Groundwater availability as constrained by hydrogeology and environmental flows

Area of Science:

• Environmental Science
• Hydrogeology
• Ecology

Background:

• Groundwater pumping can reduce streamflow, impacting aquatic ecosystems.
• The Great Lakes-St. Lawrence River Basin Water Resources Compact mandates measures against adverse ecosystem impacts from water withdrawals.
• Understanding groundwater-stream interactions is crucial for sustainable water management in the region.

Purpose of the Study:

• To explore hydrogeologic and environmental flow constraints on groundwater availability in the Great Lakes Basin.
• To develop a methodology for calculating maximum allowable groundwater pumping rates.
• To identify key factors influencing streamflow depletion due to groundwater extraction.

Main Methods:

• Developing a methodology to calculate maximum allowable pumping rates.
• Analyzing hydrogeologic and environmental flow limitations across local and regional scales.
• Investigating the sensitivity of results to factors like pumping duration, hydrogeology, streambed conductance, and streamflow depletion limits.

Main Results:

• Groundwater availability in the Great Lakes Basin is constrained by a combination of factors.
• Hydrogeologic yield and environmental flow limitations vary significantly across the basin.
• Pumping time, local/regional hydrogeology, streambed conductance, and streamflow depletion limits influence potential streamflow depletions.

Conclusions:

• Groundwater availability is limited by both physical hydrogeology and ecological flow requirements.
• A methodology for calculating sustainable pumping rates is essential for water resource management.
• Identifying influential hydrogeologic and spatial variables is key to mitigating streamflow depletions and informing policy.