Characterization of groundwater in Quaternary aquifer of the Yanbu Al-Nakhl Basin, Al-Madinah Al-Munawarah Province using pumping tests and hydrochemical techniques

Abstract

In the Yanbu Al-Nakhl Basin, Quaternary aquifer is the main source of groundwater supply for different uses. The groundwater wells that have been drilled in this area are now not subject to local government regulation in terms ofdistances and daily pumping rates. This may lead to declines in groundwater levels and deterioration of its quality. The primary goal of this research is to characterize the Quaternary aquifer using measurements of hydraulic parameters and groundwater quality. To achieve this purpose, all aquifer parameters such as thickness, lithology, depth to water, water table, well loss, formation loss, well efficiency, transmissivity and hydraulic conductivity were measured. Moreover, chemical analysis for major ions as well as minor and trace elements of 14 samples were carried out to determine the physicochemical properties, groundwater facies, controlling mechanisms and five irrigation water quality indices (IWQIs). The results revealed that, groundwater originates mainly from highly permeable Quaternary alluvial sediments of (60 m thickness), and flows generally from north to south. The calculated hydraulic parameters indicated that, the average of well efficiency(γ) ranges from 42.21% to 72.2%, transmissivity (T) varies between 88.2 and 105.4 m2/day, and hydraulic conductivity (K in m/day) ranges from 4.41 to 9.3. In hydrochemical point of view, there are various types for groundwater in the study area including Ca - HCO3, Na - Cl, mixed Ca – Mg – Cl - SO4, and Na – Ca - HCO3. The processes of evaporation and rock – groundwater interaction were significantly influenced the groundwater quality in the Wadi. The computed IWQIs (TDS, TH, SAR, PS, MH, and RSC) had mean values of 1537.685, 678.31, 3.940625, 2.140625, 25.85687 and −10.8068 respectively, indicated that no restriction range for agriculture uses characterizes the majority of groundwater in Wadi Yanbu Al-Nakhl basin.