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Environment: Study Says Tree Loss Not Linked to Major Floods

Posted on: Friday, 14 October 2005, 21:00 CDT

By Jim Lobe

WASHINGTON, Oct. 13, 2005 (IPS/GIN) -- Despite conventional wisdom, deforestation and the local populations that may be responsible for it should not be blamed for catastrophic floods that have wreaked serious human and economic devastation in Asia and Central Europe over the past few years, and most recently following Hurricane Stan in Central America, according to the U.N.'s Food and Agriculture Organization (FAO).

All too often, politicians and the media have pointed the finger for catastrophic flooding at upland small farmers and loggers, according to a new FAO report, "Forests and Floods: Drowning in Fiction or Thriving on Facts?" Their relative poverty and political impotence have made them convenient scapegoats for the sufferings of flood victims downstream.

But there is no scientific basis for such a conclusion, according to the report, which was also sponsored by the Center for International Forestry Research (CIFOR) based in Bogor, Indonesia.

"Government decision makers, international aid groups, and the media are often quick to blame flooding on deforestation caused by small farmers and loggers," said Patrick Durst, senior forestry officer for FAO's Asia and the Pacific headquarters in Bangkok.

"The conclusion is not only wrong scientifically, but such misguided views have in the past prompted governments to make life harder for poor farmers by driving them off their lands and away from the forests, while doing nothing to prevent future flooding," he added.

The convention wisdom -- that deforestation of upland areas contributes heavily, if not causes, major flooding downstream -- is based on the so-called "sponge theory" that appears to have been developed by European foresters toward the end of the 19th century.

According to the theory, the combination of forest soil, roots, and litter acts as a giant sponge, soaking up water beneath the soil during rainy periods and thus preventing it from running off into streams and swelling rivers that devastate towns and cities located downstream.

While the study concedes that local forests and their soils are indeed capable of reducing runoff, that is the case only for "small- scale rainfall events" that are not responsible for the severe downstream flooding.

Severe flooding normally takes place after the forest soil becomes saturated and water can no longer penetrate its surface, according to the report which is based primarily on a review of the scholarly literature. Rather than the mere presence of trees, the key factors include the depth of the soil, its structure, and level of saturation.

"Planting trees and protecting forests can have many environmental benefits, but preventing large-scale floods is not one of them," said CIFOR director-general David Kaimowitz.

He pointed to the lack of evidence of a link between deforestation and major flood events.

"If deforestation was causing floods, you would expect a rise in major flood events paralleling the rise in deforestation, but that is not the case. The frequency of major flooding events has remained the same over the last 120 years going back to the days when lush forests were abundant," he said.

What has changed much more over that period, according to the study, is the much larger number of people who live and work in flood pains and hence the much greater human and economic cost of severe flooding when it takes place. These, in turn, have given the impression that floods have become more severe over time.

Indeed the growth and expansion of cities downstream have transformed formerly agricultural land or wetlands into impermeable surfaces with a very limited, if any, capacity to store water. Many of these had historically acted almost literally as sponges that absorbed the strength and ferocity of rain-swollen rivers.

"Today's floodplains bear little resemblance to yesterday's floodplains, and it should not be a surprise therefore that even minor floods can nowadays cause major damage," according to the report, which notes as well that downstream residents tend to be more politically powerful than the people who live upstream.

"Instead of pointing to distant uplands as the source of their problems and dwelling on fictional cause-effect relationships, lowlands (including policy-makers) should learn to live with rivers and manage the lowlands for what they are -- floodplains," the report concludes.

"We need to stop blaming people who live and work in and around forests for floods that affect entire river basins, and instead consider the effect of a wide variety of land-use issues, which can in some instances include poor logging techniques," said Pal Singh of the World Agroforestry Center, which collaborated on the project along with the International Water Management Institute and the International Center for Integrated Mountain Development.

While sound watershed management and sustainable logging and farming practices in upland areas should still be considered important for other environmental reasons, policymakers and the press should not fool the public or themselves into thinking that measures such as logging bans and forcible resettlement will reduce the dangers of flooding.

Logging bans imposed after flooding in China, Thailand, and the Philippines put millions of people out of work and forced farmers -- often referred to as major perpetrators of "illegal logging" -- to abandon their lands.

"The outcome is that intended results are rarely achieved, but scarce funds are misallocated and unnecessary hardships are heaped on those segments of society that become scapegoats for flood- related disasters and damages," the report asserts.

"Politicians and policymakers should top chasing quick fixes for flood-related problems and promote integrated watershed and floodplain management," said Kaimowitz.

Patrick McCully, executive director of the International Rivers Network, agrees.

"The overall message of this report is a critical one -- we need to move to intelligent management of watersheds and floodplains and away from the failed approaches of 'flood control' based on dams, embankments and upland reforestation," he told IPS.

"But it is unfortunate that this report which rightly aims to combat simplistic views of the causes of major floods is being spun by the media to imply there is no link between watershed degradation, landslides and floods."

Source: Global Information Network

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