Impacts of below-ground structures on the groundwater environment and their management

Japan consists of four main islands (Hokkaido, Honshu, Shikoku, and Kyushu) and around 6,800 smaller islands of varying size. The country (of 380,000 square kilometers in area) stretches over some 3,200 kilometers from northeast to southwest in the Pacific Ocean. The geography of Japan comprises 80% mountainous area, 70% of which is forest, and less than 20% habitable area. Most of Japan’s major cities (e.g. Tokyo, Yokohama, Nagoya, Kyoto, Osaka, Kobe, Fukuoka, Sapporo, and Sendai) have been developed on alluvial and diluvial plains (Figure 1).