The effect of global warming on the dissolution of limestone was observed by using numerical simulation. The examination is related to the stability of the underground dam constructed in the south islands in Japan. The model includes dispersion/diffusion, advection, ion exchange, formation of complexes in the aqueous phase, and the dissociation of water and chemical precipitation. The mass action, transport, and the site action equations are expressed in a differential/algebraic form and solved simultaneously by FEM. Results revealed that the physical effect of global warming was very small but considering the detailed investigation of each parameter, lowering of pH has greatest influence on dissolution of limestone, followed by increase in temperature. As the acidification of the rain water progresses, the dissolution of limestone increases. As a result, underground soil porosity increases so that more water will be stored in the aquifer. Increase of intensity of rain, which coincides with the increase of velocity of inlet water, caused the decrease in the dissolution of limestone compared to reference. Dissolution of limestone was favored with increasing temperature as a result porosity of underground dam also increased. Dissolution of limestone increased with combined change of pH, velocity and temperature so that porosity also increased.

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Irrigation plays a significant role in the path of agriculture development with its consequent effect on the progress and livelihood of agrarian-based society like Nepal. Majority of the irrigated areas are served under Farmer Managed Irrigation System (FMIS). This study is carried out to determine the socio-economic, demographic factors influencing satisfaction of the users in the Kumroj Farmer Managed Irrigation System (KFMIS) regarding water availability in plain area of Nepal, using the farm household survey data collected from 100 beneficiaries. Variation is apparent among the water users regarding several socio-economic and demographic characteristics. The logit model is used to analyze the relationship between dichotomous relations of satisfaction level (satisfied/dissatisfied) with the irrigation system by the help of certain independent variables. The result shows that the variables such as water availability on time, location of farm, land size, education in terms of schooling years and rice productivity significantly influenced the satisfaction of the system beneficiaries in the study area. It is further suggested that water distribution system should be upgraded in view of the water availability, farm location and size of the farm to improve users' satisfaction for the effective management of FMIS in the long run.

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Soils of rainfed rice fields have unique characteristics. Inland valleys are extensively found in West African savannas, and their hydromorphic valley bottoms are intensively used for rainfed rice-culture during rainy seasons when become wetlands. Data of rainfall and soil moisture are perennially collected in a study site located in Northern Region of Ghana. The soil of the site is classified as Dystric Planosols. The soil moisture retention curve at a depth of the soil is identified from observed volumetric water content and matric head. Since the soil is variably saturated, it is important to clarify abruptly changing hydraulic properties of the soil near saturation. A bimodal model including eight empirical parameters turns out to be suitable for this purpose. The vertically one-dimensional Richards equation is considered to reproduce infiltration process of rainwater into the soil. The saturated water content, one of the empirical parameters, and saturated hydraulic conductivity are assumed to be functions of the depth of soil. Then, the finite element method is applied for solving the Richards equation to simulate the process. The simulation results are in good accordance with actually observed data. The physically-based model serves as a tool for comprehending formulation process of the wetlands at early stages of rainy seasons.

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This paper presents advective and dispersive solute transport processes in naturally heterogeneous porous formations based on a random walk particle tracking method. Specifically, the disparity of macrodispersivities estimated from temporal moments of breakthrough curves at control planes and from spatial moments of particle cloud is investigated in non-uniform flow systems under the three different conditions of hydraulic conductivity distributions. For both temporal and spatial moment approaches, longitudinal macrodispersivity estimates in stratum porous formations are in considerable agreement with the results reported in the literature. The disparity of macrodispersivity attributes to the nature of both approaches to evaluate a travel distance of particle plume. While the second central temporal moments in stratum aquifer asymptotically approach a constant value regardless of the injection and pumping rates at active wells, the behavior of the second spatial moments depends upon the porous formations and pumping rates. Furthermore, spatial moment approach represents a potentially valuable tool in the assessment of transverse macrodispersion process in heterogeneous porous media.

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An experiment was conducted in a vinyl house at Gifu University, Japan, from June to November 2007 to elucidate the water stress effects on Soil Plant Analytical Development (SPAD) chlorophyll meter reading (SCMR) and its relationship to nitrogen status and grain yield of soybean under the three soil types. The first factor was the three soil types, comprising clay loam, sandy clay loam, and sandy loam, classified as Inceptisol, Ultisol, and Andisol, respectively. Water deficit (D) was the second factor with four levels including D_1(0-25%), D_2(25-50%), D_3(50-75%) and D_4(75-100%) of total available water (TAW). The soybean grain yield showed linear relationships with ET and LAI among the three soil types. On the other hand, soybean grain yield correlated with SCMR, leaf N and grain N status with significant differences among the three soil types in response to different water deficit levels. The highest soybean grain yield was in Inceptisol, followed by Ultisol, and Andisol in response to the same water deficit levels. The results of SCMR suggest that, seed formation stage is the best time for prediction of adverse water stress effects on nitrogen assimilation in potential yielding ability of soybean.

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An experiment was conducted in a vinyl house at Gifu University, Japan, from June to November 2008 to investigate the effects of water stress on root/shoot ratio and water use efficiency (WUE) at different growth stages, and its influence on yield efficiency (YE) of soybean. The treatment imposed was deficit irrigation with five levels including D_1(0-20%), D_2(20-40%), D_3(40-60%), D_4(60-80%), and D_5(80-100%) water deficits of total available water. Soybean seed yield (Y) significantly correlated to the crop water requirement (CWR) as well as to the leaf area index (LAI) and total dry biomass (TDB) in response to water deficit levels. These relationships indicated the water stress decreased CWR which in turn caused the decrease in LAI and TDB and a subsequent decrease in grain yield. However, WUE and YE values increased with increasing root/shoot ratio up to the D_4 treatment and thereafter, decreased up to the D_5 treatment in response to increasing water deficit levels. The study showed that the most effective economic water usage with the highest YE was at D_4 water deficit. It could produce 21% lower yield per plant, but could conserve 18% irrigated water to produce the same yield compared to the potential yield produced under full irrigation (D_1).

