It is important to analyze the hydraulics of pipeline irrigation system for visualizing the proper pressure distribution. In this paper, the hydraulic transient approach is presented for determining the hydraulic pressure and steady state discharges at nodes and valves. In order to develop a systematic, quick and flexible analytical procedure, an alternative to specified time intervals, namely a staggered grid, is adopted. The equation for the determination of discharges at valves is modified to calculate only steady state conditions at irregular field slope settings. An algorithm is developed which permits flexible running system. The results obtained by this unsteady flow method (UFM) are compared with the results obtained by a back step method (BSM) and the analyzing method is found to be accurate.

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Applicability of the conventional discharge equation for estimating water abstraction by a torrent intake of bar screen type is experimentally investigated. The experiments carried out under a variety of hydraulic and bar screen conditions indicate that depending on length, slope and clearance of the bar, the discharge coefficient defined may take uneven values that are outside of its normal design range of 0.50 to 0.55. This implies that the conventional discharge equation is less versatile in designing a torrent intake. An alternative discharge equation is thus proposed which is expressed in terms of diameter, clearance and modified length of the bar, and its applicability is also experimentally tested. The results show that though use of the equation is limited to the intake with a bar sloping of less than 50°, it gives an appropriately even value of the discharge coefficient, i. e., 0.62, for different configurations of the bar. Experiments also show that in case that a deflector or an upright stoplog are installed in a water cushion to enhance the water abstraction form the intake, value of the coefficient should be taken as 0.68.

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This study is carried out to estimate the buffering capacity and self-purification of Pinus densiflora forests. The quantity and quality of rainwater stemflow and throughfall are analyzed to compare with one another. Since rainwater is a source of stemflow and throughfall, their amounts are strongly influenced by the amount of the rainfall input to forests. So, we try to figure out the quantitative changes of stemflow and throughfall that are presented by the quantitative fluctuation of rainfall, defining the rainfall factor as an independent variable and stemflow and throughfall as the dependent variables. The rainfall factor is divided into two variables ; rainfall amount and intensity for statistic analysis. Referring to the results of stemflow and throughfall, their amounts do not increase at the same rate with the increments of rainfall amount and intensity in an absolute value. We assume that there are some complex interactions between rainfall amount and intensity for producting the stemflow and throughfall. And then multi-regression analysis is made by using two factors as independent variables ; the rainfall amount and intensity. The results are Y1 = 17.58X1 + 609.53X2 -565.68 (R^2 =0.5863), Y2 =104.75X1 + 83.93X2 + 406.97 (R^2=0.5265)(Y1 : Throughfall, Y2 : Stemflow, X1 : Rainfall amount, X2 : Rainfall intensity). In the case of throughfall, both amount and intensity of rainfall are significant and rainfall amount is more correlated with throughfall than rainfall intensity. It is proved that output of stemflow is correlated not with rainfall intensity but with rainfall amount.

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An investigation on water quality and hydrology is conducted in an agricultural watershed (74.2 ha) dominated by rice paddy agriculture, in which a circular irrigation system is implemented and some species of aquatic-plants in the drainage river are removed. The mass balance of pollutants is clarified such as nitrogen, phosphorus and chemical oxygen demand (COD) for three years. In addition, the relationship between the amounts of nutrient contents in the removed aquatic-plants and the mass balance of pollutants is discussed. From results of water quality and hydrological investigation, it is shown that the study watershed processes purification function for phosphorus and COD, partially for nitrogen. The amounts of nutrients in the aquatic-plants are 0.937 kg/ha for total nitrogen (T-N), 0.057 kg/ha for total phosphorus (T-P) and 6.0 kg/ha for T-COD. However, these contributions of the aquatic-plant removal to pollutant reduction are relatively small because of only 1 % land occupation of the aquatic-plants in the watershed.

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Recently we confront the contradiction that in urban areas people suffer from water shortage where rainwater not only cannot be utilized effectively, but also city flooding is caused. One of the solutions to this problem is to make better use of rainwater catchment systems. Such systems are becoming popular and well known as being useful for saving city water and preventing city flooding. The number of such systems is gradually increasing and in most cases large-scale ones are equipped in public buildings such as schools. Obviously, since their effect increases with the total capacity of those equipped, they must come into wide use even in individual houses. The number of local governments developing grant-in-aid programs to promote the diffusion of rainwater catchment systems continues to grow. The Internet is becoming so familiar that we can easily access information on web sites. With such a background, new questionnaire survey methods, termed electron survey methods, are proposed. In this paper, a system for collecting information on the present state of grant-in-aid programs by local governments and to examine its advantages and disadvantages is attempt.

