Can Forests Protect Us From Floods?

Foto Wahana Lingkungan Hidup Indonesia (Walhi) Sumatra Utara

February 9th, 2006 / Opinion / Can forests protect people from disaster?
Source: The Jakarta Post, Didy Wurjanto, Jakarta

Foresters and environment groups have frequently blamed deforestation, especially that due to logging operations, as the root cause of the recent floods and landslides on Java that have claimed hundreds of lives and incurred huge infrastructure losses. There is a widespread belief that forests can prevent floods by acting as giant sponges, slowing down the surface runoff and soaking up water during heavy rainfall.

However, certain scientists have presented new findings that claim there is no scientific evidence linking large scale flooding and landslides to deforestation (The Jakarta Post, Jan. 6, 2006 )

Although the causes of the tragedies are still under investigation, pro and contra have been debating on whether the disappearing forests have led to the natural disasters in Jember, East Jawa , that killed at 119 people, and Banjarnegara, Central Jawa , that recently took the lives of at least 149 people.

The proponents of the argument that deforestation leads to floods and landslides say that forests are necessary to regulate stream flows and reduce runoff. Reducing forests usually results in increased runoff. Further, they argue that degraded highland forested areas make a significant contribution to the creation of small natural dams as the soil has been compacted and loses its porosity to absorb water from rainfall.

A recent study conducted by FAO and CIFOR (2005), Forests and Floods: Drowning in Fiction or Thriving on Facts?, argued that existing knowledge of deforestation leading to floods and landslide disasters is frequently based more on perceived wisdom than on science. In the rush to identify the causes of the disasters, the study revealed that the assumptions were made simply based on observations from other regions, which often have quite different environmental characteristics, or by extrapolating from small to large scale.

According to this study, forests only have a limited influence on major downstream flooding, especially large-scale events. Forests indeed are capable of reducing runoff as the result of enhanced infiltration. But this is only true for small-scale rainfall events. During a heavy rainfall events, like those that resulted in massive flooding in Jember and Banjarnegara, especially after prolonged periods of preceding rainfall, the forest soil becomes saturated and water no longer infiltrates into the soil but instead runs off along the surface.

Hydrology experts say that within watershed systems, flooding is the natural way to discharge water arising from heavy rainfall. There was no problem with flooding until people decided to use natural flood plains for their own use. This situation forces us to face the fact that people have chosen to live and work in these flood plains.

The key to minimizing potential future disasters is not by abruptly relocating people already living within the watersheds. However, it is vital that fragile areas be identified, classified and protected from inappropriate use, whether this be forestry, agriculture or mining. Nonetheless, even the best plans will not be effective if it is not implemented or facilitated by supportive policies.

Effective watershed management is an iterative process of assessing, planning, restoring and organizing land and resource use within a watershed to provide desired goods and services while maintaining and supporting livelihoods. This process provides an opportunity for stakeholders to balance different goals and resource uses and to consider how the development may affect long-term sustainability of natural resources. Mining and physical infrastructure such as roads can affect local hydrology far more than agricultural practices.

In this autonomy era, several local governments have undertaken preventive measures to protect their people and their infrastructure from similar tragedies. They have launched the concept of Kabupaten Konservasi (conservation regency) by managing the nearby watersheds in the form of conservation area management. The idea is not only to care for the watersheds but also the forest cover.

Amru Daulay, the regent of Mandailing Natal, North Sumatra , led his people to establish the 108,000-hectare Batang Gadis National Park in 2004, which accounts for 26 percent of the forest areas in the regency. The natural park became the center of the surrounding six sub watersheds contributing to the total economic value of more than Rp 160 billion (US$17 million) per year through domestic water, agriculture, fisheries and other environmental services (Conservation International 2006).

The park is responsible for supplying clean water to 13 districts within the regency. Its dense forests are home to very important wildlife including Sumatran tigers, which are now very rare in other parts of North Sumatra . Embedded in the concept of national park management is the recognition of the harmonized interrelationship of many different activities, such as fisheries, urban development, agriculture, forestry, recreation, conservation and other human influences.

Working with other stakeholders the government is striving to find a break-through in creating incentives for those who have an interest in keeping the park functioning.

The writer is an employee of Conservation International Indonesia . He can be reached at dwurjanto@conservation.org.