Evaluation of the groundwater quality status using water quality indices in and around Hawassa City, Southern Ethiopia

Abstract

This study looked into the quality of groundwater in Hawassa City and its periphery as a baseline survey for the ‘Assessment of Feasibility of Managed Aquifer Recharge’. Water quality was assessed using four water quality indices. Weighted arithmetic Water Quality Index (WA-WQI), Synthetic Pollution Index (SPI), and Entropy Weighted Water Quality Index (EWQI) were used for domestic water quality assessment. Whereas, Overall Irrigation Water Quality Index (IWQ), was used for irrigation water quality assessment. Accordingly, WA-WQI results showed that 6.25 and 93.75% of the water samples were very poor and poor quality status, respectively, making them unsafe for consumption. However, according to SPI, every water sample was unsuitable for usage as potable water. According to the EWQI model, the water quality status of 22.92, 58.33, and 18.75% of the water samples was average, poor, and extremely poor, respectively. Of the three models used for assessing water quality, SPI is the robust. The primary parameters in both models used to estimate the water quality statuses (68–89%) were F^–, K⁺, BOD₅, COD, and HCO₃^–. The Overall IWQ score indicated fair and moderate water quality levels (6.25 and 93.75%), respectively. Sodicity and toxicity hazard classes shared (47–80%) in determining the irrigation water quality status. This result indicates that the aquifer of the city is being contaminated. This requires enforcing strict standards in septic tank construction. Additionally, increasing groundwater recharge from precipitation sources during the rainy seasons to further dilute the concentration and increase aquifer volume is required.

Keywords:

• Water quality index
• synthetic pollution index
• irrigation water quality index
• sodicity
• toxicity

REVIEWING EDITOR:

• Sanjay Kumar Shukla
• Edith Cowan University
• Australia

SUBJECTS:

• Agriculture & Environmental Sciences
• Environmental Studies
• Environment & Resources
• Environment & Health
• Ecology Environment Studies
• Environment & the City
• Civil, Environmental and Geotechnical Engineering

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Getahun Alemu

Getahun Alemu is a lecturer in the water resources and irrigation department, Hawassa University. Currently a PhD student working on water quality and ground water artificial recharge management in the southern Ethiopia.

Awdenegest Moges

Awdenegest Moges (PhD) is an Associate Professor in the department of Biosystems Engineering, Hawassa University Ethiopia. His research interest is in soil and water management. Published articles related to soil, water and conservation, landuse dynamics and environmental management aspects.

Sirak Tekleab

Sirak Tekleab (PhD) is an Assistant Professor in Addis Abeba University, Ethiopian Institute of Water Resources. His research works focused on hydrological processes and modelling, land use land cover and climate change impacts on stream flows and water resources. His research interest includes hydrological processes understanding, modelling, isotope hydrology for water resources management, and investigation of water availability under environmental changes.