Utilizing Geophysical and Hydrogeological Techniques for Developing De-Salinization Water Supplies, Cabo San Lucas, Mexico

Potable freshwater supplies in the southern portion of the Baja Peninsula are limited.  As a result, the Comision Nacional de Agua (CNA) or National Water Commission strongly encourages using de-salinization wherever possible, especially for non-municipal and non-potable water supplies.  In Cabo San Lucas and San Jose Del, developing high capacity de-salinization water supplies can be challenging.  The saturated thickness, composition, and lateral extent of the unconsolidated formation along the Pacific Ocean and Sea of Cortez is highly variable, which can significantly impact well yields.  In addition, the presence of a Federal Zone (adjacent to the Pacific Ocean and Sea of Cortez) results in the placement of de-salinization wells further from the water bodies, which can limit the overall hydraulic inter-connection and also reduce well yields. 

We successfully used geophysical surveys (electrical resistivity imaging), exploratory test drilling, aquifer tests and ground-water flow modeling to design the raw water supply for de-salinization plants on several properties.  The ERI surveys were able to identify subsurface zones that are electrically conductive (saturated with saline water) and have sufficient saturated thickness within the unconsolidated beach aquifer to sustain high capacity well yields.  In addition, we have also conducted exploratory test drilling, test well, and aquifer pumping test programs and have utilized digital ground-water flow models in order to design de-salinization production wellfields that maximize yield and minimize the potential for capturing potable fresh water (which is not allowed by the CNA).  Results from several case studies for developing high capacity de-salinization water supplies conducted in the Cabo San Lucas area will be included in the presentation.