ネパール中央山岳地帯における土砂動態の現状について Sediment dynamics in the mountainous region of the Central Nepal
It could be considered that the sediment dynamics of a basin is characterized by its geomorphometric features, and knowing these features lead to appropriate performances in controlling and mitigating sediment disasters. Almost every year, during the monsoon, due to massive contribution of sediments from the Mahabharat and Siwalik Ranges of the Central Nepal, have been causing countless miserable events to the inhabitants and havoc in the regions. In order to understand the sediment dynamics of the regions, geomorphometric analysis on 16 sub-basins of the regions were conducted. Due to unavailability of sediment discharge and deposition data for the studied areas, floodplain coverage of the studied areas was used to evaluate the sediment dynamics of the regions. All the geomorphometric parameters were determined from 1/25, 000 topographical maps and DEMs. Regarding the floodplain coverage, topographical maps and Landsat-5 TM data acquired in 1988 were used. Apart from the aerial photographs interpretation, field surveys were also carried out to investigate and evaluate the sediment dynamics of the regions. It is suggested from the study that: 1) small basins of the Siwalik Hills have tendency to deposit sediment within the basin; thus, development of floodplains are predominant in the Siwalik Hills ; and 2) Mahabharat basins have capability to flush out most of the sediments yielded in the basins due to their high basin relief and stream drops. The study showed good response to the relationships between morphometric characteristics and sediment dynamics of the studied basins.
- 砂防学会誌 : 新砂防 = Journal of the Japan Society of Erosion Control Engineering
砂防学会誌 : 新砂防 = Journal of the Japan Society of Erosion Control Engineering 60(5), 3-14, 2008-01-15