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Despite two decades of efforts to clean up pollution, the River Rhine is
still largely lifeless. The four Rhine nations, Switzerland, Germany, France
and the Netherlands, have spent huge sums on stopping the flow of heavy
metals, raw sewage and poisonous chemicals into the river. But migrating
fish such as salmon have yet to return and the flow of the river itself
has become increasingly unruly.

The limited success of measures to rejuvenate the river is forcing them to
rethink their strategy. They now seem ready to pay more attention to
ecologists who want to return the river to its original state, with
meanders, backwaters, rapids and shallows, flooded forests and pastures –
and free passage for migrating fish. River engineers, chemists and even
shipping companies, are beginning to see the merits of such a strategy.

More vegetation will help cleanse the river of its pollution. Lowering the
dykes to re-create a natural flood plain will help combat floods. Trees,
not imported stone, could once again stabilise river banks. It makes sense
to revive the ‘ecological services’ that the river once provided free of
charge. But how far can this revival go?

Attempts to tame the unruly Rhine began in earnest in the 19th century, with
the ‘rectification’ works of the upper Rhine that were undertaken by the
German engineer Johann Tulla between 1817 and 1876. Until then, the upper
reaches of the river had remained largely undisturbed. For most of its
journey, the Rhine took a meandering path across a wide flood plain of
woods and water meadows.

In the ‘furcation zone’, between Basel and Karlsruhe, the river split into
innumerable branches that continually moved, disappeared and reformed. The
islands between the branches were dominated by flooded forests and wet
pasture. Each spring the silty Rhine water slipped over the low dykes and
into the forests, meadows and fields of the flood plain.

However, the split channels and snaking meanders prevented the passage of
all but the smallest boats, and building was difficult on shifting river
banks. ‘The river was quite a nuisance,’ says Peter Larsen of the Institute
of Hydraulic Structures at the University of Karlsruhe. ‘The border with
France moved whenever a flood passed,’ he explains, ‘as the main channel
defining the border shifted.’ So Tulla forced the furcation zone into a
single, well-defined channel. ‘As a rule,’ he said, ‘no stream or river
needs more than one bed.’ Nature never intended that this should be so, but
Tulla’s maxim has since become the rule that river engineers follow.

The rectification conveniently prepared the Rhine for its role as the great
river highway of the state of Germany that was created in 1871. Along its
banks grew the great industrial cities of the new Germany, such as Mannheim,
Koblenz, Cologne and Dusseldorf.

This was the beginning of the ecological decline and hydrological
disruption of the river. More than 2000 islands in the furcation zone
disappeared. The new, straight upper Rhine was also about 100 kilometres
shorter than the old river and it flowed 30 per cent faster. The result was
the disappearance of most of the sluggish backwaters and shallow gravel
reaches in which wildlife had flourished.

While Tulla’s plan kept high dykes well back from the river, so maintaining
a broad flood plain, farmers added their own dykes nearer the stabilised
river to turn seasonally flooded pastures into arable fields. Between Basel
and Strasbourg in the past 60 years, the river has been refashioned for a
second time in a scheme designed to capitalise on its navigation and
hydroelectric potential. Tulla’s version of the Rhine (now known as the Rest
Rhine) has been largely abandoned in favour of an entirely engineered
channel, complete with giant locks and a series of hydroelectric plants.
This has cut off the upper Rhine from 160 square kilometres of its flood
plain, leaving just 10 per cent of the original area available to the river.

The faster river sped barge traffic to the sea, but it also scoured the
river’s bed and banks much more fiercely. In the past 100 years, the
riverbed at Basel has fallen by seven metres, the height of a two-storey
house. At the port of Duisburg, the largest inland harbour in the world,
which lies 300 kilometres downstream from the end of the engineering works,
the level dropped by almost four metres. As the riverbed fell, so did the
water table in the alluvial flood plain. Ancient forests of oak, elm and
willow dried out, and wells ran dry.

A second effect of these developments has been to halve to just 30 hours the
time it takes for the spring flood peak to pass out of the Alps, through
Basel and as far as Karlsruhe. After storms over the upper catchment, the
peak flow on the Rhine itself now coincides with those in tributaries such
as the Neckar as they meet the main river. This creates a flood surge that
rushes downstream towards Bonn and Cologne, where there were several record
river flows during the late 1980s. Peak flows are 35 per cent higher than
before 1955, says Larsen. Floods that previously were likely once every 200
years can now to be expected every 60 years.

A third effect of the artificial embankments on the remade Rhine has been to
prevent the river collecting silt from its former flood plains. This
reduces the supply of sediment downstream and increases the river’s ability
to pick up material from the river bed farther downstream. The old, slow,
silty stream that laid down alluvium as it went has been turned into a fast,
silt-starved river that scours its bed, in places by up to 8 metres. Almost
two centuries of efforts to ‘tame’ the Rhine have made it wilder and more
unruly.

Engineers want to reduce the impact of scouring by dumping gravel into the
river. Up to 500 000 tonnes would be needed each year, to be obtained either
by dredging it elsewhere in the river or from gravel pits in the flood
plain. These pits would further combat floods by creating a dozen ‘flood
retention basins’ beside the Rhine. Rather than see these basins become
barren receptacles for flood water, ecologists hope to forge an alliance
with engineers to revive the flood plain.

In Baden-Wurttemberg, the first region to plan flood retention basins, the
ecologists’ case has been partly developed by George Rast, a former
engineer who now works at the World Wide Fund for Nature’s institute for
flood plain ecology at Rastatt. Here the Rhine runs between concrete-lined
banks flanked by high dykes. But down the road is the Rastatter Rheinaue, a
river-side nature reserve with roe deer, wild boar and a pervading whiff of
wild garlic.

Rast claims the Rastatter Rheinaue is the finest surviving flood plain
forest in the whole of the upper Rhine. The waters that flood it are now
controlled by engineers, but Rast hopes that the river will be allowed to
take over again. ‘We want to give back to the remnants of the flood plain
their former role as flood retention reservoirs. From here past Strasbourg
to Neuenberg, wherever it will not endanger people, we want to lower the
dykes and let the flood plain ecosystems reassert themselves.’

Rast hopes to turn 75 square kilometres of expensively drained land,
protected by dykes, into near natural landscape. But house builders and
farmers want the dykes retained, and so the regional government will instead
set aside areas enclosed by dykes into which engineers will be able to
divert flood waters. Now the argument revolves around the flow rate at which
water will start to be diverted. According to Larsen, this will generally be
1500 cubic metres per second, the amount the region’s hydroelectric power
plants need when working at full capacity. But this will mean that
diversions into the flood retention areas will take place too infrequently
and too violently for a flood plain ecosystem to redevelop. ‘If we did it
above 1000 cubic metres, you would get a fairly natural flood,’ says Larsen.

Ideas about the rehabilitation of the Rhine have become far more
sophisticated since the simple campaigns against pollution began in the
1970s. These campaigns intensified after a chemicals spill from the Sandoz
factory in Basel, Switzerland, in 1986, turned the water bright red and
killed half a million fish. This accident prompted the Rhine nations to
launch the Rhine Action Plan with the aim of coordinating efforts to clean
up the river. But the cleanup has proved harder to accomplish than
expected – and much less effective in reviving the river’s ecology.

Many large companies have spent heavily to reduce their pollution of the
river. Since 1974, the chemicals giant BASF has cut the pollution load from
its vast factory complex at Ludwigshafen by around 90 per cent. Most cities
now have treatment works for their sewage, and building them cost Germany
alone some DM60 billion (about £24 billion at current
rates) during the 1970s. Average oxygen levels in the Rhine at Koblenz have
doubled since 1970, largely because less sewage goes into the river.

