Precipitation patterns in Usumacinta and Grijalva basins (southern Mexico) under a changing climate

The Usumacinta and Grijalva basins of Mexico are characterized by their high water and natural wealth. They gather a great part of the biodiversity and are responsible for 30 % of the total surface runoff in Mexico. However, southeastern Mexico is recognized to present a high degree of socioeconomic vulnerability and climatic risk. Thus, since climatic data in tropical zones are scarce for climate knowledge and understanding, it is essential to analyze changes in precipitation patterns as a critical variable of climate. The present study analyzed the behavior of precipitation patterns using the Standardized Precipitation Index (SPI) for the period from 1960 to 2016 in the Grijalva and Usumacinta basins. Wet events were confirmed to occur during negative phases of the Pacific Decadal Oscillation (PDO) and the El Nino Southern Oscillation (ENSO), whereas dry events occurred during their positive phases, respectively. In addition, the basins have been subjected to different environmental degradation processes, observed to a greater or lesser extent in each of the basins and parts of the countries involved. Thereby, climate change did not represent the only pressure on the natural resources of the area, since intense processes of degradation of vegetation cover and deforestation, among others, have been observed, and this pressure can be exacerbated by the effects of climate change.