The Southeast Asia (SEA) region, especially Vietnam and Cambodia, has encountered uncertainties/challenges in sustaining the production system of its food and water systems due to climate fluctuations. Despite investments in both structural and non-structural solutions, the lack of advanced methods and techniques to monitor and forecast drought, as well as assess water demand for operationalising the water and food system, is deemed critical from both policy and social perspectives. The utilisation of big Earth data has demonstrated significant potential for application in observing food and water systems. By integrating big Earth data, essential operational parameters can be derived for agriculture, providing valuable insights for policymakers and water resource managers.

The project creates a tool supporting agricultural water management using the water-demand index (WDI) derived from influencing first-order variables, namely soil moisture (SM), vegetative growth (NDVI), and heat factor (growing degree day, GDD). Within the APN Seed grant project, the WDI maps in different periods of a critical drought event (2020) were conducted at weekly and monthly time scales over the two piloting regions of Vietnam and Cambodia. The WDI zoning maps were verified using the ground survey and collected data in Ninh Thuan province and Kampong Thom province to assess their suitability to integrate with irrigation system operations, and inform policy development for regions facing water stress.