In order to solve the problem of Isahaya Bay: Decision on four issues and execution of seven items

Marsh Concerning the issue of Isahaya Marsh, there have been lively discussions in Japan, prompting us to choose either land development or protection of natural environment.
Today, more than six months after closing of the drainage gate of Isahaya Bay and when most of the biosphere has stopped functioning, it is time for us to start an argument on the issue from a new view point.
The argument should be for integration of the basic standpoints of both sides; that is, a search for, and examination of, an alternative plan that can coordinate three purposes; prevention against disasters, farming, and protection of environment.
Such an approach will, I believe, be in line with the spirit of the Ramsar Convention.
As a precondition to examine an alternative plan, we are required to recognize the following points as common ground:

First, the thing we have to protect is an ecosystem of the marsh and the "purification function" of the marsh, not a species of mudskippers.
In this connection, our future land improvement projects, including land reclamation by drainage, must be carried out with emphasis placed on protection of the ecosystem of the place.
In March 1994, the Ministry of Agriculture, Forestry and Fisheries set up a sub-committee to examine "the future course to promote agricultural/rural infrastructure improvement projects for building up social overhead capital" within the Planning Committee of the Irrigation and Drainage Council.
With Mr. Kazumi Kurokawa as the chairman, this sub-committee held six meetings, and concluded its discussion results in March 1995.
The report of this sub-committee states, "The agricultural/rural infrastructure improvement projects after the Uruguay Round Agreement must be dealt with in a way something like a Copernican change of attitude on our side."
And in order to do that, "We have to treat both natural environment and various systems as an integrated social common capital of our society, and farmers or rural communities must play a role of the manager of this social capital."
The first element, we have to be well aware of, is that the national government or a prefectural government can implement projects of land reclamation by drainage with its own initiative, without making any "request," because no qualified persons exist under Article Three of the Land Improvement Act.
Furthermore, the decision of project does not require consent of the persons qualified under Article three, and the project plan need not be publicly notified or open for public inspection. The persons concerned can only raise an administrative suit against the project based on the provisions of the Administrative Appeals Law or of the Administrative Litigation Law.
In this sense, our legal system leaves management of the vast social overhead capital, which is reclaimed land, completely to the hands of the authorities who take care of the project.
Social responsibilities to be borne by such authorities concerning reclaimed land utilization must be by far heavier than any other type of land improvement project.

Marsh: A Vast Wildlife Habitat

bird We may take Bayern State of Germany as an example of a land improvement project with putting emphasis on preserving wildlife habitats.
A Participants Union within this State, corresponding to each of our Land Improvement District, maps, within its responsible territory, all important areas and structures for protection of nature or conservation of landscape, Such a Union lays down an individual plan for each land utilization if it includes an ecosystem to be protected.
Thus they try to reduce the impact of the land improvement plan on ecosystems by implementing a transfer or removal, exchange of land, limitation of land utilization, move of farms to be improved through a grouping method, and adoption of extensive agriculture; they carry out all these means based on ecological studies.
Learning from these examples, the Ministry of Agriculture, Forestry, and Fisheries in Japan started setting up biotopes near the land to be improved for agriculture.
It is difficult for us to understand why the same Ministry is destroying valuable marshes, a vast biotope, at the same time.
If they recognize that the marshes are very important wildlife habitats, they should give the same attention for environment to conserve them.

Second, we must well aware of the importance of the fact that the project of turning salt water into fresh water will result in a wide range and long-term environmental disruption.
The double reclamation-by-drainage method in Japan started when we imported the method directly from Holland.
Mr. A. Holker, the chief engineer of Zuiderzee Land Reclamation Office, visited Japan from January to March 1954 with Professor Yansen of Delft Engineering University, to make an inspection of land reclamation by drainage project in Japan.
He said at that time, "The delta project has dual safety; safety of a newly closed levee and that of the existing levee.
It will also create a pool of fresh water, and I think these features are very important for our community."
His word was accepted at that time to praise the merit of double reclamation-by-drainage method as "killing three birds with one stone" by "creating farm land, generating reservoir for irrigation, and protecting the community against disaster."
Later, however, reputation of the double reclamation-by-drainage method of Holland gradually faded away.

