32 Hydrogeology
Added due to amount of discipline abstracts submitted.
Tuesday, 10 March 2026
1:30 PM - 5:30 PM
RCC, 106
Decadal Groundwater Temperature Increase in the Upper Midwest: Long-term and High-resolution Monitoring in a Baseflow-dominated Watershed, Manistee National Forest, Michigan
Paper number: 32-10
Program: Technical Sessions
Time: 4:00 PM – 4:15 PM
Authors
Abstract
The unconfined aquifer system underlying the Pines Point Semi-Primitive Area of Manistee National Forest in Michigan supports a dynamic, linked groundwater-surface water system along the White River, a Michigan State Natural River and candidate Federal Wild and Scenic River. The White River is an important local, regional, and national aquatic and recreational resource. A monitoring well network, installed in the thick sequence of well-sorted, medium-grained outwash sand, was instrumented in advance of Savanna Ecosystem restoration efforts that began in 2011 to collect high-resolution (hourly) groundwater levels and temperatures throughout planned landscape alterations by the US Forest Service. Those resource management activities have continued until very recent cutbacks to USFS efforts. Long-term data indicate groundwater temperatures in this important critical zone system are responding, significantly, to climate-change induced trends in monthly and annual precipitation and air temperatures.
Groundwater temperatures have increased significantly in this baseflow dominated watershed. Changes in air temperatures, along with seasonal changes in precipitation and to snowmelt patterns, appear to be the driver of meaured increases in groundwater temperatures on the scale of +0.6 deg C over the last 10 to 15 years. This increase in groundwater heat content is transferred directly and rapidly to surface water through the highly permeable aquifer sediments that host the White River and other, regional, baseflow-dominated streams. These high-resolution groundwater temperature data are now being used to calibrate a coupled surface and groundwater model to simulate heat transport from rainfall through groundwater discharge. The implications for aquatic resource management of cold-water fisheries are significant. Higher groundwater discharge temperatures will increase surface water temperatures and lead to increased stress and mortality for resident trout and salmon species. In Michigan, the economic impact of recreational fishing is ≈ $2 billion/year.
Geological Society of America Abstracts with Programs. Vol. 58, No. 1
doi: 10.1130/abs/2026SE-411890
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