Irrigation Systems in Japan

Abstract

This paper portrays the distribution pattern of irrigation systems in Japan and then analyzes the pattern with respect to elements of the natural environment and of the irrigation development process. Irrigation systems in Japan are classified into (1) river, (2) pond, (3) lake, (4) groundwater, (5) torrent, and (6) other systems. River irrigation systems dominate overwhelmingly and occur widely, but especially in eastern Japan. Pond irrigation systems are important in western Japan, centered on the Inland Sea. Various types of irrigation systems exist together in the Kanto district, and torrent systems are common in mountainous areas. The basic features of irrigation systems in western Japan were formed during the Kofun and Nara periods (300 to 800 A.D.). On the other hand, the main systems in the east were built largely in the Sengoku and Edo periods (1450 to 1867 A. D.). In the large systems, a hierarchical structure of water management cooperatives and water delivery methods that accords with the branchlike network of canals was established in the Edo period (1600 to 1867 AD.).