In this study, lateral groundwater inflow was examined, according to the phenomena of groundwater mixing, groundwater flow and groundwater chemistry. The study region is composed of different aquifer systems; including karst-fracture media (Rattga-Jeed carbonates aquifer), fissure–porous media (Mullusi, Mullusi-Ubaid, Hartha-Rutba, and Digma-Tayarat aquifers) and porous media (Permo-carboniferous clastics rocks of Ga’ra aquifer).The aquifers are vertically super-imposed or of lateral contacts make open hydraulic connection between aquifers system. There is a severe shortage of water resources in the region because of rare precipitation and strong evapotranspiration. These conditions have hampered eco-environmental improvement. The aquifers should be considered as important water reserves for industrial use in mineral exploration and exploitation, as well agricultural purposes. The monitoring of groundwater quality network consist chemical variables (major ions concentration) and groundwater levels in sixty four water wells. The study describes the phenomena of lateral groundwater inflow (hydraulic connection) among aquifers systems using hydrogeologic phenomena compiled with the application of hydrochemical characterization on Piper Trilinear Plot. The results are supported and also benefit in studying the rational development of groundwater resources, which will significantly interpret the difference between supply and demand of groundwater, where the lateral groundwater recharge is a key factor in water balance studies, especially in semi-arid areas. Four mixing phenomena detected by Piper Trilinear Plot proved the existence of four trends of lateral groundwater flow interconnections within the hydrogeologic system. Accordingly, Al-Hamad complex hydrogeologic system can be classified into four subsystems, Mullusi-Ga’ra and Digma-Tayarat subsystem, Mullusi-Jeed and Rattga-Jeed subsystem, Mullusi-Rutba and Muhaywir-Ubaid subsystem, Mullusi and Mullusi-Ubaid subsystem.