Assessment of Agricultural Drought using Satellite-Based Indices in the Philippines

Agricultural droughts caused a major problem in the agriculture sector. It is associated with a shortage of water available for crop growth that leads to yield loss. Several studies were conducted to determine appropriate indices to be used in assessing agricultural drought severity and duration. A drought index should integrate various parameters such as rainfall, temperature, evapotranspiration (ET), runoff, and other water supply indicators that impact crop growth and development during incidences of drought for operational decision making in the agricultural sector. In the Philippines, monitoring and forecasting of agricultural drought have been focused recently due to its big impact on the livelihood loss of farmers. But the recent studies have its limitation regarding on assessment of this phenomenon that is recurring and mainly affected by climate-changing patterns. To address issues in the assessment of agricultural drought especially on the Western Visayas region, the idea of vulnerability mapping was introduced using remote sensing data and GIS-based processing techniques. The study aims to identify the sensitivity of drought indices such as Enhanced Vegetation Index (EVI), Vegetation Health Index (VHI), Evaporative Stress Index (ESI), and Leaf Area Index (LAI) and evaluate the performance of these indices with regards to recent actual drought conditions. Using satellite-based imagery provided by the National Aeronautics and Space Administration (NASA), Land Processes Distributed Active Archive Center (LP DAAC), U.S. Department of Agriculture’s (USDA) Agricultural Research Division (ARS), National Oceanic and Atmospheric Administration (NOAA), and product distributed by United States Geological Survey (USGS), evaluation of agricultural drought in a local setting was possible for estimation of irrigation requirements and providing necessary information to decision-makers and stakeholders to formulate optimal drought management strategies.