Mapping and modelling of greenhouse gas emissions from rice paddies with satellite radar observations and the DNDC biogeochemical model

Rice is an important agricultural production system with more than 80 million ha of irrigated rice paddies in annual production globally. As water resources become scarcer, the competition between urban development and agriculture for available water will intensify. Paddy rice cropland distribution and management intensity will need to evolve over the coming decades to accommodate increased production demand with decreasing land and water resources. 2. While process-based biogeochemical models can provide important insights into how agricultural management of rice paddies influences water resources, yields and greenhouse gas emissions, they require accurate spatial estimates of the extent of paddy rice cropland and cropping systems. Satellite remote sensing data can provide such spatially explicit information. 3. Data from Synthetic Aperture Radar (SAR) are ideal for mapping rice paddies owing to its nearly all-weather imaging capabilities and sensitivity to flooded vegetation. 4. This paper presents a framework for combining routine SAR observations, GIS databases and a process-based biogeochemical model for a decision-support system for mapping and monitoring rice paddies. This framework is demonstrated for a site in India under a range of alternative water management strategies.