In Japan, many of the recent check dam constructions have been of the open�]type in consideration of the continuity of sediment routing from upstream to downstream reach in a river basin. Over the past 20 to 25 years, much experimental and numerical research has been conducted on sediment control using open�]type check dams. Plans for size and location have been drawn up for grid�]type check dams with heights of around 20 meters in river basins with huge sediment deposition volume in numerous torrents. Hydraulic flume tests are conducted using a straight channel to determine the grid size of grid�]type check dam and to confirm the sediment control function. Subsequently, several runs of flume test are conducted to test three types of debris flow regimes such as rapid flows due to a natural landslide dam break, steady and uniform debris flows, and quasi�]steady debris flows.
In the present study, the sediment control functions of the `grid�]type high dam', which is defined as a grid�]type check dam with a height over 15 m, were examined using several experimental data sets, such as dimensionless sediment runoff volume, temporal changes of mean diameter and sediment concentration and sediment discharge rate passing through the check dam.

Key words�Fgrid�]type check dam, debris flow, hydraulic model test