抄録
Water quality deterioration in lakes is caused by social and economic factors. For future water environment preservation it is necessary to analyze integratedly the constituents of the catchment area and to structurally remove the cause of water pollution. The method of total management of the catchment area was studied here about Lake Teganuma.
The catchment area of Lake Teganuma was divided into 168 small sections, and multiple relationships among information such as land utilization, population density, extension rate of sewerage and effluent load of chemical oxygen demand, total phosphorus and total nitrogen were examined.
High multiple relationships with correlation coefficients of 0.924-0.997 were obtained among the effluent load density of chemical oxygen demand, total phosphorus and total nitrogen, the population density using onsite small scale nightsoil treatment facilities and those using nightsoil treatment facilities. And high multiple relationships with correlation coefficients of 0.630-0.867 were also obtained among the effluent load density, the total population density and the extension rate of sewerage. These reflected the fact that the major constituent of effluent load to Lake Teganuma is domestic waste water. As the result, sections where water purification measures should he preferentially taken could be grasped.
In order to solve this problem fundamentally, it is necessary in future to manage synthetically the catchment area, that is, to review the present sewerage system planning and the present land utilization planning including city planning.
