Regional drought frequency analysis based on L-moments for the Rio Grande River Basin, Mexico

Abstract

In order to determine the characteristics of meteorological drought periods that occurred in the Rio Grande River Basin in the 1984-2013 period, a regional frecuency analysis based on L-moments (RFA-LM) was conducted. The analysis used precipitation records from 90 weather stations, which were subject of a quality control and data homogenization process. Through an iterative process, five homogeneous regions (HR) were identified according to the annual mean precipitation criterion. The probability distribution functions that best fitted the records were Gaucho (HR1) and Generalized Logistic (HR2 to HR5). Based on these functions, quantiles (annual precipitation values associated with a certain occurrence probability value) were determined, as well as precipitation deficit maps with 5, 10, 15, 20, 50 and 100 years return periods. The results indicate that meteorological drought events occur in the river basin with an average duration between 1.7 and 2.5 years, and with an average recurrence of 3.9 to 4.5 years; the longest drought period occurred between 1993-2002, and the period with the highest rainfall deficit was 2011-2012. The most affected regions are located in the states of Chihuahua and Coahuila, where the decrease levels in precipitation can exceed 80 % of deficit, which indicates that for a return period of 100 years, more than half of the basin would show an extraordinary drought degree, which would have serious repercussions for the different socioeconomic sectors.