We have carried out the bench-scale experiments and the simulations on Bottom-Filtration for improvement of water quality in eutrophic lakes. “Bottom-Filtration” means filtration of lake water through the filter which is installed on the bottom of the lake, and the filtrate is circulated to the lake water. In the experiment we used decomposed granite and Kuroboku Soil (Ando soil) as the filter media. And circulation rates were set as no circulation, 14 days and 3.5 days. We found that water quality becomes finer as higher the circulation rate, but the filter media do not show much difference. Introducing mass transport by convection to the filter, we remake the Water-Sediments Eutrophication Model, and have carried out the simulation. The results of the experiments and simulations show quite good accordance.

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RCD is lean and dry mix of concrete which is compacted by vibrating rollers. In order to place workable concrete without honeycomb void or entrapped air, a certain amount of paste is necessary. This paper studied the amount of paste to make RCD workable. The test was carried out by changing in cementitious material-water ratio of RCD. The result shows that required paste volume is the function of cementitious material-water ratio and that the richer cementitious material-water rate is, the more the required paste volume is.

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In Japan, the design sediment capacity of a dam has been set in plans of flood control dams since 1950's. It has been generally determined on the basis of an estimated volume of sediment accumulated for 100 years. The sediment monitoring has been performed systematically at many dams since 1967. But, there are not so small gaps between the observed volumes and the designed ones that were estimated by several estimation methods proposed previously. To solve these problems, an empirical estimation method is developed for reservoir sedimentation based on sediment inflow. It is named Sediment Yield Potential Map. With this map, we can calculate the amount of sediment inflow precisely at any point easily. The map is processed from the statistic relations of the sediment inflow which is modified from the actual sediment and the influence factors about geography and geology. And it is showed on a chart by GIS.

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Most of irrigation reservoir dams were mostly accumulated with a mud soil in reservoir that caused the pollution and the shortage of reserved water. This mud soil generally is high-water-content and very soft clayey soil. In order to make efficient use of such a problematic soil as embankment soil, we have developed a new type method to repair the deterioration embankment by means of the stabilized mud soil with cement stabilizer. This paper investigates geotechnical problems when applying this method to repair the embankment of the earth dam having the embankment height higher than 15 m.

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WTPs derived from CVM are different when people have different participation minds to projects. In this paper, the reasons for the differences are analyzed by measuring WTPs and evaluating the attributes of the samples of the CVM test. The participation minds are expressed by paying funds to the project, paying income taxes, and participating the project as volunteers. As a result, the group who are willing to participate as volunteers show the WTP which is about one-third of the WTP shown by the group who are willing to pay funds. Under the conditions that about 30% of the whole samples want to participate as volunteers, it should be dangerous to execute the CVM test without considering explicitly differences of the attributes of the CVM samples. It is strongly recommended that before executing a CVM test the samples' participation minds and their attributes are to be analyzed and well understood and that if a voluntary mind is dominant in the samples CVM is not good enough to evaluate a project.

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