Hydrochemical assessment of groundwater from shallow aquifers in parts of Wadi Al Hamad, Madinah, Saudi Arabia

• Published in: Arabian journal of geosciences 2017, Vol.10 (2), p.1-15, Article 35
• Main Authors: Alharbi, Obaid Aziz, Loni, Oumar Allafouza, Zaidi, Faisal K.
• Format: Article
• Language: English
• Subjects: Agrochemicals; Alluvial deposits; Alluvium; Aquifers; Aragonite; Area; Aridity; Calcite; Data processing; Dissolved solids; Dolomite; Dolostone; Drinking water; Earth and Environmental Science; Earth science; Earth Sciences; Evaporation; Extreme values; Farming; Farms; Fertilizers; Fluorides; Groundwater; Groundwater chemistry; Groundwater quality; Ion exchange; Organic chemistry; Original Paper; Principal components analysis; Quaternary; Sedimentary facies; Silicates; Trace elements; Unconfined aquifers; Water analysis; Water quality; Water quality standards; Water sampling; Weathering
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-016-2805-z

The present study was carried out in the Mulaylih area which forms a part of Wadi Al Hamad in the Madinah Province of Saudi Arabia. Thirty groundwater samples from agricultural farms were collected and analyzed for various physio-chemical parameters including trace elements. The area is occupied by the Quaternary alluvium deposits which form shallow unconfined aquifers. Evaporation and ion exchange are the major processes which control the major ion chemistry of the area. The extreme aridity has results in high total dissolved solid values (average of 9793.47 mg/l). Trace element concentrations are low and are mainly attributed to geogenic sources (silicate weathering). Na-Cl groundwater type is the main hydrochemical facies found in the area. The waters are found to be oversaturated with calcite/aragonite and dolomite. The average nitrate concentration was found to be 134.10 mg/l and is much higher than the WHO recommended limit of 50 mg/l in drinking water. Their high values are mainly associated with the application of N-fertilizers on the agricultural farms. The average fluoride concentration in the study was found to be 1.54 mg/l. The relation between F and Cl and Cl and Na reveals that the fluoride concentrations are mainly attributed to geogenic sources. A comparison of the groundwater quality with the Saudi drinking water standards shows that the water is unfit for drinking. The high salinity and sodicity of the groundwater make it unfit for irrigation. Principal component analysis resulted in extraction of four principal components accounting for 79.5% of the total data variability and supports the fact that the natural hydrochemical processes (evaporation and ion exchange) control the overall groundwater chemistry.