现有的小型水库、山弯塘的放水设施，多采用横穿大坝下的放水涵洞与库内的石质放水卧管组合而成，其放水卧管上的放水孔，多采用石塞或木塞加水泥堵水，弊病较多。后有少数水库在放水卧管下端与放水涵洞交接处修建一竖井，人可进入竖井，在库水面以下放水。实践证明，此法投资 The existing small reservoirs, mountain curved pond water diversion facilities, and more use of the drainage culverts across the dam and the reservoir within the stone drainage pipe combination made of the diversion hole on the water pipe, the use of more plugs or Cork plus cement block water, more ills. After a small number of reservoirs in the lower part of the water pipe and drain culvert at the junction of the construction of a shaft, people can enter the shaft, the water below the reservoir surface water. Practice has proved that this method of investment