2006 Volume 48 Issue 2 Pages 101-111
The flow rate and water quality of a s p ring were monitored continuously for two years in western Saitama Prefecture. Precipitation resulted in a marked increase in the groundwater level and flow rate of the spring with nitrogen-nitrate concentration. The combination of farming as the dominant land use type and a shallow water table in the area were considered to be responsible for the supply of soluble compounds such as a nitrogen-nitrate to the groundwater. The concentration of nitrogen-nitrate in the groundwater was closely related to the frequency and amount of fertilizer application. Simulations of flow rate and water quality were conducted for the spring using a groundwater tank model describing the daily decrease of fertilizer in soil. The findings revealed that the movement of soil water due to rain infiltration was responsible for the daily fluctuations observed in spring water quality.