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Understanding stream flow and sediment runoff is essential in trying to maintain rivers and streams. In this study, the authors explored the possibility of above-surface morphologies of vegetation as indicators for comprehensively understanding stream flow and sediment runoff by using a simple method. In order to determine such indicator plants along with their characteristic features as indicators, we conducted classifications of plant species in riparian zone and bar islands and recorded changes of their above-surface morphologies. Meanwhile, we monitored re-growth of cutoff main branches. As a result, we selected willow (salix) as an indicator plant, and height, whether or not there is replacement of main branch as indicative vegetation features. We then examined any traces on the indicative features left by stream flow and sediment runoff. Although there are advantages and disadvantages, by examining the traces, we can utilize these morphological features as vegetation indicators for understanding patterns of stream flow and sediment runoff.

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A peak runoff into an agricultural drainage channel around outskirts of cities often becomes larger and keener according with urbanization of its catchment. Then, the channel would be improved to convey increased runoff water smoothly downstream. It is, however, difficult to enlarge its cross-section and/or raise its embankment, because residential area spreads close to it in such a case. The only way left to this situation is to apply concrete lining so as to make the velocity faster. Additionally, eco-friendly works like fish pools and fish habitat blocks are required and also actually introduced with such improvement works in order not to damage the ecosystem in it. However, even if fish pools are introduced, they are located every several hundreds meters discretely in the channel. While the flow in the fish pools is calm enough for fishes to stay and live in, the velocity of flow in every reach between the pools might be too large to migrate through it. In this research migration of two kinds of small fishes, i.e., Pseudorasbora parve and Squalidus chankaensis sp. in the Ooe agricultural drainage channel that has been under improvement are investigated using fluorescent ink and RAPD markers. The following results are obtained; 1) Velocity in improved reaches is too large for small fishes to migrate, especially migrate upstream; 2) Migration is often taken during non-irrigation period. It might mean decrease of the discharge due to a kind of water management is an important and indispensable factor of the ecosystem dynamics; 3) There are several genetic types of Pseudorasbora parve in a single channel and the distribution of the types are dominated by hydraulic conditions.

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A fishway is a kind of facilities attached to a river-crossing structure to aid fishes to ascend it. The entrance of conventional pool-type fishway or fishslope is, however, located apart downstream from the facility, which often let fishes lose the entrance. A fan-shaped fishway and a terrace type fishway that is a modified form of the fan-shaped one are improved versions of pool-type fishway and fishslope whose entrances are widely opened in order for fishes to find them safely and surely. The effectiveness of their widely-opened entrance is known qualitatively by several surveys, whereas not known quantitatively. The aim of this paper is to confirm its superiority over the conventional ones by investigating the ascending routes of juvenile Ayu (Plecoglossus altivelis) at two terrace type fishways. The path of each fishway is spatially devided by sand bags into three routes, i.e. right side, center and left side and the number of ascending fish is counted by using video-cameras installed at the upper end of each route. As a result, 66.6% of acsended fish entered the fishways from sides. They might have lost the entrance, if the entrance were the conventional shape. The choice of route seemed to depend on location of the thalweg or gut. Ayus ascended only in daytime from noon to around 6p.m. in both fishways, which might be due to water temperature, light intensity and their periodic habit. More than 1,000 Ayus ascending the fishways were seen in each day during the investigation period, which would indicate that these terrace type fishways works properly.

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In this paper, 30-years change of rainfall pattern in Miyazaki prefecture was analyzed with the spatial variability, using daily precipitation data from ten-AMeDAS weather stations. A clear increasing trend was found in annual precipitation. While the total amount of rainfall is increasing, number of rainy days has been signiicantly decreasing. This result supports some results of previous studies for long-term precipitation trends in other regions. In terms of seasonal trend, precipitation has obviously increased in fall, and has significantly decreased in spring. Summer precipitation has increased all but northern part of Miyazaki. Number of storm has decreased in spring and summer remarkably, while it has increased in other seasons. From agricultural aspect, much water is needed in this area in spring for paddy-rice planting, and therefore, the decrement trend of precipitation during the period may cause a shortage of irrigation water in the area.

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A field test was conducted on the stability of a pressure-reducing system equipped with two automatic control valves installed in series in a test pipeline in Ohno Mountain of Kagoshima Prefecture. The effects of automatic control valves on pressure reduction in pipeline were investigated via experiment. In the experiment, conventional and/or new type automatic control valves were installed in the pipeline, singly or in series, with safety valves. The result indicated: (1) conventional control valve does not have enough ability to cut the secondary pressure occurs when no flow of water, (2) on the other hand, new type valve can satisfactory cut the secondary pressure, and multi-level pressure reduction by series installation of the valves is possible, (3) applying safety valve in downstream side of control valves is effective to avoid transmitting water hammer pressure having fast propagation speed, (4) it is necessary to have a safety valve fitted on the upstream side of the new type valve, as the new type valve closes quickly and thus pressure increase on the upstream side of the control valve upon valve closure, (5) when the control valves are installed in series, applying the safety valves in both upstream and downstream sides of each control valve (i.e. install in total four safety valves) can control pressure in between the control valves and thus increases safety of the system.

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