RESEARCH ON RUNOFF CHARACTERISTICS OF SEDIMENT AND WATER QUALITY SUBSTANCES RELATED TO BASIN CONDITIONS

Abstract

The behavior of sediment and other substances in the entire basin is an important factor in maintaining the river channel as well as conserving the aquatic ecosystem at these places. It is especially important to understand transport during flooding, when large amounts of substances are transported. The most recent large-scale flood in Hokkaido, Japan, occurred in August 2003. It struck Hidaka district, causing many injuries and fatalities. The sediment runoff from that flood is still of concern, and examination on its potential effects is awaited. We surveyed dam basins in Hokkaido to study the relationship between the volumes of sediment and water quality components and the geological and vegetation conditions. Sediment transport during flooding is known to have significant impacts on the water environment. To analyze the flood-related runoff characteristics of sediment, the Saru River basin was chosen for its large sediment runoff. This paper summarizes the substance balance of the basin and analyzes the causal relationship between that balance and the conditions of a basin that tends to experience particularly severe damages.