Study on dispersion coefficient of surface flow in Zhaidi underground river basin in Guilin City,Guangxi Province

Dispersion coefficient is an important factor in studying the impact of accidental pollution event in rivers on ecology and human beings.In order to obtain the dispersion coefficient of Zhaidi underground river,tracer test was conducted in open flow reach of the river.The electrical conductivity and chloride ion contents of flow were measured at downstream 21 m,585 m,960 m and 1 385 m of tracer dropping points.The study on measured data by analytic method show that the average flow velocity and dispersion coefficient of the open flow reach of the river are respectively 0.137 m/s and 0.227 2 m/s.