ground cover alteration to the reservoir sedimentation rate in Way Rarem Reservoir for periode of 1992 - 2005. It’s located at Way Rarem river system Kabupaten Lampung Utara.
The result show that, the reduction of forest were 38,98% in 1992-2005. This change has increased erosion rate from 41,79 ton/ha/th in 1992 to 111,43 ton/ha/th in 2005. Consequently reservoir sedimentation rate was also increased from 592,91 m3/km2/th in 1992 to 1.943,37 m3/km2/th in 2005. Because of that, the life time of reservoir was reduced from the proposed 60 years to 31 years.
To extend the life time of reservoir, conservation of the catchments area have to be implemented. The most realistic scenario with deforestation and mechanical conservation concepts as terrace, gulud etc may extend the life time of reservoir to 40 years.
Keyword :Reservoir Sedimentation, Way Rarem