For major pollutants such as cadmium, mercury and toxic organic compounds,
the target has been to reduce emissions by between 50 and 70 per cent within
10 years from 1985. In many cases these targets have already been met, but
others are proving a tougher proposition. Most of the remaining pollution –
including widely used solvents and farm fertilisers – comes in runoff from
city streets and fields. Many of the estimated 2000 polluting chemicals in
the river are barely known about, let alone routinely monitored. ‘This
diffuse pollution means that we will not be able to meet the limit values
set in the Rhine Action Plan for a significant number of chemicals,’ says
Joost de Jong of the Dutch Institute for Inland Water Management.

It is not only the water of the Rhine that is polluted, but the riverbed
too. Over the years, massive amounts of poison have adhered to silt in the
river and accumulated on the soils of its flood plain. This is a particular
problem in the delta region of the Netherlands, where the river deposits
large amounts of polluted silt as it approaches the sea.

The Dutch authorities dredge their waterways and harbours to keep them clear
for shipping. Traditionally, they have used the silty dredgings for land
reclamation. But around half of the sediments tested by their scientists
fail new pollution limits for sediment destined to be spread on the land.
To cope with the material, the Dutch have constructed two giant, sealed
dumps on the coast. Together they will be able to hold 150 million cubic
metres of silt – enough space to last until 2002.

Nowhere along the Rhine has the switch in thinking towards ecological
rehabilitation of the river been more marked than in the Netherlands – a
nation largely created by engineers pushing back rivers and the sea. Most of
the west of the country, including its largest cities and much of its
farmland, is below sea level, protected from flooding by a network of dykes
and pumps. If you come across a hill in this flat landscape there will
almost certainly be a river at the top, riding high on a thick bed of silt.

For a thousand years the Dutch have reclaimed marshes, pumped dry thousands
of lakes and erected dykes to keep sea and river water at bay. But now they
are doing the unthinkable – bulldozing holes in their dykes and flooding
fields. And they are encouraging their straightened and embanked rivers to
form backwaters and penetrate the surviving marshes. The Dutch government’s
Master Plan for Nature was set in motion in 1990, when ecologists breached
the first dyke, at Duursde Waarden, a 120-hectare nature reserve of marsh
and willow forest on the flood plain of the River Ijssel, one of three main
routes that the Rhine takes to the sea. Progress so far is slow. But
eventually they want to give up to 15 per cent of the Netherlands’ farmland
back to the flood.

At Sint Andries, on a windswept stretch of flood plain beside the Waal –
another of the Rhine’s delta waterways and one of the busiest shipping
routes in the world – government ecologist Havinga Havinga wants to allow a
small portion of the river’s flow to form a backwater parallel to the main
stream. The aim is to provide a quiet, slow-flowing refuge for fish and
plant life, sheltered from the heavy wash of shipping plying the main river.
The overhanging trees, reed beds, silt banks, pools and marsh of a backwater
soon generate a complex, functioning ecosystem, which has an impact on
fisheries, bird life and the wider river system. Havinga says that his main
problem has been with the country’s powerful navigational interests, who
fear that such a breach of Tulla’s dictum will cause the main channel to
silt up.

At present, the river’s fast flow makes the survival of larger aquatic
plants impossible, and fluctuations in water level dry out the banks,
banishing bank species such as pondweed. Instead, impoverished communities
of the few species that can survive the conditions, such as water lilies,
dominate the river, its bank and flood plain. Havinga is proud of some new
stands of willow trees growing beside the Waal a few kilometres downstream
from Sint Andries, a demonstration of how nature could protect the river
banks from erosion just as effectively as the stone armour favoured by river
engineers.

All over the delta region of the Netherlands there are similar initiatives
to revive the ecology of the rivers and their banks, and in places to
re-create the wider flood plain, complete with flooded forests and meadows.
On the Ijssel, 90 per cent of the river bank has been covered with stone
during the past 30 years. But local ecologists intend to replace the stone
with willow trees and bulrushes, and to allow the river to flood the
pastures behind the banks. Previously extinct species such as the mayfly
have already returned to the Dutch delta region, and the bird population
along the Ijssel is recovering.

