RESEARCH ABOUT DRIFTWOOD EMISSION RATE AND RIVER AND BASIN CHARACTERISTIC OF JAPAN MAIN RIVER

Abstract

This research deals with our investigation regarding the quantity and processing methods of driftwood, collected over a period of 5 years, from 2000 to 2004, by 395 offices of the national Ministry of Land, Infrastructure and Transport (the Cabinet Office for Okinawa Prefecture) and the civil engineering-related section stations at 47 prefectures. Also, the energy abundance of the driftwood based on this driftwood collection quantity was calculated. Next, regarding the 18 river systems of the entire nation, the following three factors were taken as parameters for a factor analysis: the river characteristics, the vegetation areas in the rivers, and the vegetation areas in the basins as calculated from GIS analysis. The results of the factor analysis were used to seek the relationship between the driftwood emission rate and the river characteristics as well as the basin characteristics.
Our results indicate that the driftwood emission rate and the river slope can be considered to be cofactors.