VOL.6

Vol.6

Agricultural Water: the Past and the Future

Agriculture has long been a major user of land and water in Japan. Water, generated by rainfalls in the mountainous regions of the country, flows towards the plains, carrying with it the highly nutritious mould derived from the fallen leaves of deciduous trees. It is then led through irrigation channels to the surrounding rice paddy fields.

Two thirds of Japan's land surface is mountainous. However, her plains are tiny by comparison with those to be found in continental countries. If the rain were not to be controlled, it would flow like a waterfall into the sea. Moreover, most of the cultivatable land in Japan is found in the alluvial flood plains of the country's large rivers.

The large-scale development of paddy fields in these plains began during the Edo Period (1603-1867), when the governing Tokogawa Shogunate assumed control of large river basins and proceeded to develop sophisticated methods of flood control and of irrigation.

Large rivers were diverted away from populated areas; and new irrigation and drainage canals were excavated in order to distribute supplies of water to every corner of plains all over Japan.

The Saitama plain is a major part of one of Japan's largest, the Kanto plain. The latter, which today also includes Metropolitan Tokyo, has a very gentle gradient of about 1/5000. In rice cultivation, 40% of the water supplied is absorbed by the plants and the remaining 60% is drained off. Here, water drained from the paddy fields is stored in weirs and reservoirs and re-used many times.

The construction of a water recycling system, in which water from mountain areas was directed back and forth between rivers and paddy fields and eventually into the sea, was completed thanks to many years of effort and much accumulated experience. The system was maintained not only by the engineers assigned to the task by the Shogunate, but also by the farmers who were using the water.

They fought side by side against flood and drought and worked together to maintain the canals by dredging them and removing the accumulated algae. They also fought each other over the sharing of water supplies. The rules covering the use of water have been set out and maintained by farmers in every community.

For many generations, agricultural communities have had to overcome numerous difficulties in order to ensure adequate supplies of water. These supplies have contributed to the preservation of the environment by helping to produce food, by watering plants and trees and by cleansing the rivers. The agricultural water network not only keeps the earth moist but also feeds the irrigation channels and paddy fields as well as keeping groundwater at the required level. In addition, it prevents earth subsidence and replenishes underground watercourses.

The nutrients collected in the forests and transferred to rivers have vitalized the soil in the paddy fields, thus preventing the problems that could be caused by repeated cultivation. This has made it possible to sustain rice crops for over 2000 years.

The water infrastructure, including the irrigation systems, that has been developed in plains all over Japan during the past 2000 years has become part of the country's natural surroundings and continues to support the lives of its people. One might ask whether there is any other country which has developed its land resources through the efficient use of water as effectively as Japan.

The Tone River, whose headwaters are in the mountains of Saitama, was diverted from its original course in order to prevent flood damage in the populated areas of the Prefecture. Consequently, water supplies do not come directly from the river, but from the agricultural water that the river provides. Any loss of agricultural water in Saitama therefore results in losses to the area's overall water supply.

Since the period of high economic growth between 1953 and 1971, quantities of agricultural water have been used to meet the increased demand for water in the urbanized regions. It is our fervent wish to ensure that our remaining agricultural water is conserved for future generations.

World Water Assessment Programme

The establishment of the UN-wide World Water Assessment Programme (WWAP) was announced in 2000 by Koichiro Matsuura, Director-General of UNESCO, and the publication of the World Water Development Report (WWDR) was supported by the Ministerial Conference during the Second World Water Forum, which took place in The Hague in the same year.

The WWAP is one of the most important challenges in Natural Sciences, one of the five components of UNESCO. Mr. Matsuura asked the Japanese Government to assist in the establishment of the WWAP, and the former has co-operated from the outset, providing financial assistance, assigning experts to the WWAP Secretariat and conducting case studies.

The WWAP Secretariat of WWAP is currently housed in the Paris headquarters of UNESCO. It has received formal proposals for co-operation, including financial assistance, from twenty-four UN organizations and 77 world governments. Over 100 countries have expressed their intention to participate in the Programme.

"The WWDR is organized in six main sections: a background, an evaluation of the world's water resources, an examination of the needs for, the uses of and the demands on water ('Challenges to Life and Well-Being'), a scrutiny of water management ('Management Challenges'), seven representative case studies highlighting different water scenarios, conclusions and annexes".

It is stated in the 'Background' section that, "At the beginning of the twenty-first century, the Earth is facing a serious water crisis, and all the signs suggest that it is getting worse and will continue to do so, unless corrective action is taken. This crisis is one of water governance, essentially caused by the ways in which we mismanage water. But the real tragedy is the effect it has on the everyday lives of poor people, and the crisis is experienced also by the natural environment."

"We know most (but not all) of what the problems are and a good deal about where they are. We have knowledge and expertise to begin to tackle them. We have developed excellent concepts, such as equity and sustainability. Yet inertia at leadership level, and a world population not fully aware of the scale of the problem (and in many cases not sufficiently empowered to do much about it) means we fail to take the needed timely corrective actions and put the concepts to work."

The WWDR requires decision-makers, as well as people who are able to understand the problem of water crisis and to take actions to solve it.

"Eleven challenge areas adopted in the WWDR cover health, food, environment, shared water resources, cities, industry, energy, risk management, knowledge, valuing water and governance, four of which have been discussed in the World Water Forum. The WWDR was compiled with the following principles." "A key component of the WWAP is the development of a set of indicators for the water sector. These indicators must present the complex phenomena of the water sector in a meaningful and understandable way, to decision-makers as well as to the public. They must establish benchmarks to help analyze changes in the sector in space and time in such a way as to help decision-makers to understand the importance of water issues, and involve them in promoting effective water governance." Moreover, it is the world's poor who are affected most directly and most seriously by the worldwide water crisis. For this reason, the WWAP should concentrate its attention upon the developing countries, to which the developed countries should provide relief.

The publication of the WWDR was announced in the World Water Forum, which took place in Japan in 2003. The success of the Forum has made it widely known that Japan is proficient in the risk management of water-related disasters. This has resulted in the establishment of the "UNESCO International Centre for Water Hazard and Risk Management" (provisional title) within the precincts of the Public Works Research Institute in Tsukuba Science City (scheduled to open in March 2006).

Japan has a vital role to play during the 21st. century in the resolution of the world's increasingly serious water-related problems.

Sources:UN/WWAP (United Nations/World Water Assessment Programme). 2003. 1st UN World Water Development Report: Water for People, Water for Life. Paris, New York and Oxford. UNESCO and Berghahn Books.