River bed erosion prevention for water level preservation - involves depositing layers of sand and gravel mixture and periodic topping up

摘要

For combating unevenness in water level is partly canalised rivers, subject to bed erosion, a station for deposit material plunges into the subsoil below the last damming stage. An appropriate mixture of gravel and sand is repeatedly deposited in layers 2-3 dm. thick onto the river bed at the beginning of the erosion sector, to build up a filling up to the level of the original bed, and fed periodically with further material. Current continually removes part, providing bed level stability downstream. The position is of centre bed width, and two or three times as long as this. Erosion resulting in lowering of water level is checked, or reversed if necessary, without provision of further damming stages.