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Experimental laboratory studies were conducted on a fishway of pool type. The fishway consists of three parts. The upstream and the downstream parts of the fishway are built of X-type concrete blocks and form stilling basins for fishes to rest. The middle part of it is built of mountain-type concrete blocks and is designed to guide fishes. The design water depth of the inlet of the fishway is 20cm. The scale of the hydraulic model is 1:27 to proto-type and the law of similitude of Froude is applied to the experiment. Water depth and velocity distributions are measured, and the flow conditions are examined to clarify whether ayu are able to migrate upstream via the fishway or not.

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A major part of the semi-arid area in India has the Vertic Inceptisols soils. These soils are shallow, located on lands exceeding 2% slope, and hence quite prone to the soil erosion. The crop productivity in these soils is affected by less amount of water available to the plants and because of severe loss of the soil during the heavy storms. A runoff simulation model is developed particularly for the Vertic Inceptisol soils, which is relatively simple in concept and requires a reasonable amount of data. The developed model integrates the hydrological processes of evapotranspiration, and soil moisture redistribution and predicts seasonal runoff, soil moisture storage, and deep percolation on a daily basis. In the developed model, the retention parameter is calculated based on the soil moisture accounting procedure, and the deep percolation is estimated on the basis of time delay factor. The model is validated against the measured data from the Vertic Inceptisol fields. The runoff predicted by the model matches well to the observed runoff from the small agricultural watershed.

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The irrigation indicators of three land forms (viz. : flat plots, ridges and camber beds) developed on the Vertisols of the Accra Plains of Ghana are studied using a legume (i. e., cowpea) and a cereal (i. e, maize) as test crops. The water requirements of the test crops are monitored by a combined simultaneous utilization of soil and plant parameters : (1) soil moisture (2) leaf-water potential. Differences in the bulk densities of the three land forms (viz. flat plots (F), ridges R and camber beds (CB)) are 1.41-1.48, 1.39-1.43 and 1.26-1.37 Mg/m^3, respectively, with F having the highest bulk density and CB the least. The soil moisture content of the three land forms measured by Thetaprobe after 24 hours of irrigation follows the sequence of the bulk densities, i. e, F: 26-27, R : 24-28 and CB : 20-28 %(g/g). While test crops show very little differences in leaf-water potential across land forms (i. e, cowpea : F : 6.5, R : 6.3 and CB : 6.5 bars, and maize : F : 5.5, R : 5.8 and CB : 6.0 bars), cowpea appears to be more drought prone than maize. Leaf-water potential has an inverse relationship with soil moisture for both test crops, thus indicating that it could conveniently be used to determine the water status of crops.

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This paper aims at investigating the relationships among the irrigation area, house roof as catchment area and tank volume for the purpose of irrigating the house crops by using the harvested rainwater from house roof. These relationships are derived by water balance simulation of daily ET of Lettuce plants and rainfall in Naha, Okinawa. At first, the tank volumes are determined for lOa catchment area when 20000, 25000, 30000 plants are planted in lOa. Similarly, the tank volumes for the catchment area of 20a and 30a are determined when 20000, 25000, 30000 Lettuce plants are planted in 1 Oa. The required tank volumes for irrigating 20000, 25000, 30000 Lettuce plants established in lOa are 37, 47 and 58m^3, respectively, for the catchment area of lOa. When the catchment area is increased up to 20a, the required tank volume is simulated as 32, 40 and 50m^3 in order to irrigate 20000, 25000 and 30000 Lettuce plants per lOa, respectively. Even, with the increase of catchment area over 20a, the volume is the same as that of the catchment area of 20a.

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Instructions are given to prepare the manuscript of an English paper submitted to the Journal of Rainwater Catchment Systems. Being a model in itself, the document demonstratively prescribes the layout of the manuscript. Manuscripts should be typed on one side of white A4 size paper when they are submitted. Accepted manuscripts will be off-set printed. Titles of papers, names and affiliations of authors, abstracts, main texts, headings, references, equations, mathematical symbols, captions of figures and tables and so on should be in specified fonts. All references cited should be collected together at the end of the paper. Figures and Tables with their captions should be placed appronriately.

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Instructions are given to prepare the manuscript of a Japanese paper submitted to the Journal of Rainwater Catchment Systems. Being a model in itself, the document demonstratively prescribes the layout of the manuscript. Manuscripts should be typed on one side of white A4 size paper when they are submitted. Accepted manuscripts will be off-set printed. Titles of papers, names and affiliations of authors, abstracts, main texts, headings, references, equations, mathematical symbols, captions of figures and tables and so on should be in specified fonts. All references cited should be collected together at the end of the paper. Figures and Tables with their captions should be placed appropriately.

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