Groundwater Resources in Muthanna Governorate, South of Iraq

Abstract

Muthanna Governorate, located in southern Iraq, is the second-largest governorate in the country by area. The unconfined aquifer was studied by identifying the geological formations that form this aquifer. This research aims to use stratigraphic succession to establish geological correlations and identify formations that serve as groundwater aquifers. It also aims to identify and isolate the geological formations comprising the unconfined aquifer, as well as to assess its hydrogeological characteristics and groundwater hydrochemical properties. Geological maps of Muthanna Governorate and data from deep wells as well as fifty-nine drilled wells in the study area were used to prepare a series of geological sections. These sections provide valuable insights into the areas of each geological formation that contribute to the unconfined aquifer. Five main zones were identified, where the unconfined aquifer was sometimes considered an isolated geological formation (e.g., the Umm Er-Radhuma or Dammam formations) and sometimes consisted of a succession of two formations (e.g., the Euphrates and Dammam formations, or the Dammam and Umm Er-Radhuma formations). The results showed that the average hydraulic parameters—namely, thickness, total depth, transmissivity, and water table—were 68.7 meters, 151.5 meters, 133 m²/day, and 162.6 meters above sea level, respectively. The groundwater salinity distribution map indicated several locations with high salinity values, which are attributed to the different lithologies forming the aquifer as well as the varied environmental depositional conditions of the geological formations that compose it. Additionally, the groundwater moves continuously from recharge areas toward discharge areas in three directions. Two primary salinity types were identified: calcium sulphate and sodium sulphate. The salinity, reflected by cation and anion concentrations, caused groundwater contamination in some areas of Muthanna's unconfined aquifer due to increasing concentrations. Consequently, five groundwater samples were suitable for human consumption, nine were appropriate for agricultural use, and forty-nine were suitable for animal use.