Many sabo structures; dams, groundsills and embankments have been constructed in mountain areas. Some of them are hated because white bright surfaces of new structures dismatch with natural surroundings. To add dyes to concrete and to make ruggedness on the surfaces are examined to reduce the brightness and to hermonize sabo structures to their surroundings. Elements controlling results are picked out and evaluated through experiments. The methods give good results. Darker surfaces and not too much contrast get good reputation. These methods are applid to a sabo dam as an example by a photo montage methods.

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せん断抵抗強度を使用して, 多平面安定解析(沖村1982) を行ない, 「擬安全率」を求め, その擬安全率を使用した解析により以下の結果を得た。
1) 6サンプル地区の各斜面について崩壊・非崩壊の区分が実際に生起した崩壊事例と一致するように, 斜面の集水面積(S) , 潜在崩土層の厚さの関数(γ) を変数として擬安全率の値に関する判別関数を求めた。求めた斜面毎の判別関数の値は, 「限界擬安全率」となり, 適中率は73%～100%となった。
2) 3サンプル地区でせん断抵抗強度値は30%変化させても, 各斜面の崩壊・非崩壊の判定結果には1地区の2斜面を除き変化はない。また, そのときの各斜面の「崩壊得点」(=(限界擬安全率-擬安全率) ×100) の変化は, 絶対値平均で1. 8～2. 5となった。このことは, せん断抵抗強度値に拘らず崩壊・非崩壊を判定できることを意味する。
3) 各斜面に, それ以上の降雨があれば崩壊が起こるという「限界実効雨量」を定義できる。その限界実効雨量をS, γ, 擬安全率をパラメータとして求めた結果によると, 限界実効雨量決定の誤差は8%程度になっている。

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A sediment related disaster occurs frequently in rainy seasons in Japan. In this study, pressure heads in the soil were measured at 10 points on the hillslope consisting of weathered granite to get fundamental data to explain the behaviour of rainwater on a forested hillslope and the mechanism of hillside landslides. The observed suction for natural rainfalls was reproduced by a numerical model that estimates the process of infiltration as a vertical unsaturated seepage and a parallel saturated flow along the slope.
Following matters were found by this study.
(1) Drying and wetting processes of soils step forward to deeper layers from the surface.
(2) The arrival time of rainwater to the bedrock decreases with a decrease of the depth of soils.
(3) In the initial stage of rainfall, a large amounts of rainwater are temporally stored in the weathered surface layer that contains organic matters. And, it reaches the bedrock layer gradually as the time goes.
(4) Comparison of the observed and calculated soil-moisture content showed that this simulation model is adequate for reproducing the arrival time and the infiltration process, of rainwater.

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Sabo dams have not had sediment frash gates. Sediment control functions of ordinary sabo dams snd slit sabo dams are limited. One of the methods to improve sabo dams is to install sediment frash gates to them. The feasibility of the installation is examined from the structural view point. The result is; it is possible. Some specific gate types and locations of the installation are recommended.

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