SEDIMENT AND NUTRIENTS TRANSPORT IN THE HINUMA RIVER AND ESTUARY

Abstract

Suspended sediment and nutrient transport were monitored during one year in two areas, one is the upper reach of a river which flow into Lake Hinuma, one is the estuary which is outlet of the lake. SS and particulate phosphorous (P-P) concentration can be estimated by turbidity using their correlation. The measurements of suspended load in the tidal channel were made using an acoustic Doppler current meter and turbidity meters. The amount of the sediment which is the difference between the sediment load monitored in the river and in the tidal channel during one year corresponds to the annual sedimentation rate in Lake Hinuma which was estimated by geological approach. The flux of P-P flow into the lake during floods reached 60% of the total phosphorous in one year. It is assumed that most of these P-P deposits in the lake and dissolved phosphorous released from P-P makes phytoplankton grow up.