Studies on Improvement of Water Quality Environment for Using Sabo Dams

1.筛坝降低流动水中悬浮物的效果在岐阜县新江上游3座筛坝的上、下位置进行了定期的流动水中悬浮物浓度比测定，以澄清由于大坝的入渗作用造成的流动水中悬浮物浓度比的差异。测量结果表明，坝体下部的SS浓度比坝体上部低7 ~ 98%。上部位SS浓度比越高，表明下部位的还原率越高，达到80%以上。对于各坝体的作用，测量结果表明，随着坝体向下游移动，各坝体的降低速率更大。流量、流速与SS浓度之间的关系尚未得到证实。摘要：在田津市赤仓河河段落水工程的上下位置，每月测定一次落水工程对落水供氧的影响，分析了落水工程对水体溶解氧的影响。测量结果表明，水体Do浓度比向下游呈缓慢下降趋势，但随着工程的下降又重新上升，并在最低观测点达到最大值。增幅最大达25%，但多数情况下增幅小于10%。由于夏季水体温度高，水体植物的光合活动变得活跃，因此通过降压工程使DO浓度比增加的现象在夏季表现得较为明显。DO浓度比的增加速率与落物的形状和高度密切相关。在有水池围板的工程中，随着工程高度的不同，其增幅为2 ~ 4%，变化不大。与此相比，平面混凝土围护层的工程中，与高度的比例增加幅度更大。少

1.Effect of Screen Dams on Reducing of Suspended Solids in Flowing WaterThe 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 WaterThe concentration ratio of Diss … More 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. Less