Drought monitoring is normally based on climatic data which often lack the full spatial coverage and immediate data availability, requiring long time for analysis. Rapid access to satellite data offers an alternative for identifying drought patterns which are manifestation of meteorological and hydrological droughts. The objective is therefore to explore drought patterns using vegetation indices as related to drought conditions. The study area, Northeast Thailand, covers an area of about 170,000 sqkm and is characterized by gently undulating topography with diverse crop and forest types. The Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI) and Normalized Difference Drought Index (NDDI) of the Terra-MODIS acquired in 2001-2008 were used to identify the surface state in relation to the corresponding rainfall data. Establishment of a relationship between the rainfall derived data and the indices was performed to identify a spatio-temporal pattern of drought With the relationship established, the spatio-temporal drought patterns could be predicted from the satellite-derived data. The NDVI, NDWI and NDDI indices provide information on drought condition and is found to be more effective compared to the use of the conventional method. The information obtained can be used in decision making for land being planted to crops.
展开▼
