Amounts of Suspended Solids and Elements Transported Annually from the Takahashi River (Japan) to Estuary

Abstract

Concentrations of suspended solids and discharges were measured in the period from 1975 to 1980 in the Takahashi River system (111km long, 2670km2 drainage basin). The sampling site was 10.4 km up the estuary, where the riverbed averages 0.73m above sea level.
When the flux of suspended solid (g·sec^-1) and the discharge (m3·sec^-1) were plotted on Y axis and X axis, respectively, the relation Log Y=2.02 Log X-0.83 (n=75, r=0.94) was found. By substituting the regression line for the daily average discharge, the flux of suspended solid (g·day^-1) was estimated. When the discharge increased very greatly as a result of heavy rainfall between June 29 and July 1, 1979, its amount (g·hr^-1) was estimated by substituting the above regression for the hourly average discharge. Thus, the amount of suspended solids transported during 1979 from river to estuary was estimated at 75×10⁶kg·yr^-1 (discharge : 1976×10⁶m3·yr^-1), while the amount for the day of June 29 reached 28×10⁶kg·day^-1 (or 37% of the total).
A comparison between the average daily concentrations of elements and their concentrations on the June 29th heavy discharge day was undertaken to fully appreciate the effects of heavy rains.