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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

The storage situation of the Sunagawa underground dam

The groundwater level of the Sunagawa underground dam started to rise immediately after the completion of the cut-off wall in November 1993 and reached the full water level of 31.0 m on 30 September 1995. Since then it has remained at overflowing level, around 31.7 m (fig. 7). We have not seen any partial fluctuation of the groundwater level at upstream or downstream sites along the cutoff wall, either before or after reaching the full water level. Thus, the facts mentioned above verify that the impermeability of the cut-off wall is secured and so also is the permeability of the crest of the wall.