Dyes are important tracers to investigate subsurface water movement and solute transport processes. Laboratory tracer experiments with a fluorescent dye, Brilliant Sulfaflavine, are carried out in a two-dimensional water flow tank uniformly packed with glass beads over a wide range of steady state water flow rates. Under ultraviolet (UV) illumination conditions the fluorescent dye emits visible light and is imaged by a digital camera. An imaging processing technique based on UV excited spatial distributions of the fluorescent dye tracer allows to link with a spatial moment approach to identify the longitudinal and transverse microdispersivities. The experimental results show that the mean values of longitudinal and transverse microdispersivities range from 0.095 cm to 0.40 cm and from 0.027 cm to 0.061 cm, respectively. Laboratory study is extended by a random walk particle tracking approach to reconstruct the estimated microdispersivity transitions, demonstrating a good agreement between the experimental and numerical results in homogeneous porous formations of concern. The methodology applied herein represents a potentially valuable tool in the assessment of microdispersion phenomena in porous media.

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An inverse method for identifying the unsaturated hydraulic conductivity in variably saturated seepage flow model is proposed. As the basic equation which governs the forward problem, the mixed-form Richards equation is considered which is conservative in mass balance describing the flow in terms of pressure head and moisture content. For functional representation of the relative hydraulic conductivity (RHC) which is a major unknown parameter to be identified, the free-form parameterized function (or sequential piecewise cubic spline function) which provides high flexibility in identifying the functional form of the parameter is employed. To determine values of the coefficients of the function in the manner that errors between the observed and computed pressure heads are minimized, a simulationoptimization algorithm with the aid of the Levenberg-Marqurdt method is constructed. The method proposed is applied to in-situ soil column in an upland crop field, and its validity is examined in terms of reproducibility of desorption process in the soil. The results show that the simulation-optimization algorithm is successful in finding RHC of functional form, and that the forward solution model with the RHC parameter so identified could well reproduce actual desorption process when air-temperature dependency of the observed pressure head variation is appropriately eliminated.

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This paper examines the applicability and limitations of NDVI-based evapotranspiration estimation method using satellite imagery, applying at arid and semi-arid irrigated agricultural regions for regional water resources management purposes. NDVI-based ET estimation method has been regarded as a low-accuracy estimation method. However, this study shows that the method can estimate ET with high accuracy, by appropriate operation by understanding the characteristics and performance of the method. In a dry land in western United States, NDVI-based method estimated average field ET of the measure crops of the area; alfalfa, bean, sugar beet, corn, potato and wheat, in very high accuracy (3% error), which shows that NDVI-based method has a great potential of contribution on water resources management. However, the method is not good at estimating "daily" ET from "individual" agricultural field, because NDVI cannot evaluate the soil wetness and the simple NDVI-based ET equation is optimized to average field condition of the region. Accuracy of seasonal ET was high (12% error) even for individual agricultural field.

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Pool and weir type fishway is a kind of open channel with slope of constant gradient and connects a drop in a river. When this kind of fishway is built at high dam or debris barrier, it must inevitably be long and large, which induces high cost and long construction period. Recently, spiral fishway that is also a kind of pool and weir type but folded like a spiral has been developed to overcome the difficulties and installed to some high dams. It sometimes fail to dissipate energy and often slant its talwag outward, though it succeeds in cut-down of the cost and period according to some reports. Then, the spiral fishway is improved to be successive "S" shape channel with shallow pools and attached directly on the wall of barrier. At the same time the fishway that consists of several parts made of steel is built in a factory and the parts are assembled on the site, which cut the cost and period remarkably down. In the research its applicability are examined by hydraulic test and fish ascending test in a prototype experimental fishway. Results show that 1) flow is successfully decelerated throughout the fishway and approximately 28% of velocity is reduced at a folding pool, 2) flow at pools is slower than sustained speed of young Ayu (Plecoglossus altivelis) and Amago (Oncorhynchus masou ishikawae) and fastest flow seen at the slit of weir is less than their burst speed, 3) Roughly 90 % of ayu and amago ascend the fishway in 2 days. Consequently, the finshway is exptected to be of help to ascending fish at high dams and debris barriers.

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As the project for the second period, Aichi Water Supply is working to construct a new water channel system by creating multiple upstream water channels and renovating the check gate. Plans to introduce a demand-driven system in the existing downstream channel using a downstream water stage control gate were hindered by the appearance of hydraulic and structural problems such as rise of the water channel and tunnel flooding. Although attention focused on a supply-driven approach, consideration was given to the possibility of introducing a float-type constant upstream and downstream water stage control gate in which a demand-driven water channel system operates as long some extra capacity exists in the water channel upstream from the gate. This type of gate is distinctive in that downstream water level can be regulated using water stored in the water channel upstream from the gate, and offers the advantage of being able to utilize that water without flooding the existing water channel. The operating mechanism of this gate has been shown to possess adequate practical functionality in both on-site testing and performance results from mathematical-model-based simulations. Unlike an open channel system, this type of gate does not require a major investment and allows for limited demand-driven management of the water supply.

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