Hydrogeochemical processes constrained by multivariate statistical methods and isotopic evidence of groundwater recharge in the aquifer of Figuig, Eastern High Atlas of Morocco

Abstract

In this paper, we present and discuss 72 samples of groundwater (borehole, well, and spring), collected over a period of time of 20 years (i.e., between 1983 and 2004) in the Figuig aquifer. The chemical and isotopic analyses were carried out to improve our understanding of the hydrogeochemical processes. Most of the waters sampled consist of Ca-Mg-HCO3 and Na-K-Cl types. The samples are grouped according to two factors. Factor 1 shows strong negative loadings of EC, Cl-, Na+, Ca2+, Mg2+, and NO3−, K+ with 73.91 % of the total variance (TV); factor 2 shows strong positive loadings of SO4 2−, HCO3− with TV of 11.02 %. The 18O and 2H values of well and spring waters are linearly correlated, in a similar manner to the World Meteoric Water Line (WMWL). The 14C datings indicate that the age of groundwater obtained using different models ranges between 2495 and 10,696 years.