Experts divided over cause of worsening Bangladesh floods

[senorpepr]

DHAKA (AFP) - Bangladesh has been hit by increasingly severe floods in recent years but experts remain divided over whether deforestation in Nepal is to blame for the inundation of this low-lying South Asian country.

Flooding that hit Bangladesh more than a week ago has submerged large parts of the country and left up to four million people marooned, many without fresh water, shelter or food.

But although most experts agree that flooding appears to be increasing in severity, some say it is only marginally worse than in previous decades, and the cause of the increased flooding is also the subject of debate.

"Bangladesh will always and has always suffered floods but it is the deforestation that is the main contributing factor in the severe floods of recent years," said Mohammed Ali Bhuiyan, water resources expert at Bangladesh University of Engineering and Technology.

"After deforestation, the top soil from mountainsides is carried downstream from Nepal and eventually the sediment is deposited on riverbeds in Bangladesh. That decreases the depth of the river so they can carry less water and are more prone to flooding," he said.

But critics of this theory say random variations in the intensity of monsoon rains cause the flooding.

They point to a United Nations Environment Programme finding that forest cover in Nepal fell only nine percent between 1979 and and 1994, not enough they say to cause an increase in flooding.

Deforestation is only one of a number of factors that might have aggravated flooding in recent years but the main cause is heavy monsoon rains, they say.

"When rains are not staggered over each month and happen over just a few days, simultaneously across many parts of the country, we get severe flooding," Mohammed Salim Bhuiyan, of the Flood Forecasting Warning Centre, told AFP.

Bhuiyan said the severity of recent floods had increased slightly and deforestation was only one of the factors involved.

"The floods are a little worse but the number of people being killed or made homeless is higher because of the overcrowding we have in this country that forces people to live in areas prone to flooding; before when there was less pressure on land they would not have lived in those places," he said.

Other factors included increased use of agricultural land for urban development.

Water runs off land covered in roads and buildings quicker than it drains off agricultural land, making flooding more likely.

Bangladesh, one of the world's poorest nations, is criss-crossed by a network of 230 rivers, some of which carry melting snow from the Himalaya before emptying into the Bay of Bengal. \

Historical records have allowed meteorologists to study floods in Bangladesh back to 1781, showing that a major flood could be expected every seven years and a catastrophic one every 33-50 years.

More detailed records since 1954 show the worst flooding since then occurred in 1974, 1987, 1988 and 1998, when 70 percent of the country was submerged in the most serious flood Bangladesh had ever seen.

Flood control measures in Bangladesh rely heavily on the use of earth embankments along rivers.

In 1990 the country adopted a "Flood Action Plan" under which 9,143 kilometres (5,668 miles) of earth embankments were built as flood defences.

Critics say the embankments narrow and accelerate water flow and are of dubious benefit as they are easily breached.

Dilruba Haider, of the United Nations Development Programme's Dhaka-based disaster management unit, said the combination of monsoon rain and major rivers draining through Bangladesh meant flood prevention was ultimately unachievable.

Her unit instead concentrates on reducing risk by helping villagers build dwellings and farm crops less easily damaged by floods.

"I doubt that a solution to flooding in Bangladesh will ever be found," she said.

"Rather than try to stop the unstoppable we try to teach people to live through floods so that they have less impact on their lives."