Observation of total load in upstream of the Abe river

Abstract

To resolve the problems resulting from sediment discharge, it is required to treat the entire area of sediment as the “sediment transport system”. To enable this, the actual state of sediment discharge must be grasped. In the case of mountainous rivers, it is desirable to trap sediment discharge at all depths, because bed load and suspended load and washload flow down being mixed. We developed the Total Load Trapping Equipment that can trap all sediment discharge passing through the overflow section at the unit width. We placed it at the Oshima check dam in Abe river and measured the sediment discharge. Based on the observations, the sediment discharge was quantified by sediment movement type and the following knowledge was gained; (1) In the case of floods of normal year scale, suspended load plus washload account for a far greater ratio than that of bed load in the total sediment discharge flowing down a mountainous river ; (2) The suspended load plus washload obtained at this river was greater by one order than those obtained at other rivers; (3) The bed load estimated by the Ashida, Takahashi, and Mizuyama's formula was greater by 3-5 orders than the measured amount in many cases, but the difference was within 1-2 orders in some cases obtained at peak flow rate. The bed load estimated by the Meyer Peter, Muller's formula was generally smaller than the measured amount, but the difference remained within 1-2 orders.