Studies on Improvement of Water Quality Environment for Using Sabo Dams

1.屏蔽坝对降低流水中悬浮物的影响为了阐明坝体入渗作用对流水中悬浮物浓度比的影响，对岐阜市新河上游的三个屏蔽坝上、下部的流水悬浮物浓度比进行了定期测量。测量结果表明，大坝下部的悬浮物浓度比上部低7%~98%。上部土壤悬浮物浓度比越高，下部土壤悬浮物减少率越大，降幅达80%以上。对于各个大坝的影响，测量结果表明，随着下游的推移，其减少的速度更大。流量、流速与SS浓度之间的关系尚不明确。2.航道段降沙对提高自来水中溶解氧的影响DISS-…浓度比为了解工程落水供氧效果，对位于田上市仁仓河航道段的落水工程上下部进行了每月一次的自来水溶解氧(DO)测定。测量结果表明，水体中的DO浓度比向下游缓慢下降，但随着建筑物的下沉，DO浓度比又重新升高，并在最低观测点出现最大值。上升率最高为25%，但多数病例的上升率在10%以下。随着水温的升高，水生植物的光合作用活跃，DO浓度比的增加在夏季表现得尤为明显。DO浓度比的增加速率与倒塌建筑物的形状和高度密切相关。在有水池围堰的工程中，增长率为2~4%，几乎不随工程高度的不同而变化。与此相比，采用平板混凝土围堰的工程，其增加率与高度成正比。较少

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