A Historical and Geographical Study on the Process of Development at Isawa-Fan

Abstract

Since the Isawa-fan has so complicated constitution that warping is found in its terrace, the development was made in relation to these topographic zone (chikeiku), and remains of the early Jomon-Age were found almost at the upper part of terrace. After the inhabitants had come to be engaged in cultivation, they moved to the lower part of the Mizusawa terrace gradually. Then the development of Hajiki might have been based on and near “Tsuno-zuka ancient mound” (kofun).The development in cultivation during the Middle Age was made around the Kitakami low-land area and at the Mizusawa terrace, seeing that the premises of Village-lords (gozoku) and familiar names of places in those days are still found there. The remarkable development, east of the warping line, was founded on the construction of the Sanseki, Shigeira and Juan dams, in chronological order, from topographical and engineering viewpoints.The top of the Fan and Uanohara terrace west of the warping line, situated in the upper ground, are thought to be the last in development, except a few partially cleared spots with the Anayama dam and irrigation-ponds. Even at the area where dams are distributed, east of the warping line, the lack of water for irrigation, and trouble about taking water away from other places occurred. Then, after World War II, as a part of “Comprehensive development of the Kitakami River”, composite irrigation and drainage works were introduced; that is: it was planned to use water for effective irrigation, to improve the irrigation of cultivated land of 6, 400ha., and to clear the undeveloped area of 1, 960ha., west of the warping line and Uanohara terrace. Thus, the Isawa-fan was reformed with these new developments.Then recently as the means of solving a contradiction of composite irrigation and drainage works in the area, where members of Anayama-Seki(dam)-Union live, a plan of cultivating the western area at Isawa mura (village) is being carried on by the construction of Hachiya dam.