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Floods in Bangladesh are getting worse. After they inundated half the
country and as much land again in India in 1987 and 1988, there seemed little
doubt an ecological crisis was happening in the flood plains of the Ganges
and the Brahmaputra. These two great rivers rise in the Himalayas and drain
an area inhabited by 500 million people, a tenth of the population of our
planet.

After the floods, aid agencies queued up to spend money on planting
more trees in the Himalayas. The assumption is that as the forests disappear,
so do the soils of the mountain range. Without soils, monsoon rains rush
with increased ferocity onto the vulnerable flood plains below. The flood
waters carry with them more and more silt that clogs channels and increases
flooding. According to the theory, the Himalayan farmers who cut down the
trees are the ecological villains, responsible for massive loss of life
and property far downstream. But is this analysis correct and will tree
planting end the crisis? The evidence suggests not.

The entire Himalayan region experiences a monsoon climate with enormous
amounts of rain, mostly between June and early October. Cheerapunji in northeast
India is one of the world’s wettest places and has more than 9 metres of
rain each year. The monsoon floods are devastating during years of exceptionally
high flow. In 1988 the flood covered 60 per cent of the country. During
the floods, vast amounts of sediment are brought down from the Himalayas
and eroded from river banks on the plains before being deposited in the
delta and beyond. This process has played an important part in extending
the Ganges-Brahmaputra delta south into the Bay of Bengal and the emergence
of new land. Satellite pictures show plumes of sediment in the Bay of Bengal
several hundred kilometres south of the delta.

But this may be nothing to do with human activity. It happens in large
part because the Himalayas, the world’s youngest and highest mountain chain,
are readily eroded. Rates of erosion are generally proportional to the steepness
and length of the slopes. But they are increased by torrential rainstorms,
by the frequently shattered and faulted nature of the local rocks, and by
the high level of seismic activity, which triggers frequent large landslides.

Silt is deposited throughout the flood plain. In places it is more than
5 kilometres thick. Without this very effective system for the transfer
of water and sediment from the Himalayas, most of Bangladesh and much of
the Indian States of Bihar, West Bengal and Uttar Pradesh would not exist,
but would be arms of the Indian Ocean.

In their natural state, many of the southern slopes of the Himalayas
were, like the plains below, covered by dense forests ranging from subtropical
rainforest to temperate birch, fir, pine and rhododendron. But this forest
cover has been drastically reduced by human intervention over the past 200
years. It has been assumed that what remains has come under increasing pressure
since 1950. The population of Nepal is growing at a rate of 2.6 per cent
per year, according to the latest census (1981) and villagers have an ever-growing
need of wood for fuel and of foliage for fodder. It is widely claimed that
more than half of Nepal’s forest cover has been lost in recent decades,
and with it much of the Himalayan topsoil.

In 1987 the UN Fund for Population Affairs asserted that ‘over the past
25 years, Nepal has lost 30 per cent of its forest cover, mostly to fuelwood
gatherers and subsistence farming. As a result some 80 million cubic metres
of Nepalese soil is washed down to the Bay of Bengal every year.’ The World
Bank, in a report published in 1979, Nepal: Development Performance and
Prospects, claimed that by the year 2000 no accessible forest would remain
in Nepal. The continued loss, through soil erosion, of agricultural land
in the mountains leads, it is said, to another round of deforestation as
farmers construct more terraces on hillsides on which to grow crops.

This apocalyptic vision has led to the view that a few million hill
farmers, through their ignorant abuse of their own environment and their
uncontrolled population growth, are holding hostage several hundred million
people on the plains. The argument has been incorporated into a general
view about the damaging effects of deforestation, including the loss of
lowland rainforests. The world’s forest resources are undoubtedly a key
resource that must be preserved. But we should examine critically claims
about the effects of the clearance of mountain forests on soil erosion and
flooding.

The theory of Himalayan environmental degradation has been developed
and supported over the past 40 years by a long succession of scientists,
environmentalists, development agency experts and journalists, including
myself at one time. Many of us did not spend enough time in the region,
seemed unable or unwilling to learn from the local people, and tended to
reiterate manufactured ‘facts’ that confuse cause and effect. However, in
recent years the theory has been challenged.

