Hydrogeochemistry and groundwater quality assessment along Wadi Al Showat, Khamis Mushiet District, Southwest Saudi Arabia

Abstract:

In the present study, the hydrochemistry and geologic characteristics of the shallow groundwater aquifer along Wadi Al Showat, Khamis Mushiet District, Southwest Saudi Arabia was evaluated and assessed. Along this wadi the fractured/weathered basement rocks house significant quantity of groundwater that usually used by local people for agricultural and domestic purposes. Assessing and evaluation of the quality of the groundwater in such shallow aquifers is very important; especially the groundwater is generally occurred within the fractured basement rocks at shallow depths, thus exposing the groundwater to surface or near-surface contaminants is expected. For this purpose hydrochemical and biological analysis was conducted for 25 water samples collected from the available shallow dug wells along the studied wadi. The study reveals that the groundwater quality changed due to the agriculture and urbanization practices along the wadi. The effect of domestic waste water and septic tanks was obvious.

In addition, the field investigation indicates that the basement rocks in the area is dissected by two main sets of fractures that oriented in the west-northwest and east-west directions. In some places, the basement rocks is intruded by coarse-grained, quartz-rich quartzite grained monzogranite, and pegmatite veins that have a coarse-grained weathering product, therefore, they tend to develop and preserve open joint systems between the granitic blocks. These fracturing system are important from the hydrogeological point of view, as they facilitate the storage, water flow movement through them and also facilitate the vertical infiltration of the surface pollutants. These results led to a better understanding of the groundwater characteristics that is important in groundwater management in the study area.