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close this bookFreshwater Resources in Arid Lands (UNU, 1997, 94 p.)
close this folder5: The development of groundwater resources on the Miyakojima Islands
View the document(introduction...)
View the documentIntroduction
View the documentOutline of the Miyakojima Islands
View the documentGeology and the hydrological cycle
View the documentOutline of the irrigation project on Miyakojima
View the documentThe construction and concept of the underground dam
View the documentThe Construction of the Cut-off Walls
View the documentThe construction of the intake facilities
View the documentThe storage situation of the Sunagawa underground dam
View the documentConclusion
View the documentBibliography

Outline of the Miyakojima Islands

The Miyakojima Islands are located about 1,900 km south-west of Tokyo, comprising an area of 159 km². The climate is characteristically subtropical with a high annual average temperature of 23°C and high humidity of 79 per cent. Though annual rainfall is high, approximately 2,200 mm, it is unpredictable and fluctuating because much of it largely relies on rainy-season rainfall and typhoons. Besides this, all the islands are covered by a highly permeable Lyukyu limestone layer that shapes its flat plateau and has resulted in the absence of rivers on the islands.

The islands, with a population of about 48,000, are divided into four administrative areas, Hirara City, Shimoji Town, Gusukube Town and Ueno Village (fig. 1). The main industry on the islands is agriculture and its development strategy is mixed farming, with sugar cane as the main crop and cattle for meat. In recent years, crop diversification has been increased where, for example, vegetables are grown targeting the pre-season of the main island of Japan, and tropical fruits and tobacco are also grown. Furthermore, the now famous All Japan Triathlon Competition is held on Miyakojima every year in April and, since the inception of direct-flight services from Tokyo and Osaka to the islands, tourism has increased steadily.

Figure 1 Location Map of the Miyakojima Islands