A reservoir has a capacity of 6.0x106 m3 and a drainage area of 200 km2. The annual stream flow averages 350 mm of runoff and the sediment production is 1100 metric tons per km How long will it take to reduce the reservoir volume to 1.0x10⁶ m³ if the sediment consists of 10% sand, 39% silt and 51% clay.