VOL.2

Vol.2

The Story of the Arakawa Floodway

Soon after settling in Edo in 1603, Tokugawa Ieyasu, founder and first Shogun of the Tokugawa Shogunate, launched a project to divert the River Tone eastward, away from the Ara River.

The Sumida and Nihon embankments were built to play an important role in preventing the Ara River from overflowing into the Sumida River (then the lower Ara River). Some suburbs of Edo and the southern Saitama in the upper reach of the river were transformed into a vast reservoir. Protected by the two embankments and served by the reservoir, the Edo area benefited from the commercial zones and waterborne transport developed along the Sumida River. Even so, Edo was still vulnerable to frequent floods. The occurrence of heavy rains caused rivers and waterways in lowland areas to overflow nearly every year, and heavy rainfalls in the upper reaches of the Tone River often produced flooding of the upper Ara River, resulting in the invasion of Edo by flows of mud.

Despite limited technology and inadequate funds, the Shogunate's policy was to give preference to the development of waterways, so that the latter could be used to transport the annual tributes (often in the form of rice or barley) to Edo. The safety of the population was a secondary consideration.

After the Meiji Restoration of 1868, the reservoir to the north of the Nihon Embankment was reclaimed. The lower reaches of the Ara River (Sumida River) accommodated many modern factories built to utilize the waterway network by the middle of the Meiji Period (-1910) and thus supported the development of modern Japanese industry. Unlike agricultural land, however, these industrialized and urbanized areas could not withstand flooding. A comprehensive flood-control system was vital to modern Japanese cities, most of which were built in lowland areas or along the lower reaches of the rivers.

After many twists and turns, the River Law was introduced. This placed large rivers directly under the control of the government. The methodology of river improvement was changed, so that floods were prevented by the construction of high embankments. Since then, the term "river improvement" has referred to the construction of flood control facilities.

However, because of severe financial constraints, river improvement under direct government jurisdiction did not progress, except in respect of a few large rivers. In the Ara River basin, including the Saitama area contained within the vast reservoir on the upper reaches, there was an ever-increasing demand for flood control work. In August 1910, a huge typhoon caused the largest flood of the Meiji Period. It led to the loss of enormous numbers of the properties that had been built since the Meiji Restoration; and this, in turn, caused the prices of consumer products to rocket. The government had no choice but to assign the same priority to river improvement projects as it did to its financial policies.

In October 1910, the government established a River Improvement Committee and formulated the "First River Improvement Plan", under which 65 rivers were selected to be the subjects of flood control projects under direct government jurisdiction. Of these, twenty were chosen for improvement during the first phase, including the Ara River, which had important associations with metropolitan Tokyo. The main objectives of the Ara River improvement work, which began in 1911, included the construction of floodways to prevent flooding of the Sumida, to protect Tokyo from flooding and to improve water transport facilities.

The designed flood discharge rate at Iwabuchi, a reference point on the Ara River, was set at 4170 m3/second, which was discharged into the floodways and the Sumida River. The Ara River Improvement project was completed in 1930, with the full opening of the floodways in 1924.

In September 1922, the Kanto area was attacked by typhoon Catherine. Large areas of the Tokyo and Saitama Prefectures were inundated, although the damage was limited to the Eastern side of the Ara River floodway. The Ara River floodway protected the Tokyo area from floodwaters of the Tone River. The area around the Sumida River is now subject to comparatively little flood damage. There are now high-rise building areas in both the upper and the middle reaches of the Ara River. In addition to enhancing the level of safety from flooding, river improvement brings other benefits, such as enlarged inhabitable areas with the development of their infrastructures, thus vitalizing the urban economy.

However, our struggles with rivers continue. Although safety levels are higher, the development of lowland industrial areas has contaminated river water and has led to subsidence, producing the area below sea level. The progressively increasing height of the embankment leads to a greater risk from flooding.

To deal with this risk, "super levee" (high-standard embankment) projects are now in course of completion at the mouths of the Sumida and Ara rivers. A "super-levee" is a river embankment whose width is approximately 30 times greater than that of an ordinary embankment, and it will not be destroyed even by severe flooding. Moreover, the top of the levee provides people living in downtown areas with a valuable urban space, with water and greenery, where they can enjoy natural surroundings. The lower reaches of the Ara River now provide a precious area of water and greenery.

The Daily Record of Paddy Field D

The cultivation of this year's rice crop started with 16 members. The seedlings planted on May 25 had developed well. However, root decay caused by a lack of oxygen forced us to drain the field 15 days earlier than the previous year. Fertilizer was applied 12 days earlier, on July 14, in the hope that oxygen would be introduced while draining. The field was allowed to dry for a couple of days after fertilization, and was then irrigated on July 17. From August 12, there were alternating 3-day irrigation and 4-day drying-out periods. The water was then drained completely on September 7, in preparation for harvesting. All these procedures reminded me of the important role that water plays in rice-growing.

On August 2, the plants sprouted ears with small white flowers on their tips. The sweet juice of the flowers attracts sparrows, against which we have to fight until the end of August. We found that the beating of drums in the early morning and evening was the most effective method of preventing the sparrows from causing damage.

Harvesting day finally arrived on September 22. The combine harvester progressed cheerfully, separating the grains from the stems and depositing the former into hemp bags and the latter on to the field. The grains were placed in a dryer overnight and removed. The harvest this year measured 489.5 kilogram per tan (1,000m2). We encountered more problems this year, but the yield was better than last year's 453.5 kg/tan.

I am often asked what is the most interesting thing about rice growing. Relaxing through contact with the soil, water, green rice plants, sunshine and wind is of course an important element. But nothing can replace the pleasure of harvesting. I picked every ear of rice and never left even one on the field. I surprised myself by behaving in this way.