Development of a Model for Analysis of Suspended Soil Density

Studies on modeling of runoff of reddish soil in Okinawa

Abstract

In Okinawa, there is a need to forecast the density of suspended soil in river water after land reclamation. The purpose of this study was to develop a model for the analysis of suspended soil density.
In this study, surface water flow is first calculated using a kinematic wave model. Next, models for analysis of suspended soil density, which include the LQ equation, Meyer's model and the model developed in this study, are incorporated in the calculation of surface water flow. The data used in this study was obtained from fields subject to severe erosion in the north of Okinawa island.
The results obtained are summarized as follows:
(1) It is assumed that values of the equivalent roughness of the catchment area in the kinematic wave model differ according to the scale of runoff, in the case that surface water flows in gully.
(2) The simple LQ equation is not suitalde for analysis of suspended soil density.
(3) In application of Meyer's model, it is assumed that amount of eroded soil is affected by the sediment carrying capacity of flowing water when the land is easily eroded.
(4) In was confirmed that the model developed in this study is suitable for calculation of the density of suspended soil, when the quantitative relation between the parameter values and the condition of soil and field are known.