Local characteristics of sediment transport and landform development processes along the coast of Lake Tonle Sap

• Project/Area Number: 18K12577
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 04010:Geography-related
• Research Institution: Public Works Research Institute
• Principal Investigator: NAGUMO NAOKO 国立研究開発法人土木研究所, 土木研究所(水災害・リスクマネジメント国際センター), 専門研究員 (00599665)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Project Status: Completed (Fiscal Year 2022)
• Budget Amount: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2020: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2018: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: 土砂輸送 / モンスーン / 河床材料 / 粒度分布 / 季節変化 / 河口水位変動 / 縦断分級 / 川幅 / 地形発達 / 周期変化 / 水位 / 洪水履歴 / 水位変化 / 流量変化 / 季節変動 / セン川 / トンレサップ湖 / カンボジア / スタウン川 / チャネルバー / 微地形

Outline of Final Research Achievements

In this study, the Lake Tonle Sap in Cambodia and the tributaries that flows into the lake were selected as a study area, by focusing on seasonal changes in the lake level and the water level and discharge of the tributaries, and the characteristics of flow, channel and topography as well as the mechanism of seasonal changes in sediment transport were examined .In the the main target area, the lower Stung Sen River, some areas near the river mouth are submerged due to back water effect of the lake. Sediment transport in the lower Stung Sen River is affected by such seasonal changes, which reveal that the channel width becomes narrower toward the mouth and the bed materials are well sorted, changing the particle size longitudinally.

Academic Significance and Societal Importance of the Research Achievements

本研究は、水理・水文環境の季節変動を伴う、モンスーン環境下における河川の土砂輸送特性を整理するとともに、カンボジアの複雑で多様な生態系を支える湖岸の地形特性や形成史の一端を明らかにしようとする点で学術的に有意義であると考える。また、開発や気候変動等によって従来の環境が変化する、あるいは失われつつある中で、湖岸域の生態系の持続可能性や災害脆弱性、受け得るインパクトへの対応を検討する上での基礎資料としても本研究の必要性は高いと考える。

Research Products

• [Journal Article] Multi-decadal Landform Evolution in the Sittaung River Estuary, Myanmar (2022)
  • Author(s): Nagumo, N. and Egashira, S.
  • Journal Title: Journal of Geography (Chigaku Zasshi) Volume: 131 Issue: 4 Pages: 427-445
  • DOI: 10.5026/jgeography.131.427
  • ISSN: 0022-135X, 1884-0884
  • Year and Date: 2022-08-25
  • Peer Reviewed / Open Access
• [Journal Article] カンボジア低地部の水と暮らし (2019)
  • Author(s): 南雲直子
  • Journal Title: 科学 Volume: 印刷中
• [Presentation] Effect of water level variation on the channel width in the river mouth (2022)
  • Author(s): Nagumo, N. and Egashira, S.
  • Organizer: 10th International Conference on Geomorphology
  • Int'l Joint Research
• [Presentation] Effect of water level fluctuation on the sediment transport and landform development in the river mouth (2022)
  • Author(s): Nagumo, N.
  • Organizer: International Symposium on Engineering Geomorphology, Japanese Geomorphological Union Fall Meeting 2022
  • Invited
• [Presentation] Characteristics of river morphology and bed materials in a tributary river influenced by Lake Tonle Sap (2021)
  • Author(s): Nagumo, N., Egashira, S., Kubo, S. and Ben, B.
  • Organizer: 34th International Geographical Congress
  • Int'l Joint Research
• [Presentation] セン川下流域の川幅と河床材料の粒度分布特性について (2021)
  • Author(s): 南雲直子，江頭進治，久保純子
  • Organizer: 日本地球惑星科学連合2021年大会
• [Presentation] Bank erosion owing to tidal currents and its impact on village distribution on the Sittaung River estuary, Myanmar (2020)
  • Author(s): Nagumo, N., Harada, D., Ahmed, T.S., Egashira, S.
  • Organizer: JpGU-AGU Joint Meeting 2020
• [Presentation] 湖水位の影響を受ける河川の地形および材料特性ートンレサップ湖に流入するセン川を対象としてー (2019)
  • Author(s): 南雲直子、江頭進治、久保純子、BEN Bunnarin
  • Organizer: 日本地形学連合2019年秋季大会
• [Presentation] メコンデルタ、オケオ遺跡における古代運河の形成 (2019)
  • Author(s): 船引彩子
  • Organizer: 日本地理学会2019年春季学術大会