Erodible volcanic ash soil widely covers land surface in eastern Hokkaido. In this area farmland reclamation projects, including construction of farm roads and surface and subsurface drainage, have taken place over the past 30 years. Large areas of forest and wilderness have become farmland, therefore reducing erosion becomes an important issue. Increasing erosion may be caused not only by the decrease of vegetation in winter, but also the change of runoff mechanism. Therefore, we carried out a series of research to control suspended sediment discharge at drainage river in the Memanbetsu river basin, where many farmland reclamation projects had finished. As the first stage of the researches, we analyzed daily discharge data over a long period in the basin using filter separation auto-regressive method. As a result, it was proved that the expansion of farmland makes the shape of response function sharper and the distribution of interflow larger. In consideration of those phenomena, we proposed a Nash's assembly model composed of two components i.e. interflow and groundwater flow, and verified its reproducibility. This model is simple. We can calculate runoff by substituting only the separation percentage of effective rainfall for the components' input values which represent the degree of development in each sub-basin. Our model is capable of predicting runoff changes resulting from development of basins, controlling runoff and estimating sediment load by substituting the calculated discharge into the relation equation between discharge and sediment load.

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Nitrogen discharge during snowmelt period from the river with agricultural watershed in Hokkaido, Japan was examined. Snowmelt period itself was divided into early stage, active stage and late stage. In early stage of snowmelt period, the dissolved nitrogen concentration was higher than other stages, but the particulate nitrogen discharge was lower. In active stage of snowmelt period, the concentration of dissolved nitrogen, which is eluvial ingredient, show decrease during daytime. But its load shows no daily fluctuation, and show the long-span fluctuations that corresponded to the flow rate during the stage. Surface runoff component of dissolved ingredient is relatively high in both concentration and load during daytime. For the long time span, the load is relatively stable, while the concentration tends to decrease. The particulate nitrogen discharge shows high concentration with increase of flow rate and SS concentration. Diurnal tendency of component discharge during late stage of snowmelt period is quite similar to that of active stage. Through this stage, concentration level of dissolved nitrogen was lower than that of active stage, which indicates decrease of accumulated storage in the watershed. Surface runoff component of dissolved nitrogen, and whole particulate nitrogen decrease both on concentration and load through this stage.

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There are two main observation systems of precipitation in Japan. One is manned surface meteorological observation system (hereafter, we refer to this system as 'Surface observation') that consists of about 150 observation stations, and the other is 'AMeDAS' (Automated meteorological Data Acquisition System). The former system has the advantage that observation period is relative long, while the latter has the advantage that spatial resolution of the system is fine. The authors investigated on two issues. First, we examined the presence of adequate correlation between two systems from the viewpoint of annual precipitation. Secondly, we examined the validation of annual precipitation over Japanese whole domain, which is estimated by 'Surface observation' data or 'AMeDAS' data. As a result, we conclude that 'Surface observation' data is enough correlated to the neighbour 'AMeDAS' data, if the distance between two observation stations is less than 100km, that is, we can use 'Surace observation' data as the values that represent neighbour region's precipitation. Moreover, we obtained results as follows; 1) the change of whole domain's precipitation estimated by 'AMeDAS' data shows more increasing tendency than real tendency, because 'AMeDAS' data is not homogeneous, namely, the mean altitude of observation stations of 'AMeDAS' is increasing; 2) the whole domain's annual precipitation estimated by 'Surface observation' data is an approximation from the viewpoint of the tendency of annual change, though we have to know that the estimation is much less than the real value; 3) although the whole domain's annual precipitation estimated by '46 point data' that is often used by civil engineers shows relatively same tendency as the whole domain's annual precipitation by 'Surface observation' data, the quantity of annual precipitation is quite underestimated

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Involuntary resettlement has become the largest issue in dam construction projects. Provision of farmland as substitute of the lost land is a most appropriate way of compensation, as long as (a) resettlers wish to remain farmers after relocation, and (b) lands to be given to resettlers are available. In case provision of farmlands is not feasible, resettlers are obliged to change their occupation. Re-establishing their living with new jobs is in general difficult and accompanies many uncertainties. The existing policy of compensation for resettlers does not have a provision to deal with such difficulties and uncertainties. The success of aquaculture in Saguling and Cirata reservoirs has been praised, for it has provided resettlers with new jobs and better earnings. However, most of resettlers did not in fact have sufficient funds to commence aquaculture. License to put fish cages on these reservoirs have not been properly managed by the authority to the extent that resettlers could benefit most out of aquaculture. Very small number of resettlers obtained jobs in dam construction related works. Few benefits of the secondary development was enjoyed by resettlers. Some mechanism should be established so that resettlers could be taken care of, in terms of their reestablishing living, even after completion of a dam construction project. Establishment of a fund both for inundated and surrounding areas ought to be a viable option, which may also contribute to preservation of the environment around the project site.

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In order to estimate evaporation and water uptake by pseudo-roots, pressure heads in the soil column were measured in detail. An undisturbed soil column (20cm in the diameter and 60cm in length) buried with pseudo-roots was used. In the analysis, we divided the column from the top into six layers at intervals of 10cm. The amount of the decrease of volumetric water content in each layer was evaluated by using soil moisture characteristic curve. In consequence, the sum of the decrease of volumetric water content in each layer was in good agreement with the loss in weight of the soil column. Evaporation from the top surface of the column was evaluated as an amount of decrease of volumetric water content in the 1st layer. Water uptake by pseudo-roots was evaluated as a sum of the decrease of volumetric water content from 2nd to 6th layers of the column.

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The 2nd World Water Forum was held in The Hague, The Netherlands in March 2000 and the “World Water Vision” for the 21st century was launched at the Forum. After that it was decided that the 3rd World Water Forum would be held in Kyoto, Shiga and Osaka, Japan. Subsequently various activities related to water have been initiated around the world. This article deals with the world water issues and global movements towords the solutions of these issues as well as Japan's role and preparatory activities in making the 3rd World Water Forum a success.

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The security issue of the international water systems is of importance for many people in this world. After years of UNU's working on international water systems, some perspectives has been identified. These perspectives are new for many researchers and practitioners, while looking at the issue of international water systems from these viewpoints will sure to lead to more solid strategy and policy in dealing with transboundary water issues. This synthesis was developed to identify these new perspectives as the research subjects on international freshwater systems for the UNU's 2002-2003 workplan. The research subject were selected according to the following criteria: (a) a subject should be new and innovative, (b) the UNU should have a leading role in promoting research activities on a subject, (c) the experiences and expertise accumulated through the previous academic activities of the UNU should be fully made use of, (d) the existing “academic connections” such as the network of researchers so far developed and maintained by the UNU should be mobilized to the extent possible, and (e) some visible results should be obtained in less than two years with fairly small funds provided by the UNU. The following four research subjects have been identified for the UNU's activities on international water systems for 2002-2003: (a) Implications of real and virtual trade of water resources, (b) Lakes as international water systems-World Lake Vision development, (c) Power of Information Disclosure and Public Participation, and (d) Impacts of “Domestic” Security Issues. The above mentioned new perspectives will hopefully be implemented in the next biennium of 2002-2003 as specific academic activities.

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