吾妻川上流域におけるsuspended sedimentの流出に対する森林率の影響

• 南波 陽平

  砂防学会 東京大学大学院農学生命科学研究科 現:日本工営株式会社

• 堀田 紀文

  砂防学会 東京大学大学院農学生命科学研究科

• 鈴木 雅一

  砂防学会 東京大学大学院農学生命科学研究科

• 執印 康裕

  砂防学会 宇都宮大学農学部

書誌事項

タイトル別名

• The influence of the ratio of forested area on suspended sediment discharge in the upper part of the Agatsuma River basin
• アガツマガワ ジョウリュウイキ ニ オケル suspended sediment ノ リュウシュツ ニ タイスル シンリンリツ ノ エイキョウ

抄録

The relationship between the ratio of forested area (F) and suspended sediment (SS) discharge was examined after eliminating the influence of geography as represented by the average slope gradient in a basin (G). The research area comprised 75 basins nested in the upper part of the Agatsuma River basin (707.9 km²). Using manual sampling, 617 samples were collected between 1994 and 1998, and SS concentrations were determined using the gravimetric method. Water discharge was measured at the time of sampling to estimate SS discharge. After classifying all the data into 3 and 4 groups according to F and G, respectively, sediment rating curves for each group were obtained using the least squares method. By comparing the sediment rating curves, the SS discharge in the basins was found to decrease with higher F, even with scattered data, while no clear relationship was found between SS discharge and G, which means that the forested area had a stronger influence on SS discharge than the geographic characteristics of the research area. Furthermore, we ascertained that the SS concentration converged on a lower value where F was near 1, resulting in especially low SS discharge in wholly forested basins. From these results, we conclude that it is difficult to evaluate SS discharge emphasizing only F, although F is one of the important factors that strongly affects SS discharge. The difficulty, we think, is caused by the existence of fields, which have a strong negative correlation with F in these basins, and which generate SS according to their local geographic characteristics. It is also possible that the relationship between sediment yields and geographic characteristics, which has often been highlighted in previous reports, can be applied only in basins where F is sufficiently high, because most of the research areas in such studies have been limited to upper mountain areas.

収録刊行物

• 砂防学会誌

  砂防学会誌 59 (6), 14-24, 2007

  Japan Society of Erosion Control Engineering

キーワード

• suspended sediment
• the ratio of forested area
• the average slope gradient
• the upper part of the Agatsuma river basin

詳細情報

• CRID: 1390282679043938304
• NII論文ID: 130004296370
• NII論文ID: 10018907974
• NII書誌ID: AN0012035X
• DOI: 10.11475/sabo1973.59.6_14
• NDL書誌ID: 8774720
• ISSN: 02868385
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I8774720
• データソース種別:
  • JaLC
  • NDL
  • CiNii Articles
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