It is an important subject to evaluate sediment transport bubfet in river management works. In this paper sediment transport output from the Ishikari River is investigated as primitive example for this subject. Relationship between turbidity data and suspend sediment concentration data is investigated and a formula to evaluate wash load transport rate is proposed. Using the daily discharge data of the past 20 yeas, the annual sediment runoff from the Ishikari River mouth is calculated. The annual runoff of the bed material is also calculated by a numerical model for bed load and suspended load transport, bed deformation and grain size distribution of bed material. The results of wash load runoff and bed material load runoff are compared and it is found that wash load runoff can be explained as a part of bed material load.
This paper presents an attempt to apply the weekly weather forecast data for a snowmelt runoff prediction. The basin is 1.0km2 in area and elevation ranges from 390 to 800m above sea level. The snowmelt model makes use of digital terrain data with 20m grid spacing. Energy balance components are calculated for each grid element taking topographic variations of solar radiation into account. In ordar to use the snowmelt model in the forecast situation, it is necessary to predict the meteorological data for any future time period. In this study, 1) the insolation is calculated by the forecasted percentage of sunshine, which is divided into 15 weather conditions; 2) and the temperature is calculated as a function of time elapsed. One week ahead forecasting results by the snowmelt runoff model using the weather forecast data are accurate enough for practical purpose.
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