Philippine Engineering Journal, Vol 33, No 1 (2012)

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Mario A. Soriano, Peter Paul M. Castro


The Ifugao Rice Terraces was included among the living cultural landscapes in the UNESCO World Heritage List in 1995. However, in 2001, it was reclassified under the World Heritage In Danger List. Climate change has started to impinge on the 2,000-year-old landscape, causing reduced water availability and increased occurrences of water shocks. This study assessed various water resources engineering aspects of the IRT in an effort to ensure its resilience.

A water balance model was developed to characterize water use at the paddy level. The model can estimate irrigation requirement, or the quantity of water that must be supplied to satisfy the consumptive use of crops. It can also determine the miscellaneous water requirements not provided by precipitation and water stored in the soil. The model can calculate IR for different stages of crop growth in dry, normal, and wet years. Simulations showed that irrigation requirement was highest from March to April and lowest from August to September. Excess in precipitation may occur during wet years or extreme rainfall events. This emphasizes the importance of proper control of drainage canals and spillways to minimize runoff in the dry season and prevent oversupply in the wet season.

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