Annual and warm season drought intensity-duration-frequency analysis for Sonora, Mexico

Located in northwestern Mexico, Sonora is a region affected by the North American monsoon (NAM). The region covers nearly 50% of the North American Sonoran Desert and is characterized by climatic conditions ranging from extremely arid to semiarid. The region has suffered from drought since 1995, and consequently, water supplies are threatened. The objectives of this work are to characterize the spatial and temporal variabilities of precipitation in Sonora and to conduct a meteorological drought intensity duration -frequency analysis based on annual and warm season precipitation records. Monthly precipitation data are compiled from 76 meteorological stations located in Sonora, along with 19 stations in the neighboring American state of Arizona, for the period 1961-2004. For increased reliability, data are pooled within five plausible climatic regions. Among the results reported herein are summaries of precipitation variability, drought frequency estimates for annual and seasonal durations and return periods of 10-100 yr, and an estimate of the return period of the most recent multiyear drought.