Reality Cheques - Agri-culture: Reconnecting People, Land and Nature - page 61

productively in order to produce a late winter or early spring crop of grass.
More importantly, when the river did flood, water was stored on the
meadows and did not harm housing or other vulnerable areas. However,
in the intensification of food production, most of these meadows were
converted to arable fields. At the same time, rivers were tamed through
channelling, field sizes increased, hedgerows removed, and houses built
on vulnerable land. Now, when it rains, the consequence is increased
flooding to vulnerable areas. It looks as though there has been 'too much'
rain; but, in truth, this is largely due to changes in the landscape.
In Germany, Rienk van der Ploeg and colleagues have correlated loss
of meadows with an increased incidence of inland floods. Over a century,
6 of the 12 most extreme events have occurred since 1983. They show
that changes in the diversity of the use of agricultural land are the main
cause of flooding. In particular, permanent meadows have been converted
to arable fields, some 1.5 million hectares since the mid 1960s. Surface
sealing and compaction means these fields are less likely to hold water
during winter. Another 4.5 million hectares of wetland soils have been
drained since the 1940s. Thus, when it rains, water contributes more
rapidly to river water discharge, thereby increasing the likelihood of
flooding. The cost of two floods in 1993 and 1995 was nearly 2 billion
Deutschmarks, and van der Ploeg concludes that the conversion of arable
back to permanent meadows would be economically and environmentally
beneficial: 'It must be acknowledged that any further increase in agricultural productivity
is likely to cause additional adverse environmental effects. Future farm policy must pay
more attention to the environment'. 23
Japan provides another example of the wider value of agricultural
wetlands - in this case, irrigated paddy rice fields. Japan's very high rainfall
is concentrated into a few months within a landscape characterized by a
high mountain chain. With a very short flow time to the sea, this means
that much of the country is subject to severe flood risk. Paddy rice
farming, though, provides an important sink for this water. There are more
than 2 million hectares of paddy rice in Japan, and each of these hectares
holds about 1000 tonnes of water each year. In the Koshigaya City basin,
25 kilometres north of Tokyo, paddy fields close to the city have been
steadily converted to residential uses over the past quarter century. But
as the area of paddy has declined by about 1000 hectares since the mid
1970s, so the incidence of flooding has increased. Each year, 1000 to
3000 houses are flooded. In whole watersheds , woods and farms on steep
slopes have been identified as having the greatest value in buffering and
slowing water flow, and minimizing landslides. Diversity, though, is
critical. As Yoshitake Kato and colleagues have put it: