It is very important to estimate amount of sedimentation in dam-reservoirs in order to make full use of dam-reservoir's capacity economically. Based on accumulation of long series data annualamount of sedimentation in dam-reservoirs and long series meteorological data, and various kinds of numeric data which figure characteristics of catchment areas, correlation detween annual specific amount of sedimentation and some factors related sedimentation is analyzed. To fit annual amount of sedimentation to stochastic process is tried. It is clear that distribution of annual amount of sedimentation is treated as logarithmic normal distribution or Gumbel distribution. And then, a new method to estimate the sedimentation capacity in dam-reservoirs, which involves stochastic approach using precipitation data, is proposed and it's accuracy is verified.

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Roller Compacted Dam Construction method has been used for gravity concrete dam construction as a major method in Japan. Quality of RCD concrete depends on materials, especially fine aggregate.
Therefore severe selection for materials and strict quality control has been done on fine aggregate. Low quality aggregate should be adopted for the concrete dam construction in order to keep source of aggregate, if quality of concrete can be kept.
According to recent studies on the normal concrete, milled stone has been recognized as on excellen additional material to improve behavior of fresh concrete such as workability so on.
The Double Mixing method (which was expected enveloping sand with cement) was also assessed to reduce the bleeding of concrete and to improve quality of concrete.
The authors assessed quantitavely the effect of improvement of RCD concrete by these methods in laboratory test. It was observed that bleeding was considerably reduced and that workability was also improved by adding 30kg/m³ of the milled stone instead of fine aggregate. Quite similar tendency was observed by the Double Mixing method expected to sand enveloped with cement.

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In-situ investigation was carried out before and after grouting in rock mass, using crosshole seismic waves and elective magnetic waves. The grouting effects, (size of improvement zone and characteristics of rock mass) were estimated.
As the results, the followings were concluded. The zone that cement milk permealed was estimated from change of electric magnetic wave attenuation. There was a relation between a permeability of rock mass and velocity or attenuation of electric magnetic wave.

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Asphaltic concrete are used for sealing earth and rock fill dads or upper reservoirs of pumped storage schemes, as impervious facings and cores.
Asphaltic concrete has been used for such a facings for about 25 years and over 20 dams (involving reservoirs) with asphaltic concrete facings have been constructed by the end of 1991, in Japan.
The authors have investigated for the study of the properties of the materials, adequate mix proportions, the mechanical properties of mixtures, application to designing and construction methods for asphaltic concrete facings of fill dams.
In this paper, the authors intend to discuss mainly the mechanical properties, designing and constrction of asphaltic concrete facing.

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“Drawdown zone” of dam reservoir, repeating submerged and dried conditions, often remains a trip of exposed zone. Since such slope surface without any treatment is not preferable from the standpoint of slope stability as well as natural landscape, the slope protection with vegetation in harmony with the surroundings is desired. In this study, suitable plants for both submerged and dried conditions and the treatment method are investigated based on the field survey and the nationwide questionnaire survey of existing dams. The fundamental procedure of planting treatment for exposed reservoir shore is proposed.

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We present the application of Electrolysis of using Aluminium Anodes for treatment of turbid water by civil works in site of ZUKEYAMA DAM in OKINAWA, and base study of Electrolysis of using Aluminium Anodes for treatment of turbid water by Technical Reserch Institute of our company.
We hope to take the low cost, safety, and easy maintenance turbid water treatment system in this study.

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