Sediment production in catchment scale from specific sedimentation of dam reservoirs in Hokkaido, Japan

Abstract

Specific amount of sediment deposition in dam reservoirs is a useful index to appraise the degree of sediment production from the catchments. We examined the relationships between the amount and geomorphic and geological characters of catchments of various sizes in Hokkaido, Japan, by analyzing annual sedimentation records in 105 reservoirs. The 28 of the reservoirs were situated in mountainous areas, and the annual specific sediment yield from the catchments was 178m³/km²/year on average. Sediment yield from the catchments underlain by sedimentary rocks was 8 times larger than those underlain by volcanic rocks, and rainfall pattern was strongly reflected in the sedimentation record. On the other hand, specific sediment yield rates became more dependent on dam utilization by human activities for larger catchments. The data revealed that annual specific sediment yield increased with the size in catchments smaller than 100 km², while the relationship is reversed for those larger than the size.