Surveys Carried Out on Completion of the Barrage
［The 1994 Survey on the Nagaragawa Estuary Barrage］
The Nagaragawa Estuary Barrage project progressed to construction of the main barrage structure in 1988. By the end of 1993, the gates were fully installed, and construction of the main barrage structure progressed far enough for the barrage to go into operation. As the project entered a new phase, investigations on disaster prevention, the environment and salinity were carried out for a full year in fiscal 1994, while the gates were actually in operation. The main investigation items were:
- Measures to counter water infiltration into ringed lands
- Method of draining ringed land
- Safety against floods, storm surges, earthquakes and seismic waves
- Quality of water and sediment
- Upstream and downstream travel of fish
- Living conditions for animals, plants, fish and shellfish
- Salinity
- Functions of the barrage and related facilities
The survey was open to general participants seeking advice and guidance from the experts on the Committee for the Nagaragawa Estuary Barrage Survey. The results were published as they were obtained. From the commencement of the survey on April 1, 1994, an enormous amount of data was collected and analyzed. Interim results of the survey were published on January 6, 1995, under the title "The Interim Report of Investigations on the Nagaragawa Estuary Barrage."
The results of the full year's investigations were included in the Nagaragawa Estuary Barrage Survey Report (Final Draft) presented at the fifth Investigation Committee meeting (March 30, 1995). The Nagaragawa Estuary Barrage Survey Report itself was published on July 11, 1995.
Outline of the Nagara Estuary Barrage Survey
Survey for measures to counter water infiltration
Local explanation meeting
A survey of Ayu traveling upstream
Feb. 1, 1994
Construction Minister announced a plan for an open survey with guidance from a survey committee consisting of experts, with published survey results.
Mar. 23
First meeting of the Nagaragawa Estuary Barrage Survey Committee
Apr. 1
The survey began.
May 19-21
The survey was carried out with all the gates in operation (the May Survey).
June 13
Second meeting of the Nagaragawa Estuary Barrage Survey Committee
Sept. 18 - Oct. 28
The survey was carried out with all the gates in operation (the September Survey).
Sept. 26
Third meeting of the Nagaragawa Estuary Barrage Survey Committee
Sept. 29
The gates were fully opened temporarily when Typhoon No. 26 approached the area (until Oct. 1).
Dec. 1-24
The survey was carried out with all the gates in operation (the December Survey).
Dec. 12
Fourth meeting of the Nagaragawa Estuary Barrage Survey Committee
Jan. 6, 1995
The Interim Report of the Nagaragawa Estuary Barrage Survey was published.
Feb. 1-15
Feb.: The survey was carried out with all the gates in operation (the February Survey).
Mar. 30
Fifth meeting of the Nagaragawa Estuary Barrage Survey Committee
Mar. 31
The Survey Committee reported the survey results to the Minister of Construction.
July 11
The Nagaragawa Estuary Barrage Survey Report was published.