Abstract
The domestic wastewater flows into urban small rivers and it pollutes water quality of the urban small rivers. Especially the untreated domestic wastewater from the catchment area with no sewerage works influences water quality of the urban small river significantly.
This paper deals with an estimation of improvement in the water quality of urban small river by treatment facilities of the domestic waste water with the mesh analysis model. The mesh analysis model can estimate flow rate, flowing pollutant loads and water quality in any cross section of the river. The mesh analysis model can estimate changes of flow rate, flowing pollutant loads and water quality by urbanization, sewage works construction, settlement of household wastewater treatment tanks, which purify sewage and domestic waste, and etc.
And the mesh analysis model represents a reduction in the pollutant loads by self purification with runoff rate of pollutant load between a mesh and the next mesh. We estimate an effect of construction of sewerage works and arrangement of the household wastewater treatment tanks for improvement in water quality of Sanda river. The concentration of pollutant load is reduced by the constraction of sewerage system in downward of the catchement area and the amount of pollution load decreases from 1/3 to 1/2 of it before sewage works construction.
