Vegetation Index Mapping for Lower Mekong Region
Food security and forest resources are critical concerns in many developing countries, especially because a changing climate increases uncertainties in weather patterns, the water cycle, and water availability. Climate change and an increasing world population put additional pressure on agriculture and forestry. Satellite remote sensing provides information about how vegetated land cover is changing over time due to urbanization, de-forestation, and agricultural practices, and is an effective way to monitor agricultural fields to determine whether current farming practices are producing optimal crop yields or need to be modified.
NDVI (Normalized Difference Vegetation Index) data is of particular importance. It is an indicator, derived from the amount of light reflected by the land surface at two different wavelengths, of the amount and health of vegetation, including crops and forests. Dense green vegetation will have a high NDVI, while sparse or unhealthy vegetation will show lower values.
SERVIR recently provided geo-referenced NDVI for Cambodia, Laos, Vietnam, Thailand, and Burma to the Asian Disaster Preparedness Center (ADPC)-hosted SERVIR hub in the Lower Mekong. The data, from Landsat-7 (c. 2001) and Landsat-8 (c. 2014), was obtained by Stennis Space Center. Stennis also wrote code to calculate NDVI for SE Asia and delivered the data in manageable sizes by geographic sector of the Mekong region. Stennis Space Center scientists will also provide training and deliver the computer code to the ADPC users.
Agricultural officials, urban planners, natural resource managers, forestry service personnel, and others will use the NDVI data to make informed decisions about crops, urban development, forest management, and more.
Future plans include development and delivery of impervious cover data products, that is, non-natural land cover such as buildings and paved surfaces.
Example Landsat-8 derived NDVI products computed for Cambodia
Difference in NDVI from 2001 to 2014 for a coastal region on the Gulf of Thailand