|In order to solve the problem of Isahaya Bay:
Decision on four issues and execution of seven items
Concerning the issue of Isahaya Marsh, there have been lively discussions in
Japan, prompting us to choose either land development or protection of natural
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.
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
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:
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
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.
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
Social responsibilities to be borne by such authorities concerning
reclaimed land utilization must be by far heavier than any other type of land
Marsh: A Vast Wildlife
We may take Bayern State of Germany
as an example of a land improvement project with putting emphasis on preserving
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.
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
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."
reputation of the double reclamation-by-drainage method of Holland gradually
Fading the "Myth of the double
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
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.
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
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.
place is also a registered marsh with the Ramsar Convention, and is being
considered one of the most important bases to constitute the European
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
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
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
4) To separate marsh zone and estuary/water-route
With this determination, in concrete terms we need to carry out the
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
Second, following reducing the area of farm land to be created, the
front bank should be considerably set back towards inland.
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.
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.
existing bank should be raised to the prescribed level.
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
These are the main points to be implemented.
As a model of reclaimed lands in the twenty-first century
Other remaining problems are as
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.
the water gate of Oosterschelde, "Barcon-project ( = barrier control project)"
started in 1977 with an aim of environmental improvement through fine control of
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
Next remaining issues are measures against injury from
salt and against land subsidence caused by relying on underground water for
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.
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.)