Impact of rapid urbanization and tourism on the groundwater quality in Al Madinah city, Saudi Arabia: a monitoring and modeling approach

The urbanization process in Al Madinah city developed with high irrigation and network watering systems, which have firmly entered the aquifer system. Optimization of the potentiometric surface (PS) is a major problem and is recovered by dewatering. In this study, twenty-three groundwater samples were collected from different locations of Al Madinah in the year 2011 to determine hydrogeochemical processes and potential sources of important physicochemical parameters. Multivariate statistical methods and AquaChem techniques were used to evaluate groundwater parameters. The confined aquifer consists of basaltic lavas and sub-basaltic alluvial deposits. The lowest value of total dissolved solids (TDS) concentrations may be associated with the highest nitrate (NO32-) content and high biological oxygen demand (BOD5) values, which could be the result of sewage from anthropogenic sources such as industrial and septic tanks. Leaching and dissolution of rocks through weathering (geomedia or sediment dissolution) and groundwater flow also led to groundwater degradation. Groundwater samples were divided into two clusters, cluster I consists of 3 samples (group 1) while cluster II consists of 17 samples (groups 2 & 3). In groups 1, 2, and 3, turbidity, electrical conductivity, TDS, dissolved oxygen, NO32-, sulfate, chloride, potassium, sodium, silica, BOD5, and sodium adsorption ratio were significantly different (sig. < 0.05), whereas pH, temperature, PS, bicarbonate, and calcium were not significantly different (sig. > 0.05). Factor analysis is divided into six factors: evaporation, geomedia dissolution, anthropogenic, agriculture, PS, and recharge. Groundwater samples were unsaturated in terms of gypsum, anhydrite, and quartz.