Suk-Woo Kim

Development of Criteria for Zoning of Debris Flow Hazard Area(II) - The Comparison Between Estimated and Surveyed Values -

This study was to review the previous study, that was zoning the hazard area of debris flow by using the method of setting the reference point based on topography and locational characteristics. The quantity and runout distance of debris flowing were estimated on the subject of Cheonjeon-ri landslided in 2011 and both values were compared with the data of field surveying and aerial photo interpretation. As a results, the effectiveness are on the method of the basic units in each of geology and stream order(b), the empirical method using the Erodible sediment discharge (L 2 ) and the method using the basin area and the spreading angle of debris (L 3 ). In conclusion, these methods were proved in effective because the real debris scale was in the range of the hazard area zoned previously.

Factors controlling sediment production from a yarding road and its temporal pattern in an abandoned clear-cut plantation forest in the Shirasu (pyroclastic flow deposits) area, Kagoshima Prefecture, Japan

To understand the temporal pattern in sediment production from a yarding road, we investigated sediment yield and grain size composition, and examined the relevant physical factors in an abandoned clear-cut plantation forest, based on the 3-year onsite monitoring in Shirasu area, Kagoshima Prefecture, Japan. Under a given amount and intensity of rainfall, although sediment yield and grain size of the sediment increased with increasing rainfall, they remarkably decreased each year; that is, the annual sediment yield from the yarding road in the first, second and third years were 6.1, 2.7, and 1.4 mm, respectively. With the elapsed year, the proportion of gravel and coarse sand gradually decreased, whereas the proportion of fine sand and silt-clay gradually increased. Dry density of surface layers decreased with increasing vegetation coverage at the survey site each year. Additionally, surface grain size at the rill and inter-rill points gradually increased with the elapsed year. The results indicated that the annual decrease in both sediment yield and its grain size are associated with an increase in soil porosity (i.e., increase in infiltration capacity) due to root development and increased intensity of ground resistance to overland flows and sediment transport following both vegetation growth and surface armouring.

Recovery and Disaster Prevention Capability of Coastal Japanese Black Pine (Pinus thunbergii) Forests on the Fukiage Sand Dunes of Southern Kyushu, Japan

In this study, we investigated the Fukiage sand dunes of southern Kyushu, Japan. We surveyed the status of recovery of coastal Japanese black pine forests damaged by pine wilt disease and their disaster prevention capability. We placed two transects: Transect 1, in an area that was severely damaged (80-90% damage rate) by pine wilt disease, and Transect 2, in an area that was mostly undamaged (

A Study on the Safety Inspection of Erosion Control Facilities (I): In Case of Check Dams Located in the Gangwon Region

Recently check dam construction number have been increased by becoming known that effectiveness in the control of the landslide and debris flow. However, check dam management standards are not setting yet. Therefore, this study was carried by provide a basic data for the check dam management and inspection in the Gangwondo. The followings are the results of safety inspection on the 274 check dams, which are located in mountain streams, Gangwondo, Republic of Korea. 1. It was determined that, of 274 check dams inspected, 267 check dams (97.4%) generally had a safe condition but 7 check dams (2.6%) had a bad condition that repair and/or complementary measures are required. 2. The check dams with a bad condition had the ages greater than approximately 20 years. This result should be reflected to future stream management strategy including a timing of the specific inspection for durability of check dams. 3. Our finding suggests that the safety inspection of check dams is able to provide basic information required to maintain their own functions, and thus it should be widely applied to stream management strategy against to sediment-related disasters in the future.