Assessing groundwater salinity across Africa.

Area of Science:

• Hydrogeology
• Environmental Science
• Water Resource Management

Background:

• Groundwater is Africa's primary drinking water source and vital for irrigation.
• Groundwater salinity is a key limitation for water resource development, with limited quantitative data in Africa.
• Understanding groundwater salinity is crucial for water security and agricultural productivity across the continent.

Purpose of the Study:

• To analyze the extent of groundwater salinization across Africa.
• To identify geological and climatic factors associated with high groundwater salinity.
• To investigate the natural and anthropogenic drivers of groundwater salinization.

Main Methods:

• Compilation and analysis of a large dataset (n=12,255) of groundwater salinity (electrical conductivity) from across Africa.
• Statistical analysis of salinity data in relation to geological and climatic contexts.
• Review of existing case studies on groundwater salinization causes.

Main Results:

• Approximately 80% of analyzed groundwater samples have electrical conductivity below 2000 μS/cm, indicating suitability for many uses.
• High salinity levels (>2000 μS/cm) are geographically restricted to specific geological and climatic environments.
• Groundwater salinity does not broadly impact water security but exacerbates issues in arid, low-recharge areas.

Conclusions:

• Groundwater salinity is a manageable issue for most of Africa, but critical in specific arid environments.
• Anthropogenic activities (irrigation, pumping, water transfers) significantly influence groundwater salinity.
• Salinization drivers include human activities, climate change, rock dissolution, and saltwater intrusion, necessitating integrated management strategies.