For a start, the claim of massive deforestation since 1950 is inaccurate
for many areas for which detailed information is available. Deforestation
in Nepal and other sections of the central Himalayas was already well advanced
by the 1750s, and by the early part of this century, practically all potential
arable land had been converted in the Middle Mountains, the most densely
populated region. Since about 1925, little actual reduction in forest cover
has occurred here. More recently, photographs show that some claims of extensive
loss of forest cover on specific slopes are wrong. Also, most farmers are
knowledgeable about the environment and frequently prevent soil erosion.
They know the risks to their own lands from soil erosion and frequently
repair and re-terrace landslides. It seems that the more people there are
in a region, the fewer the landslides, rather than the reverse as the theory
presupposes.

Deforestation may not necessarily cause soil erosion in the Himalayas.
In most traditional farming systems, tree cutting and conversion of forest
to terraced agriculture may conserve the soil more effectively than leaving
the forest in its original state. In the Himalayas, cutting and carrying
of wood is usually done by hand and forested slopes are replaced by terraces.
So soil loss may be reduced by the arrival of farmers on a hillside. We
cannot assume that reforestation will reduce either soil loss or flooding
downstream.

If links between land use, soil erosion and river flow are hard to demonstrate
in the hills, the task is harder still when looking for effects downstream
on the heavily populated plains of India and Bangladesh. Recent analysis
comes from groups supported by, among others, the United Nations University
Project in Nepal, the Nepal-Australian Forestry Project and the International
Centre for Integrated Mountain Development (ICIMOD) in Kathmandu. No clear
link has been established between changes in land use in the mountains and
changes in the flows and transfer of sediment in the Ganges and Brahmaputra
on the plains. It seems highly probable that the plains often flood simply
because of the torrential rainstorms there, rather than because of natural
or artificial events in the hills. Even if large scale reforestation in
the mountains reduces the flow of monsoon water locally, the effects would
be hard to detect on the plains. In the study for ICIMOD, researchers calculated
that if all cultivated and grazing land in the Nepalese Middle Mountains
were to be reforested, the flow might be reduced by about 35 per cent locally.
But the effect on the flow of the Ganges would be something like 3 per cent.

Claims that the 1988 flooding of Bangladesh was the worst this century,
that flooding is becoming progressively more se-rious, are, like the claims
about soil erosion in the Himalayas, unsupported. Emotional arguments are
frequently used for dubious political ends. Since the mid-1970s, Nepal has
received large amounts of aid to plant forests, while taking revenues from
commercial exploitation of its lowland forests. Perpetuating the myth that
its peasant hill farmers are causing widespread ecological damage ensures
the aid continues. Ironically, the aid agencies seem unconcerned that Nepal
is felling huge areas of forest on the plains while complaining of the ecological
damage that deforestation is causing in the hills. Many environmental groups
have inadvertently connived in pillorying subsistence farmers who are unable
to answer back.

Similarly, Bangladesh is about to embark on a massive flood project
employing large civil engineering works that may eventually cost billions
of dollars-all paid for with loans and grants from the World Bank and Western
aid agencies. Instead, the aid agencies could have supported a less grandiose
plan based on traditional engineering techniques. This would have been less
expensive and not threatened the local ecology and environment to the same
degree (see ‘The rivers that won’t be tamed’, this issue).

It seems essential that major engineering proposals be independently
assessed. Such a task could well fit the agenda of the forthcoming United
Nations Conference on Environment and Development, to be held in Rio de
Janeiro in June 1992. Furthermore, a major effort should be made to consult
the wishes of the people who would be most affected-the farmers of the Himalayas
and their counterparts in the flood plains below. Without a great deal of
new thinking it is quite possible that a lot of money will be spent for
little gain in the lives of those whose needs are the greatest.

Jack D. Ives chairs the Department of Geography at the University of
California. Davis and is coordinator of the Mountain Ecology and Sustainable
Development Project of the United Nations University. Fred Pearce is an
environment journalist.