Fading the "Myth of the double reclamation-by-drainage method"

a water mill Expansion of cracks of the old bank of Oosterschelde caused by a heavy flood in 1953 was made an occasion for a proposal to close the Oosterschelde bank, and in 1967, the first working harbor was constructed to close the bank.
At that time, environmental groups started pointing out ecological disruption within the bay by turning salt water into fresh water.
Seven years after, in 1974, a Clausewitz committee concluded to build an open-gate style dam which would enable salt water to pass through the gate.
This conclusion, which was quite the proper course to take when we look back after the event, was called a Clausewitz's egg named after a historical act of Columbus who made an achievement that seemed impossible until it had been actually tried and easily accomplished.
We may say that at that very moment the first step of collapse of the myth of the double land reclamation-by-drainage was initiated.
This change of direction extended to, not only fresh-water pond, but to a recovery of the environment of tideless salt-water lakes.
Lake Gravelingen, which was created from 1964 to 1971, is a closed and tideless salt-water lake. Ecological environment so deteriorated after the closing that Hollanders made a water-gate at the place of Brouwers Dam in 1978.
While flowing in fresh sea-water, recovery of the ecological system of the lake was achieved.
Around the same time, they started an environmental utilization of already reclaimed lands.
Ostvaadersplassen, a reclaimed land with an area of 5,600 hectare reclaimed from Ijssel Sea in 1968 was designated as a Nature Conservation District in 1983.
In this place, people are trying to improve the natural environment, making the place a habitat of wild geese, herons, rabbits and other animals by controlling growth of reeds through the adjustment of the water level.
The place is also a registered marsh with the Ramsar Convention, and is being considered one of the most important bases to constitute the European environmental axis.
Thus, in Holland, even reclaimed land by drainage with an original aim at creating farm land, is shifting its purpose of utilization towards environmental improvement.
As it has already been proven that there are so much environmental disruption by turning salt-water into fresh-water, we should not allow now unlimited implementation of double reclamation of land by drainage today.

Proposal for a wise land use

Is it possible to implement utilization of land that can integrate three purposes of prevention against disasters, creation of farming land and protection of environment under the above-mentioned common recognition of basic facts?
I believe that the related parties are now required to decide the following four issues;
1) Not to turn salt water into fresh water,
2) To reduce the reclaimed farm land to the size which can be irrigated by the existing water resources,
3) To keep substantial disaster-protection function inherent in the double reclamation by drainage method, and
4) To separate marsh zone and estuary/water-route zone.

With this determination, in concrete terms we need to carry out the following measures.
First, considering the present situation of irrigation water and the current state of the dry beach line, the area of farm land must be reduced to about one third of the area planned under the current object.
Second, following reducing the area of farm land to be created, the front bank should be considerably set back towards inland.
However, the northern and southern banks must be kept as is planned in order to fulfill its function as the training levee as well as a zone to separate the mouth-river zone and the marsh zone.
Third, because the part of the plan of turning salt-water to fresh-water is to be abandoned, the water gate level need not always be kept 1 meter below water.
We should make more flexible gate-control allowing to blend salt-water.
Furthermore, considering expansion of regulating the pond area due to reduction of farm land area, we will have to take a carefully thought-out measure of control in order to achieve purposes of disaster prevention, natural drainage of hinterland, and recovery of ecosystem/natural environment within the bay.
Fourth, we will be able to carry out regular dredging operations concerning a beach before drainage sluice by separating marsh zone and mouth-river/water channel zone.
Fifth, shape of the front bank should be designed to match with nature of the place, forming a continuous, integrated landscape of farm-land zone and marsh zone.
Sixth, the existing bank should be raised to the prescribed level.
Seventh, following giving up part of the plan to turn salt-water into fresh-water, use of front bank's pumping plants planned in the north, central and south, should be converted to strengthen drainage function for farming lands including existing farms.
These are the main points to be implemented.

As a model of reclaimed lands in the twenty-first century

tulip Other remaining problems are as follows.
The first issue is how to control the water gate for drainage after opening the gate.
We have to give special attention to the fact that environmental conditions within the bank will inevitably degenerate through reduction of an open-mouth area, as well as tidal current and tide range, as long as there is a tide-barrier bank even after the water gate is opened. An example of Oosterschelde of Holland has confirmed this fact.
After opening the water gate of Oosterschelde, "Barcon-project ( = barrier control project)" started in 1977 with an aim of environmental improvement through fine control of the gate.
This project has a wide range of purposes including not only determination of criteria for opening/closing of the gate for disaster prevention, but also risk management measures in case of a tanker's stranding off the bay, recovery of ecosystem within the bay through control of water gate, water level and open-mouth place, and a method of water-gate control to facilitate maintenance/management of the bay for future 200 years. Accumulation of expertise through this project may be of great use for us to manage the Isahaya project.

Next remaining issues are measures against injury from salt and against land subsidence caused by relying on underground water for agricultural irrigation.
As farming land to be created is going to be reduced, utilization of the land created need not stick to production of crops based on land-use type.
We should examine the possibility of development of facility-type farming that can evade the problem of irrigation.
Once the Isahaya project becomes the most advanced base of environmental conservation farming placing emphasis on harmonization of environment and agriculture, it will be in line with a policy of "mitigation" which can make up for a partial disappearance of the marsh.
Furthermore, if we could re-construct the land reclamation project by drainage of Isahaya Bay under the contemporary or enlightened sense of value, we may even expect that this very Isahaya will attract a world-wide attention as a model for a new-type land reclamation project in the twenty-first century.

(This proposal is a little revised version, the original of which was appeared in "Opinion Page" of the Asahi.)



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