We studied the properties of the ground surface temperature and the exchange speed CHU (reciprocal of atmospheric resistance) on bare soil. These are both important factors for estimating the sensible heat flux by the bulk transfer method. The ground surface temperature is difficult to observe accurately in the daytime because a large temperature gradient often exists near the surface and the landsurface properties are inhomogeneous. On the other hand, the daily mean value of ground surface temeprature is not difficult to observe because it is not sensitively dependent on the soil depth and it is not sensitive to inhomogeneous properties of the landsurface. We explained the features by using the Force-Restore Model (FRM) which has been developed for simple prediction of the ground surface temperature. According to the FRM, the surface layer thickness for the ground surface temperature is affected the damping depth that is the function of not only the thermal diffusivity of soil but also the period. With regards to the exchange speed CHU, we obtained almost the same results between CHU calculated from 30 minutes averaged value and CHU calculated from daily mean value. If the soil surface is sufficiently wet, the exchange speed CHU can be estimated by using daily mean values obtaibed from routine meteorological data without needing the observed sensible heat flux. We estimated the daily mean value of sensible heat flux well by using routine meteolorogical data. The root mean square error was about 10 W·m-2.

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As a counter measure for declining safety of water supply system, recent efforts are focused on an integration of water resources and related facilities into an unified network system. In order to realize such system, quantitative evaluations of real capacities for water supply of individual communities are indispensable. In this respect, two local communities with different characteristics inherent to the water supply systems are studied by analyzing their risk against drought. The risk indices evaluated for two communities are reliability, resiliency, vulnerability and Drought Risk Index (DRI) of the water supply systems. The following remarks though the risk analysis under various scenarios are obtained; (1) A risk analysis is useful to characterize the water supply system. (2) By knowing what individual communities should do for increasing safety of water supply system. (3) Amount of water to be shared can be calculated. (4) It is appropriate to analyze the risk for the evaluation of water supply system. And this evaluation should be done for a feasibility study of an integration of water supply systems.

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Implication of a dam construction project on human settlements has been a matter of dispute, for such a project usually involves involuntary resettlement of residents. However, in terms of EIA (Environmental Impact Assessment), no established methodology exists to properly deal with human settlements. It is therefore urged to evaluate the performance of existing EIA methods, so that more sophisticated methodologies could be developed. This study deal with the construction project of the Saguling Dam, in Java island, Indonesia. Despite the fact that the EIA for the project was conducted in late 1970's to early 1980's, when the EIA methodology itself was still in its early stage of development, the EIA method applied was very well designed. This study took steps of (i) compare what the EIA report predicted with what actually happened, (ii) find out reasons behind the discrepancies observed, and (iii) elaborate recommendations to improve the methodology. The study reviewed the EIA methodologies applied from the view point of improving their capabilities to deal with human settlements. Following aspects were not properly dealt with in the EIA: (i) collapse of community, (ii) lack of proper information, (iii) distrust among residents, (iv) employment by the construction project, and (v) compensation for resettles. Recommendations are made for refinement of the methodology to better deal with these aspects.

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A hydrological process within a soil layer on a hillslope containing widely-developed preferential pathways was modelled in order to understand effects of slope properties such as soil physics on runoff from the hillslope characterized by various kinds of heterogeneities. A network of the preferential pathways on the impermeable layer was assumed to efficiently drain the discharge (QV) downslope produced from the bottom of the soil layer to which two-dimensional saturated-unsaturated flow was applied. A large difference was found in recession properties between QV and QL, the discharge produced from the downslope end of the soil layer through a lateral unsaturated flow in it. A comparison of the recession properties with those of runoff monitored in a small study catchment showed that QV decreased much more quickly than the observed stormflow although the recession of QL was similar to the observed baseflow. It was suggested that QV and QL could contribute to stormflow and baseflow, respectively, considering that some time-lag given by downslope flow within preferential pathways must be added to QV. Functional relationships were detected between each of the runoff components (QL and QV) and water storage integrated in the soil layer. These relationships might promote a parameterization of slope properties to runoff models.

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At hot, dry soil surfaces, water vapor density increases sharply from under the ground to the surface air layer, although the vapor moves upward across the surface against its density gradient. The machinery by which the counter-gradient flow of vapor occurs seems to be a kind of convection which is driven by the large temperature difference between the soil surface and the air next to it. More work neeeds to be done, however, to clarify the way these characteristic vertical profiles per se are produced. It can be inferred from these results that the rate of evaporation from bare soil during its third stage is controlled by the profiles of soil water and temperature, and is scarcely influenced by the humidity and wind speed in the surface air layer.

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We investigated the water quality of Ishikari river, the longest river in Hokkaido, during a snow melting season. The results are summarized as follows:1. Changes of water quakty during the srow melting period. (1)During periods of rising water in snow melting seasons, the concentrations of particulate components, especially SS, TO Css, PP etc., usually increase. (2)The concentrations of BOD, TOCF and inorganic anions decrease as the water runoff increases, and the supply of these components from the surface seems to be limited, which tends to be remarkable in regions influenced by growth of the urban communities. (3)The accumulation of nitrogen, mostly as nitrate ions, is limited and nitrogen concentration in the late snow melting period is low. A large amount of phosphorus accumulates in soil and it runs off as a form of suspended phosphorus at high concentrations. (4)From PCA analysis, the run-off pattern of chemical components in this season is classified into three stages: dilution of pollutants (the early stage), outflow of pollutants originating from non-point sources (the middle stage), and outflow of non-pollutants (the later stage).2. Run-off characteristics of chemical components during the snow melting period. (1)The proportion of water flow during the snow melting season is nearly 30% of the annual average. General inorganic components are near this proportion, but pollutants are under 30%. Especially, the proportion of soluble organic components is small. The proportion of inorganic nitrogen is higher than 30% in urban watersheds. The run-off characteristics of chemical components are closely related to the pollution characteristics of the watershed. (2)Run-off in the snow melting season has less ability to flow out of the surface soil than during floods.

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In this study, we made a spectral sensor which is composed of a photometer and a metalhalide lamp to monitor Microcystis. The photometer is made of nine photodiodes and three interference filters(550, 670, 800nm). Absorbance of some water samples;Microcystis, Spirogyra, Andosol and Magnesium oxide; were measured in laboratory using the sensor. The results show that the absorbance of Microcystis and Spirogyra is similar to the one of land plants. Therefore, concentration of these phytoplanktons will be estimated by difference of absorbance of 800nm and 550nm. Microcystis and Spirogyra are classified using the specific feature of Phycobilin. Phycobilin, which is characteristic pigment of the bluegreen algae, is not contained in Spirogyra but in Microcystis. Since Phycobilin absorbs electromagnetic wave in 500-650nm, the absorbance of 550nm significantly increases with increasing of concentration of Microcystis. As abovementioned results, following steps to measure Microcystis are derived. First, divide phytoplanktons and others by the difference of absorbance of 800nm and 550nm. Second, divide the blue-green algae and other phytoplanktons by the difference of absorbance of 670nm and 550nm.

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