[Japan Water Agency] Drainage Survey of Kagawa Canal will be made Seven Years after the Last Survey

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Drainage Survey of Kagawa Canal will be made Seven Years after the Last Survey4 October, 2017

Japan Water Agency (=JWA) is going to implement the drainage survey,draining all the water out of the downstream section for about 8km from Doki River siphon area of Kagawa Canal's main channel and then conducting the function survey of the facility from October 11, 2017. The details are explained below. This time the site tour will be planned for the press on October 14 from 13:30 and we all welcome their coverage of this implementation.

In the past, the drainage survey was made in Asan Tunnel of Kagawa Canal in November 2010, first time in 36 years after the start of water conveyance and similar function survey was conducted to check the deterioration status of the canal. At that time the covered section was upper reaches of the main canal, i.e. upstream of Hozan Reservoir. The similar survey was again made from the said Hozan Reservoir down to the inside of Kotohira Town in October 2011. Accordingly this year the different section will be covered.

Importance of Kagawa Canal

Because of the geological location of Kagawa Prefecture facing north of the Shikoku Mountains, it had experienced a number of draughts in summer. Along with the regional development, water supply (for agricultural, industrial and domesitic use) to this region had become crucial and become the biggest desire of the people there.

Kagawa Canal in brief

Kagawa Canal construction was planned as a part of the Yoshino River Comprehensive Development project and its construction started in 1968. It completed in 1975. Since the start of water conveyance in 1974, it has kept supplying domesitc, irrigational, and industrial use water to almost all the regions of Kagawa Prefecture, i.e. to cover 8 cities and 6 towns. This has become the biggest lifeline of Kagawa Prefecture.

The dails of the Survey

Outline	1) Kagawa Canal has been serving water for agriculture, domestic and industrial use throughout entire Kagawa Prefecture for 43 years since it started operations in 1950.
	2) For the purpose of supplying water for long in the future, it is necessary to check and precisely determine the current deterioration status of the canal and then to study the preservation measures for the future, taking necessary treatments based on the survey result.
	3) As mentioned above, in November 2010, we drained the Asan Tunnel, which was used for the water conveyance of Yoshino River to Kagawa Prefecture and conducted the survey of the upstream section of the main canal. And its findings were that the facility condition was much better than anticipated and found no spots which urgently needed the countermeasures.
	4) The survey of this time is to focus on the survey from inside of the canal in the tunnel and siphon (the waterway crossing beneath the river and road) after draining the water out of the way. As for the downstream section, we have had the survey in November 1992, November 1993, October 1999, October 2003, and October 2011. So this time, we are planning to implement the survey for the sections which have not been surveyed yet or the sections where the repair works were done right after the above surveys.
Period of the survey	For a total of ten days from October 11, 2017 through October 20, 2017. (This period will include the days test and operational check will be made for re-opening.)
Target Section	About 8km from the siphon of Doki River (located in Manno Town, Kagawa Pref.) downward
Type of survey	*appearance survey of the concrete surface Check if there are cracks, floating areas, peel-off, deformation, rock pockets, leakages, construction joints, etc.
Type of survey	*Health condition survey of concrete Neutralization, strength test of concrete, possible cavities behind the rear surfaces of the tunnel

Alternative water sources

During ten days of the above survey, two water purification plants will be affected, i.e. the suspension of water supply from the canal. To avoid such suspension leading to the stoppage of water supply service, water is to be supplied from the alternative water sources, as follows:

(Domestic water) Tobu Water Purification Plant: from Naiba Dam
(Domestic water) Ayakawa Water Purification Plant from Fuchu Dam

Other plants and industrial water and irrigational water supply will not be affected.

Open day of the survey for the press

Inside of the siphon of Doki River will be open for the press, as follows:

Date	October 14, 2017 from 13:30- (Reception to start:13:00)
Gathering place	Kagawa Canal Operation and Maintenance Office
The area to be open for the press	Inside of siphon of Doki River
Application	Those who request for the participation should submit the application by 17:00 of October 12, 2017 to the attention of the said office.