CAUSES of flooding in Iloilo can be addressed better with correct, appropriate knowledge on the sediment condition-watershed management study, according to Dr. Severo Saplaco, watershed management specialist, and a consultant of the Iloilo Flood Control Project.

He explained first of all, that the watershed should be perceived as a continuum with three “environments” namely, mountain environment, lowland environment, and the coastal or sea environment. It follows that whatever is done in one part of the continuum, affects the other parts.

The Tigum-Aganan watershed is composed of the municipalities of Maasin, Cabatuan, Janiuay, Alimodian, Leon, Sta. Barbara, San Miguel, Pavia, Oton and the city of Iloilo. Its major rivers are Tigum, aganan, Jaro, which are the primary sources of flooding in downstream areas, particularly

In his study on the sediment condition of the Tigum-Aganan Watershed, Dr. Saplaco pointed to three factors contributing to flooding, and these are: rainfall, vegetation management, and soil-water conservation practices.

Saplaco explained that rainfall is a natural phenomenon and one cannot stop it, hence, more rainfall, more chances of flooding.

Management interventions, however, is needed, particularly some kind of information and education strategies that will tell people how to better use rainfall data for flood forecasting, the putting up of more strategic rain gauging stations and the adoption of watershed continuum approach in implementing projects.

Vegetation management, on the other hand, emphasizes that the more vegetation the watershed has, the less run off, hence the lesser water drained downstream. With 10 percent vegetation, about 75 percent will be the runoff which results to flooding because of very poor ground cover, Saplaco also explained.

He cautioned, however, that some misconceptions should be changed, like, forest cannot prevent flooding as there can be flooding even under the best forested watershed. The way the land is used in agriculture as well as tree planting technology bear impact on soil erosion.

The current national policy on 60 percent for agriculture and 40 percent forest land use ratio should be strictly observed, Saplaco stressed.

Likewise, people should understand that it is not necessary to plant only trees on the watershed for runoff, soil erosion and flood control, but planting of high value fruit trees and other crops which can augment income is also recommended.

A keen study of the soil-water conservation practices of people in the watershed area also impact on flood control. Dr. Saplaco observed that terracing has become an indispensable traditional soil-water conservation practice of farmers in the watershed continuum. Further, terraced upland farms are compatible with sustainability of the watershed development and management. Incentives can be provided so that these terracing practices can be enhanced.

In driving home a crucial point, Dr. Saplaco said that much of the efforts in flood control should anchor on the kind of correct, appropriate and simplified information and education campaigns conducted among target audiences in the watershed continuum.

Elsa S. Subong, Philippine Information Agency

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