Studies on Improvement of Water Quality Environment for Using Sabo Dams

• Project/Area Number: 05806022
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: 林学
• Research Institution: Gifu University
• Principal Investigator: KIMURA Masanobu Gifu University, Department of Agriculture, Associate Professor, 農学部, 助教授 (30108063)
• Co-Investigator(Kenkyū-buntansha): TUCHIYA Satoshi Shizuoka University, Department of Agriculture, Associate Professor, 農学部, 助教授 (60197720)
• Project Period (FY): 1993 – 1994
• Project Status: Completed (Fiscal Year 1994)
• Budget Amount: ¥1,800,000 (Direct Cost: ¥1,800,000); Fiscal Year 1994: ¥700,000 (Direct Cost: ¥700,000); Fiscal Year 1993: ¥1,100,000 (Direct Cost: ¥1,100,000)
• Keywords: SS Concentration Ratio / Screen Dam / DO Concentration Ratio / Effect on Reaeration

Research Abstract

1.Effect of Screen Dams on Reducing of Suspended Solids in Flowing Water
The concentration ratio of Suspended Solids (SS) in flowing water was measured periodically in the upper and down site of three screen dams, located in the upper steams of Neo Rivers in the Prefecture Gifu, to clarify the difference of SS concentration ratio owing to the infiltration effect of dams. As a result of measurements, the SS concentration ratio in the down site of dams indicated 7 to 98% less than it in the upper site. The higher the SS concentration ratio showed in the upper site, the more indicated the reducing rate in the down site and took over 80%. For the effect of each dam the measurement results revealed that the reducing rate by it became even stronger with going downstream. The relationships between discharge, velocity of flows and SS concentration were not confirmed.
2.Effect of Falling Works in the Channel Section on lncreasing of Dissolved Oxygen in Running Water
The concentration ratio of Diss olved Oxygen (DO) in running water was measured once in a month in the upper and down site of falling works, located in the channel section of lchinokura River in Tajimi City, to obtain the effects of works on oxygen supply with water falling. According to the measurements, Do concentration ratio in water decreased by slow degrees toward downstream, but increased afresh with falling down the works and showed maximum value in the lowest observation point. The increasing rate took 25% in maximum, but less than 10% in almost cases. The increasing of DO concentration ratio through falling works appeared clearly in the summer, because the photosynthetic activities of water plants is getting livelily with high water temperarure. The increasing rate of DO concentration ratio is closely related with the shape and height of falling works. In the works with water pool apron, the increasing rate indicated 2 to 4% and changed scarcely according to the difference of works height. Compared with this, the increasing rate became more in the proportion to the height in the works with flat concrete apron.