243 years of reconstructed streamflow volume and identification of extreme hydroclimatic events in the Conchos River Basin, Chihuahua, Mexico

Key message The extreme hydroclimatic events in the Conchos River Basin, are strongly associated with ocean-atmospheric phenomena such as the El Nino Southern Oscillation, Pacific Decadal Oscillation, and Atlantic Multidecadal Oscillation, the streamflow reconstruction showed the occurrence of up to 10-year droughts. Dendrochronology is a modern science used to study hydroclimatic events through the measurement and standardization of tree-rings. Long-term dendrochronological series contribute to the improvement of our knowledge of past climatic events and provide information for wise management of water resources. The objective of this study was to generate an actualized streamflow volume reconstruction with a regional chronology and identify extreme hydroclimatic events in the Conchos River Basin. We analyzed the hydroclimatic behavior of the streamflow volume through a dendrochronological network in the Basin. The regional earlywood chronology was analyzed by single correlation and principal component analysis, which allowed obtaining the transfer model to determine extreme hydroclimatic events and defined the influence of large-scale ocean-atmospheric phenomena. Nine earlywood series showed a common variance and responded significantly (r = 0.68,n = 67,p < 0.05) to the water volume accumulated in the November-June period measured the water inflow to the Boquilla Dam. From that correlation, a 243-year (1775-2017) streamflow reconstruction was made. The hydrological analysis of the reconstruction showed the occurrence of up to 10-year long drought-from 1948 to 1957-and a period with maximum moisture between 1983 and 1994 with a probability of occurrence of 4.16% (24 year frequency). We found significant correlations between the reconstructed streamflow volumes and the Southern Oscillation Index (r = 0.52,p < 0.05,n = 203); Multivariate El Nino Southern Oscillation Index (r = 0.32,p < 0.05,n = 68), the Pacific Decadal Oscillation (r = 0.39,p < 0.05,n = 118), and the Atlantic Multidecadal Oscillation (0.32,p < 0.05,n = 70). The observed correlations with the drought indices such as the Palmer Drought Severity Index and Standardized Precipitation Evapotranspiration Index were also significant (r = 0.75,r = 0.77,p < 0.05, respectively). Our historical reconstruction of streamflow in the Conchos River basin contributes to a better understanding of the frequency of extreme hydroclimatic events affecting water availability in this binational basin.