北陸地方の黒部川扇状地と手取川扇状地と高田平野における1970年代中頃の灌漑水利の地域差を明らかにし，その地域的条件について考察した．黒部川扇状地では統一的・近代的灌漑システムが完成しており，水不足に陥ることもほとんどなかった．手取川扇状地では支線・末端用水路の整備が遅れており，さらに扇状地全域で番水が行われたり，右岸と左岸の用水が対立するなど，黒部川扇状地よりも水利事情がやや悪かった．高田平野では極端な上流優先の水利慣行によって示されるように，3つの中では最も水利事情が悪かった．山間集水面積と被灌漑面積，山間部の標高，扇状地の形態などの自然条件，開発過程や江戸期の領有関係や水利行政などの歴史的条件，農業や兼業などの経済的条件，そして電力事業の進出や行政の動きなどについて考察した結果，黒部川扇状地，手取川扇状地，高田平野の順に灌漑水利を支える条件が良いことがわかった．1970年代後半からの灌漑水利事業の進展により，3つの事例地域の水利事情の格差は小さくなり，いずれの地域でも円滑な水利用が行われるようになった．, It is no wonder that in Japan regional differences and characteristics of paddy regions have often been discussed in terms of irrigation systems, because the irrigation systems have played an important role in supporting successful rice production. This paper describes and analyzes regional variation of irrigation syntems and its background of three alluvial fans of the Hokuriku distict : the Kurobe alluvial fan, the Tedori alluvial fan and the Takada plain. The irrigation systems differed with the alluvial plains in the middle of the 1970s. An unified and modern irrigation system was completed and water shortage problems seldom occurred on the Kurobe alluvial fan. The irrigation system on the Tedori alluvial fan was relatively modernized but rotation irrigation was necessary in the time of drought. Competition was strong between the northern and the southern section of the Tedori alluvial fan. The situation of irrigation on the Tedori alluvial fan was slightly worse than that of the Kurobe alluvial fan. Restrictions on water use were generally severe and elaborate customary water use practices have evolved on the Takada plain. Even during drought season the upstream section could obtain enough water, while the downstream section had difficulties to draw water in ordinary year. In the downstream section irrigation by rotation lasted from May to September every year. The situation of irrigation was the worst on the Takada plain among the three alluvial fans. The present study examines such conditions for irrigation as physical setting, historical background, economic and administrative conditions, construction processes of hydroelectric power plants. Generally speaking, the alluvial fans in the Hokuriku district are favored with various conditions. The existence of rivers with much volume of water, much snow accumulation in the river basins and the topography of alluvial fans are suitable to water supply. Feudal lords at the Edo era encouraged the expansion of rice cultivation based on the construction of sophisticated irrigation systems, and administlation and hydroelectric power companies would utilize water resources by the improvement of irrigation facilities. The variation of irrigation systems of the three alluvial fans caused by the differences in the conditions for irrigation. The Kurobe alluvial fan has the best conditons, while the Takada plain has the worst ones among three. In the long run, however, construction works will compensate for the shortage of the conditions. The national and prefectural projects completed by the middle of 1980s on the Takada plain have greatly improved the situation of irrigation, and many complicated water use practices are disappearing., 論説, ARTICLES