Large-scale climate indices teleconnections with hydrochemical and isotopic characteristics of a karst spring using wavelet analysis

Abstract

This study investigated the large-scale El Nino–Southern Oscillation and Pacific Decadal Oscillation indices teleconnections with the spring chemographs and δ18O time series in the Sarabkalan Spring, Zagros Mountains, Iran. It was intended to document a karst system by identifying synchrony and coupling between climate indices and its precipitation, spring discharge, chemographs, and isotopes. Here, we used the continuous wavelet transform and wavelet coherence. The findings demonstrated that El Nino Southern Oscillation is more correlated with EC, Ca + Mg, K, and Cl while Pacific Decadal Oscillation is largely teleconnected with EC, Na, and K. Also, the El Nino phenomena coupled with either positive or neutral Pacific Decadal Oscillation phased appeared to cause a decrease in δ18O. It is further found that in addition to its quick pulses in the spring, intense precipitation can also substantially affect the spring discharge even up to ~ 1.5-years later. The discharge and physicochemical parameters of EC, HCO3 + SO4, HCO3, Mg, and Na are out of phase, indicating that the constituent concentrations generally decrease over wet years of high discharge. This work highlighted the necessity of a combination of hydrogeological and climatic-oceanic-atmospheric factors from the local to global scales to improve water resources planning and operations in karst water resources.