Kansai Airports

Initiatives to prevent rising groundwater resulting from high tides

Airport Island Groundwater Levels - Before Installation of the Water Barrier -

The rising groundwater is related to the structure of the island itself. Kansai International Airport is surrounded by an environmentally friendly rock seawall built with rock material quarried from a mountain. For this reason, the structure is extremely water permeable.

Consequently, when the surrounding sea level rises, the seawater flows into the airport island ground and the groundwater level rises. Likewise, when the sea level drops, the groundwater escapes and the groundwater levels also drop. When measuring the groundwater levels, we found that they rise and fall identically to the rhythm of the rising and falling seawater level.

<Airport island structure (Cross-section)>

<Diagram of the bed below the airport island>

<Ground water levels prior to the construction of the water barriers>

In addition, a problem that has occurred throughout Japan for the past several years, the sea levels around the airport island have risen for unknown reasons through abnormal tides, which occur on more days than normal.

This produces a variety of unusual effects in the airport, such as groundwater seeping from drainage vents in low-lying grassy areas, and water leaking into basement rooms where water prevention is less than adequate.

Rising Groundwater Prevention - Installation of Water Barriers -

Water barriers (underground walls) were built as a radical solution to prevent seawater permeation into the airport island ground, and to curb rising groundwater.

This involved excavating down to a depth of 30 meters, where a non-permeable alluvial clay layer sits. Subsequently, a string of columns made from cement, soil and sand were constructed.

<Diagram of a water barrier>

<Groundwater levels prior to the construction of the water barriers>

<Work underway>

<Work underway>

<Water barrier locations>

Groundwater levels after installation of water barriers

The construction of water barriers around the entire airport island was completed in 2006. This effectively eliminated rising water levels on the island even in the event of abnormal tides and typhoon surges. In fact, this solution eliminated problems affecting airport functions irrespective of sea level increases due to prolonged global warming and long-term ground settlement.

<Groundwater levels after installation of water barriers>

As of 1st April, 2016, Kansai Airports succeeded the operating right for both Kansai International Airport and Osaka International Airport. Please note that the name of the previous operator, New Kansai International Airport Company, Ltd., is described in some materials and articles related to previous operation.