Reconstructed volumes in dams of the Valle del Yaqui with annual rings of conifers

Abstract

A dendrochronological network of early and late-wood and full ring of Pseudotusga menziesii was developed for the upper basin of the Yaqui river (CRY) to explain the historical runoff volumes recorded in the basin and sub-basins feeding three of the largest dams (Angostura, Novillo, Oviachic) in the State of Sonora, which supply water annually for about 250 000 ha. The chronologies showed an inter-annual and multi-annual climate variability (r >0.60, p< 0.01), suggesting the influence of common weather phenomena; situation that allowed them within a regional chronology of 479 years (1534-2012) in length. The regional chronology of earlywood responded to the accumulated rainfall from February to May and runoff volumes from October to June, representing 43% of the annually registered in the CRY. Both variables were correlated (r= 0.83, p< 0.01, n= 479), suggesting that the annual runoff has high influence of the winter-spring precipitation. At sub-basin level, the dendrochronological series showed a significant association with the volumes recorded in the respective dams, but the limited number of series prevented a more complete analysis of the hydroclimatic variability, so it is important to expand it. ENSO was the phenomenon that affected the most the variability in rainfall and runoff of the winter-spring period. The association between regional chronology of early-wood and the Southern Oscillation Index (SOI) was negative, but significant in the winter (r= -0.59, p< 0.01), implying high influence of the warm phase of this phenomenon in the natural climate variability.