水利権からみた富山県の農業用水 The Profiles of the Water-right-based Intake of Agricultural Water Involving Six Major Rivers in Toyama
This study aims to establish the profiles of the intake of agricultural water involving six river networks, each consisting of one of the six major rivers in Toyama and some minor streams in its vicinity. Of the three chief uses of water, agricultural, city and industrial water, the first alone is taken in and distributed through open canals and channels. Hence the difficulty of obtaining accurate data on the actual intake of agricultural water from particular rivers. For the present purpose, therefore, instead of seeking to collect data on the actual intake, I have opted to substitute available data on water-right-based intake. By processing and analyzing the data with respect to the fluctuation of intake for each month of the year, I have obtained the following results : (1) The data bear out our intuition that the irrigation period begins in April and ends in September and that the volumes of agricultural water to be taken in by water rights increase in April, peak in May and decrease in September. (2) The fluctuation patterns of intake involving the river networks centering on the Joganji, the Jinzu and the Sho, all of them major rivers in the central part of Toyama, show rates of intake per unit area which are quite similar to the average rates for the whole prefecture, both during the irrigation season and in the rest of the year. The patterns involving the river networks represented by the Kurobe and the Hayatsuki, respectively, both in the eastern part of the prefecture, show intake rates visibly higher than the prefectural average, at least during the irrigation season. By contrast, the pattern involving the river network centered around the Oyabe, in the west of the prefecture, shows intake rates distinctly lower than the prefectural average, both during the irrigation season and in the rest of the year.
富山県立大学紀要 6, 116-128, 1996-03-29