A seasonal water balance of the lake Bosten is evaluated based on the calculation of the monthly water budgets during the year of Mach 1983 to February 1984. Details are given of the method to calculate the monthly lake's evaporation and the seasonal pattern of groundwater of the lake. The proportion of seasonal evaporation to the annual evaporation is 35.4% in spring, 33.0% in summer, 19.4% in autumn and 12.2% in winter, respectively. The highest value of the evaporation appears in April and May. On the basis of water balance model, it is found that the water exchange between the lake and the groundwater is sensitive to the activities of agriculture irrigation and the seasonal changes of evapotranspiration in the surrounding region. The lake water supplies the groundwater to the surrounding region during the warm period (e.g. from June to October 1983), and is supplied by the groundwater during the cold period (e.g. November 1983 to May 1984). During March 1983 to February 1984, the annual lake's evaporation was 9.31×108m3, and the annual net discharge of the groundwater into the lake was 0.51×108m3 approximately.

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We analyzed the time response of land surface moisture status and phenology to monitor land surface between the rainy and dry seasons in Thailand. In this study, we used global land 1-km AVHRR data set provided by U.S. Geological Survey (USGS) and meteorological stations data produced by the NCDC (National Climate Data Center). Normalized Difference Vegetation Index (NDVI) derived from multi-temporal AVHRR gave us information about phenology for broad regions. Surface moisture status was represented by the relationship between vegetation index (VI) and surface temperature (Ts) (VI-Ts method). We carried out intercomparisons of the seasonal changes in amount of rainfall, surface moisture status, and NDVI. Consequently, in a transition period from dry to rainy season, we identified time lags among the start of rainy season (124±21 Day of Year [DOY]), surface moisture status (123±53 DOY), and the onset of phenology. From dry to wet in surface moisture status, a noticeable time lag anticipated from the difference of land cover types was not detected, while time lag was found in the onset of phenology in forest (153±43 DOY) and cropland (170±46 DOY). On the other hand, in the transition period from rainy to dry, the time difference in the change of NDVI between forests and crop was noticeable. NDVI in croplands changed rapidly after the dry seasons started, while NDVI in forest changed according to the decrease in the surface moisture status shortly afterwards.

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The exchange speed (CHU) for sensible heat flux is one of the most important parameters for estimating sensible and latent heat fluxes by the bulk transfer method. CHU is also important for estimating soil temperature by using the heat balance model combined with the bulk transfer method. CHU is usually treated as a function of wind speed; however, if wind speed data is not available, it is not easy to estimate an accurate and representative value using measured wind speed from another location due to the effect of the surrounding environment. In this study, we investigated the accuracy of estimating the sensible heat flux over a bare soil surface and its daily mean soil temperature by the bulk transfer method using daily mean meteorological data without wind speed. This means that CHU is treated as a constant value. We also investigated a method of parameterization of CHU on a bare soil without observed flux data. The estimation of the daily mean sensible heat flux without wind speed data has a large root mean square error (RMSE). RMSE without wind speed was 18.3 W m-2, whereas that with wind speed was 10.5 W m-2. However, the accuracy of the estimation of cumulative monthly sensible heat flux without wind speed data was almost equal to that with wind speed data. The two values of RMSE of monthly estimations with and without wind speed data were about 5 W m-2. The estimated cumulative sensible heat flux without using wind speed data, over a period of more than several days, agreed with observed sensible heat flux values. With theoretical analysis and the parameterization of CHU on a bare soil without using observed flux data, the results indicate that cumulative sensible heat flux can be estimated from routine meteorological data without wind speed. The daily mean soil temperature was estimated by the method of Hirota et al. (1995) with and without wind speed data. The accuracy of the estimation of the daily mean soil temperature without wind speed data was almost equal to that with wind speed data. The result indicates that even if wind speed data is not used, the model provides a good estimation of the daily mean soil temperature.

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Low-lying agricultural land frequently encounter severe water quality and drainage problems caused by many factors including stagnation of wastewater, rain and flooding from rivers. The research was mainly concerned with the change of household wastewater quality in drainage canals in accordance with the promotion of small-scale rural sewage systems. The study was conducted in the Hirata Town of Takasu Waju area of Gifu prefecture. Waju is the farming settlement protected by the circular dykes. Hirata town is famous for its sightseeing spot, Ochobo Inari (Shrine), where many people visit, is expected to have pollution from its wastewater. In order to clarify the increase or decrease of household wastewater pollution, we investigated 13 spots of the drainage canals of the study area after considering the inflow and outflow of the drainage water. The daily pollution load of water quality parameters were calculated for each survey month. Results showed that pollution load of community decreased year by year as a result of wastewater treatment plant and near future if utilization percentage increase, water quality in drainage canals would be more improved. However, water quality improvement in the downstream section could not be seen from the past five years data. Countermeasure should be taken to improve the overall water quality in the study area.

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The authors have introduced a new parameter, “jikan-shuchudo” of precipitation. The parameter corresponds to the steepness of the depth-duration line. They have showed the method of estimating the probable 1-hour precipitation by analyzing the parameter. The purpose of this study is to develop the method through which the probable 1-day or 24-hour precipitation can be estimated. Using the AMeDAS precipitation data for all over Japan during 23 years from 1976 to 1998, the parameter was normalized for 10-day precipitation. The probability of the Kochi heavy rainfall in 1998 was evaluated using the proposed coefficient of the normal transformation equation. In order to compare the method herein with the traditional one, they described the procedure how to estimate the annual maximum precipitation at each observing point, and an example was illustrated for Kochi. By applying the method to the AMeDAS observing points, they confirmed that the average relative errors between the measured and estimated values in probability paper are less than 10% against the points of about 84%.

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The 3rd World Water Forum will be held in March 2003 in the Lake Biwa-Yodo River region of Japan and the role she is to play as a host would be an extremely important one. The World Water Vision adopted in den Haag in March 2000, that broadly encompasses such major issue domains as “Water for People”, “Water for Food”, “Water and Nature”, “Water in Rivers” and “Water and Sovereignty”, is again to be brought for elaboration. This time the major subjects of discussion should revolve around implementation of the Vision that would include specific financial and technical issues. In addition, there are issues that were more or less left for further disputes such as “commodification of water” and “privatization of water undertakings”. Further, there are subject areas lying across these Vision issue domains that were not really adequately elaborated in the 2nd Forum. In particular, many of the world's lakes and reservoirs are caught between development and conservation and are facing serious degradation because of the difficulties associated with resolving the gaps among the specific visions. Hopefully, there will be in-depth discussion leading to development of a vision which will form a useful basis for coming up with“ the principles for action” for better management of the world's lakes.

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