Abstract
The River Uji merges with the R. Katsura and R. Kidu at the same point and then becomes the Yodo River. We observed the Yodo River every three days at three transverse points and the other three rivers weekly at their downstream points, and estimated the runoff loading balance of Cl- during their flow downstream. The runoff characteristics of Cl- in the rivers and the detailed input and output loadings during the flow of the rivers downstream were clarified. By computing the Cl- loadings of the rivers outside of the observation periods using the regression equations between flow and loading, the mean Cl- loadings for one year were estimated and compared with the total mean Cl- loadings of the three upstream rivers and that of the Yodo River. By estimating the discharged Cl- loadings for one year for the watersheds of the rivers using the statistical data of the consumption of salts and the watershed characteristics and by comparing the estimated values with the values due to the regression equations and observation data, it was confirmed that the basic discharged loading method of Cl- can be applied to the analysis of the large watershed of the Yodo River.
