A Preliminary Study on the Chemical Composition of River Water in the Flood

Abstract

On the chemical composition of river water, it has been accepted that an increase in water level is mainly accompanied by a decrease in concentration of chemical composition. Looking over the state in concentration change of river water in high water level, however, the chemical composition does not necessarily indicate such a trend.
As for observations at Oyahana of the Ara River during the flood (6.30 m in peak) occured by Typhoon No. 14 in 1954, writer the made clear that Ré (Solution), SO ′′₄, SiO₂, PO′′′₄, varied in proportion to the water level. This phenomenon might be explained by the fact as follows. 1) The soluble materials of cultivated field and weathering soil were washed away by the hard surface runoff, when the land got a shock by the heavy falling rain drops. 2) The soluble materials of suspended load in river was washed away by the flow, when the suspended load was stirred up by a strong force of turbulence flow.
The total amount of chemical composition transported by the river during the flood was also estimated 15 × 10³ t in Ré (Solution), 5 × 10² in Cl′, 9 × 10² t in SO ′′₄ 13 ×10² t in SiO₂, 2 t in PO′′′₄, respectively. Amount of Solution corresponds to some 1/40 to amount of suspended load simultaneously transported.