For the Dutch, like the Germans, the key to reviving the Rhine is no longer
pollution control. ‘Improved water quality isn’t enough. It won’t cause the
salmon, for instance, to return,’ says Anne Schulte-Wulwer-Leidig of the
secretariat of the International Commission for the Rehabilitation of the
Rhine. ‘It requires the restoration of habitats for plants and animals. We
need to re-create the natural flood plains.’ But diverting river waters into
nature reserves can be a mixed blessing. At the Duursde Waarden wetland,
some plant species have disappeared since the dirty water from the Ijssel
was allowed back in. Indeed, most of the Rhine flood plain in the
Netherlands is polluted. Typically, the contamination is worst in the flood
plain soils and backwaters farthest from the river, where the flow is not
strong enough to flush away the poisons.

Outside Arnhem, the local authority is recreating an old wetland, the
Meinerswijk, on the clay and sand banks on a bend in the Rhine. Willows and
poplars are being planted with the aim of re-creating a wild wood within ten
to twenty years. But some of the soils on which the wetland is being
constructed are contaminated with chemical residues carried down by the
river. The authority wants to move the soil to prevent it poisoning the
wildlife. But Dutch national rules on contaminated soils, designed to force
industrialists to clean up the mess they make, mean the soil cannot be
moved. Meanwhile the national river authorities say that the area cannot be
flooded if that will sweep the pollution back into the river. So for the
moment, there is an impasse.

The rehabilitation of the Rhine is proving harder than anyone imagined.
‘There is no point trying to get back the river we had a century ago,’ says
de Jong. ‘The past may be used as a reference. . . but the heavy task will
be to fit in these elements into a river system with new constraints.’

Nonetheless, the Rhine is the first major European river where restoration
has gone beyond pollution control to a planned ecological revival. The
lessons learnt are certain to be adopted elsewhere on the continent, from
the Clyde to the Danube.

* * *

A RIVER FIT FOR SALMON

The Rhine is hostile to much wildlife, in-cluding salmon. Female salmon,
returning to the river of their birth after years at sea, must bury their
fertilised eggs in the gravels of shallow streams, where the water is cool,
fast-flowing and rich in oxygen. The Rhine’s numerous weirs and barrages
prevent this migration, so fish ladders are being built round them in a
programme costing DM10 million ( £4 million) that is being
funded by the European Community. But fish swimming upstream will still find
that most of their former spawning grounds have disappeared.

Once hatched, salmon fry require access to slow-flowing waters in which to
grow. But these nursery habitats, too, have largely disappeared in the Rhine
and its tributaries. According to Anne Schulte-Wulwer-Leidig of the
secretariat of the International Commission for the Rehabilitation of the
Rhine, just 14 hectares of spawning grounds remain on the Sieg, which used
to be an important salmon river, and 4.5 hectares on the Sauer in
Luxembourg. Alexander Raat of the Dutch Organisation for the Improvement of
Inland Fisheries, says that in the upper Rhine itself ‘only one in every
thousand former gravel beds for spawning and nurseries are left’.

In Switzerland, fishermen once depended on salmon for their livelihood. A
century ago an average of 150 000 of the fish were caught each year in the
Netherlands and Germany. The catch had fallen to under 30 000 by 1920 and
disappeared entirely after 1958. Since the mid-1980s, when experimental
restocking of the Rhine began, a handful of salmon have been discovered
swimming upstream. But tags revealed that most had escaped from Norwegian
fish farms. Last year, 15 were found. ‘But none, I think, have come from the
Rhine system and returned,’ says Raat.

The return of the salmon by the year 2000 is the principal target for the
Rhine Action Plan. But there is a growing dispute about whether it is
feasible to re-create a river fit for migrating salmon. ‘We shouldn’t put a
lot of effort into ensuring migration,’ Raat believes. ‘The main river is
not and will not form a continuum. You could instead catch returning fish in
the estuary and take them to the tributaries.’ But for others, anything less
than a river system fit for salmon to swim up and reproduce in will be a
failure.