Lake water quality management is an extremely complicated problem due to a variety of land use and existence of multiple stakeholders in the watershed. A decision support tool is thus necessary for examining physical, economical and social constraints associated with the management and for coordinating conflicting goals of the stakeholders. In this study, a multiobjective linear programming model is developed for supporting strategic management of lake water quality. Optimal allocation of river-genetic pollutant load is determined to maximize total allowable load into the lake with in-lake water quality standard. The shallow water equations and two-dimensional COD (chemical oxygen demand) transport equation are employed as basic equations to represent physical constraints on COD concentration. In order to consider an economical requirement on equity, the model proactively controls the difference in share of the total allowable load among influent rivers. An optimization example demonstrates that the methodology developed can produce several noninferior solutions (i.e., load allocations) useful for decision-making in lake water quality management.

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There is few research examples in which the comprehensive water management in the paddy plot with a fish ladder, which connects paddy ponding water and a drainage canal and has a function of run of fishes, is examined considering the water budget in a paddy plot. Hence, the fish habitat and the water budget components were investigated in the paddy plot with a fish ladder. We considered the effects of water management for the enhancement of the fish conservation function of paddy fields on the water budget in a paddy plot. As a result, the increase of the lot management water requirement by the increases of irrigation and runoff drainage induced the expansion of opportunity running from the drainage canal and entering from the irrigation canal and enhanced fish habitat in a paddy plot. The water management for the enhancement of fish habitat, by which the ponding depth is kept at the height of a flashboard set up at the outlet of a paddy plot, will require 1.3-fold irrigation water and yield 1.6-fold drainage water as much as the conventional water management, as an example. Furthermore, we discussed the necessity for a new concept of irrigation and drainage components under the paddy water management considering the fish habitat conservation.

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Nitrogen uptake by crops, green-house gas emissions and nitrogen leaching were studied by using monolith lysimeters applied with digested liquid or ammonium sulfate to evaluate the environmental impacts of applications of methane fermentation digested liquid on Andosol upland field. A two-year experiment indicated the percentages of nitrogen uptake, leached nitrogen and nitrous oxide (N₂O) emissions to each material-derived nitrogen were 27%, 44% and 0.41% in the digested liquid plot and 32%, 46% and 0.11% in the ammonium sulfate plot.
The results show that digested liquid is readily release fertilizer like ammonium sulfate, and nitrogen is leached as easily from the digested liquid as from the ammonium sulfate and the N₂O emissions from the digested liquid plot are higher than from the ammonium sulfate plot.

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While zoning has been practiced to prevent sprawling development and to preserve collective farmland under the Agriculture Promotion Act, The Agricultural Promotion Area (APA) has been reduced in area by the action of the Farm Land Exclusion from the APA (EAPA) aiming at urban-uses. Since the EAPA has a great impact on the regional land use, appropriate criteria application techniques ought to be formulated at the transaction level. However, most local governments seem to have no strategic measure so far. Hamamatsu city, meanwhile, has introduced a unique standard upon which approval of the EAPA aptitude is based in 2003. Since the number of EAPA registration was relatively large in Hamamatsu city owing to the zone bordering on the line of land which a building has erected the officials' willingness to establish an objective standard was high. In this research, we verified the effect of the criteria application over the land use ordering, and made proposals for improvement of the present state through the examination of the EAPA criterion application of Hamamatsu city.

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An inverse method to estimate the unsaturated hydraulic conductivity in seepage flow from field observations is presented. Considering the water movement in soil significantly affected by the soil temperature, the soil column of interest is assumed to be non-isothermal, and therefore the problem is based on coupled 1D water movement and thermal conduction equations. Since the saturated hydraulic conductivity could be definitely known, the inverse problem associated with the unsaturated hydraulic conductivity is reduced to that of identifying the relative hydraulic conductivity (RHC) from the hydro-geological information available. For functional representation of RHC, the free-form parameterized function is employed in lieu of the conventional fixed-form function. Values of the parameters included in the functions are optimally determined according to a simulation-optimization algorithm. For easy application of the method, a utilitarian observation system with simple instrumentation is specially contrived which implements collection of the hydro-geological data relatively easily in-situ available. Validity of the method developed is examined through its practical application to a real soil column in an upland crop field. The results show that the water movement model provides the forward solutions of high reproducibility, when coupled with thermal conduction model and calibrated through identifying the RHC by use of a free-form function.

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Many concrete canal joints fractured during the Niigataken Chuetsu-oki Earthquake. Many of the fractures involved exfoliation of the concrete and cracks that extended from a water stop, and the presence of the water stop apparently affected those fractures. Breaking tests performed with specimens simulating a concrete canal joint were able to reproduce cracks similar to those found in the damaged canals. When cracks occurred in the tests, the concrete near the joint was displaced greatly, causing the specimen to open outward. The water stop was compressed, suggesting that lateral strain or bending pressure at which the water stop tried to bend occurred at the water stop, which forced the concrete to extend. As a result, cracks occurred near the water stop, splitting the specimen.

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There are about 2.8 million ha of inland valleys in Ghana and 20 million ha of inland valley in West Africa. Although inland valleys are suitable for lowland rice due to the abundance of water resources and higher soil fertility compared with the upland, they have not been well utilized as agricultural land in West Africa. Further utilization of inland valley for lowland rice will improve the productivity of rice in West Africa. In this study water resources of small rivers in inland valleys in West Africa are evaluated. Two study watersheds with 1,400-1,500mm of annual rainfall in Semi-Deciduous Forest Zone in Ghana were selected and analyzed on slope distribution in the study watershed to grasp suitable area for lowland rice and on hydrological characteristics such as specific discharge and runoff ratio. The following findings are obtained from the study. 1) Most of the rivers in the study watershed are seasonal rivers. Non-flow period of some rivers were shown for around five months from middle of December to early May. However the term of non-flow period varies much depending on characteristics of sub-watersheds. 2) Runoff ratio for 5 years from 2000 to 2004 in Offinso watershed which is a typical watershed in semi deciduous forest zone in Ghana was indicated only 12%. It ranges from 0.08 to 0.16 depending on the year. The monthly runoff ratio indicated little value in March, April and May which is beginning of rainy season and high value in November and December which is beginning of dry season. 3) The gentle slope area with less than 2%, which seems suitable area for lowland rice, occupies 22 % of inland valley.

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In developing countries, assistance projects to achieve participatory irrigation management (PIM) are implemented. However, benefits from the projects do not always continue. While methods for achievement and factors for continuation of PIM have been studied, judgment of “sustainability” (continuation of the benefits), which is considered in the project evaluation, has not been studied. This paper aims to analyze the present state of project evaluations from the viewpoint of sustainability for eight technical cooperation projects that have been implemented to assist PIM by Japan's official development assistance in the Monsoon Asian Region. Results showed the following: (1) the correlation between each evaluation indicator is not clear. Therefore, an activity for achieving an indicator may unintentionally retard the achievement of another indicator if the people concerned in the project do not adequately recognize the correlation; (2) the existing evaluation guidelines lack fundamental viewpoints for sustainable irrigation management, thus leading to the misjudging of the sustainability of the projects.

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"Stock Management" launched in all over Japan is an activity to use irrigation facilities effectively and to reduce life cycle costs of theirs. Deterioration prediction of the irrigation facility condition is a vital process for the study of maintenance measures and the estimation of maintenance cost. It is important issue to establish the prediction technique with higher accuracy. Thereupon, we established a deterioration prediction model by a statistical method "Markov chain", and analyzed a function diagnosis data of irrigation facilities. As a result, we clarified the deterioration characteristics into each structure type and facilities.

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