East-Mikawa area is located in the east part of Aichi prefecture. This area faces the Pacific Ocean and the Mikawa bay and it extends to the Toyogawa valley. This area possesses a large area traffic system such as the Tomei expressway, Tokaido Shinkansen, and Mikawa port. The area is composed of 4 cities and 11 towns or villages. At Toyohashi City and the Atsumi peninsula, there is the high-value added production system. The production system strongly depends on Toyogawa water. In this area, there are some policy issues: the water demand and supply in Toyogawa valley, regional differences of aging and depopulation, and environmental preservation in Mikawa bay and Okumikawa region.
We attempt to construct a multi-regional econometric model. It offers a basic tool to analyze policy issues in this area. Our purpose is to develop the model that can be analyzed social and economic situations at each cities, towns, and villages in East-Mikawa area. In this paper, we focus on the economic structures of Toyohashi City, Toyokawa City, and Gamagoori City. These are main cities in East-Mikawa area. We examine the water demand and supply structure of Toyogawa valley.