Groundwater Salinity: Applying the Specific Conductance and Water Type Proxy

Area of Science:

• Earth Science
• Environmental Science
• Hydrogeology

Background:

• Groundwater is vital for water supplies, but salinity can limit its use.
• Total dissolved solids (TDS) is a key measure of salinity, often estimated using specific conductance (SC).
• Existing TDS-SC proxies are inaccurate for groundwater due to non-linear relationships and varying major-ion composition.

Purpose of the Study:

• To develop and validate new proxy methods for estimating groundwater TDS and salinity.
• To improve the accuracy of salinity assessments in groundwater resources.

Main Methods:

• Developed nonlinear log-log proxy relationships using SC and five major-ion groundwater types.
• Utilized a large dataset of 149,059 discrete groundwater samples for proxy development.
• Validated proxies against discrete TDS and salinity measurements.

Main Results:

• The new groundwater proxies provide accurate TDS and salinity estimates (median percent difference <±0.8%).
• Proxies are effective across a wide SC range (up to 200 mS/cm).
• The method is rapid, cost-effective, and suitable for on-site measurements.

Conclusions:

• The developed proxies offer a significant improvement for estimating groundwater salinity compared to traditional methods.
• These tools enhance the utility of groundwater resources by enabling more reliable salinity assessments.
• The method supports better management and utilization of groundwater supplies globally.