全球变化知识资源中心

An objective methodology for the detection and monitoring of droughts at a regional scale is presented. It is also shown how the drought monitoring can be detected and followed through the independent and joint index combination of the main hydrological (soil moisture), meteorological (precipitation and surface temperature), and vegetation (NDVI and evapotranspiration) indicators. The present methodology considers the information of each one of these variables, and additionally a joint estimation for precipitation and evapotranspiration is considered. Under this principle, it is proposed that the monitoring of droughts can be conducted through five indexes mainly, giving a different weight to each one depending of their spatio-temporal relevance. These indexes are standardized for an easy and practical combination following a weighted algebraic combination, derived from that an Index of Drought Persistence (IPS by its initials in Spanish) is obtained. The value of each one of the weights was determined in function of the relevance obtained through the principal components analysis; thus, it is obtained a single map, named persistence map, for each period considered ranging from one to 48 months. A comparative analysis with the actual and official Mexican Drought Monitor (MSM by its initials in Spanish) shows that the IPS is systematic, though it is complex to precisely determining how much due to the subjectivity that MSM is elaborated. Results from the IPS may be used as primary input for the water and agriculture sectors, but due to its nature and versatility, it is also possible to adapt the methodology to other users or sectors, including for climate change scenarios studies.