Drought is a slow-onset disaster that affects agriculture and associated livelihoods in many parts of the world. Drought stresses vegetation; therefore, the extent of a drought can be reflected by changes in the state of vegetation. Geospatial scientists have developed drought indices based on remote sensing data to effectively detect drought conditions. Normalized Difference Vegetation Index (NDVI) is the normalized difference between near infrared (NIR) and red reflectance. Simple and effective, it is one of the most widely used indices for detecting drought conditions. More recently, many other indices have been developed, such as the Vegetation Condition Index (VCI), which is an indicator of the state of the vegetation cover according to the minima and maxima of NDVI encountered for a given ecosystem over many years, or again the Vegetation Condition Index (VCI). Health Index (VHI), which combines VCI and Earth surface temperature.
This best practice will use Google Earth Engine for index preparation. Google Earth Engine is a cloud-based platform and can perform large scale geospatial analysis to solve real spatial problems based on open source data. The main advantage of Google Earth Engine is that it uses Google’s vast computing capabilities, resources and datasets, which generally do not require high-performance user-side computing systems. Therefore, Google Earth Engine appears to be a single, integrated platform designed to empower not only traditional remote sensing scientists, but also a much wider audience that lacks the technical capability to use traditional supercomputers or cloud computing resources.