摘要:Form of tidal river cycle and determination mdthod of water qualities were investigated at the tidal areas of river ran with industrial waste and domestic sewage, and the following results were obtained. 1. Direction of tide is changed by branching and by curve of river. 2. Stay of polluted substances could be removed by controlling discharge of waste water and sewage according to the direction of tide. 3. In the case of wide river containing sea water several sampling points must be settled across the river and aliquats from both upper and lower layers should be drawn out as test samples in accordance with water depth. 4. In the branches of tidal river no increase of chloride was observed at high tide, and this seemed to be check phenomenon by main stream.