Climate-based suitability assessment for alternate wetting and drying water management in the Philippines: a novel approach for mapping methane mitigation potential in rice production

The alternate wetting and drying' (AWD) technology for rice is a water-saving technology with a high greenhouse gas (GHG) mitigation potential. The Philippine government attempts to disseminate AWD in all national irrigation systems in order to adapt to increasingly scarce water resources.This article describes how a model for climatic AWD suitability assessment developed by the International Rice Research Institute (IRRI) is suited for a national assessment of the Philippines, and country-scale climatic suitability maps for AWD are develop for wet and dry season. Furthermore, how the assessment can be used to estimate potential GHG emission savings is illustrated.Results show that a maximum of 60% of the rice area of the Philippines is climatically suited to AWD, reaching more than 90% in the dry and 34% in the wet season. The potential, maximum annual reduction is around 265,000t of CH4 emissions from lowland rice in the Philippines, or around 15% of the country's annual emissions from the agriculture sector.The article concludes with recommendations on the use of this simple spatial water balance model for mitigation planning which offers a more spatially detailed, quantitative and transparent estimate of national GHG emissions in the rice sub-sector for rice producing countries.