Natural and anthropogenic controls of groundwater salinity in Michigan

Session: 53. - Great Lakes Water Level Fluctuations and Water Management

Zachary Curtis, Michigan State University, [email protected]
Huasheng Liao, Michigan State University, [email protected]
Shu-Guang Li, Michigan State University, [email protected]

Abstract

Michigan - although surrounded by Great Lakes – relies heavily on groundwater to support its different water-use sectors. There is, however, growing concern over the sustainability Michigan’s groundwater resources due to reports of elevated salinity in shallow aquifers across the state. To better understand the sources, controls, and dynamics of groundwater salinity in Michigan, we performed a systematic, statewide investigation of near-surface conditions across multiple scales (both in space and time). In particular, we combined 1) data-driven modeling of massive amounts of statewide groundwater/geologic information across multiple spatial scales with 2) detailed field sampling, historical data mining, and process-based modeling for important local systems.  The results show that a large-scale natural process is primarily responsible for the salinization, namely, the upwelling of deep brines into low-lying groundwater discharge areas.  At local scales, the relative impact of upwelling is controlled by: i) streams and rivers – which act as ‘natural pumps’ that bring deeper groundwater to the surface; ii) the occurrence of nearly impervious geologic material at the surface – which restricts freshwater flushing of deeper groundwater; and iii) the space-time evolution of water well withdrawals – which, over time, induces migration of saline groundwater from its natural course.

1. Keyword
geochemistry

2. Keyword
computer models

3. Keyword
distribution patterns

4. Additional Keyword
groundwater salinity

5. Additional Keyword
groundwater pumping