As Wisconsin’s climate changes over the coming decades, the hydrology of its landscapes will almost certainly change along with it. In turn, changes will occur in streamflows, lake levels, and wetland extent and in the ecosystems that depend on them. Many questions abound: Will present day trout streams remain as trout streams? Will lake levels rise or fall?
The WICCI Central Sands Hydrology and Aquatic Ecology workgroup aims to frame potential aquatic resource issues and explore their dependencies on a changing climate.
The Central Sands of Wisconsin is a loosely defined region characterized by coarse soils, outwash plains, and terminal moraine complexes associated with the Wisconsin Glaciation. For purposes of this working group, the region of interest is bounded on the west by the Wisconsin River and to the east by the downstream ends of headwater streams in the Fox-Wolf Watershed.
This region is home to many prized aquatic resources (80+ lakes > 5 ha, > 1000 km of headwater streams, and wetlands), forests, and profitable agriculture. Aquatic resources here are fed by groundwater which is recharged by precipitation on the overlying landscape. Consequently the landscape hydrology, groundwater, and aquatic resources are intimately connected.
While climate change would be expected to alter the landscape hydrology under any land cover, the landscape hydrology here is unusual in that it has already been greatly altered by irrigated agriculture, which now covers some 200,000 acres. This agricultural system, expanding now for over 50 years, pumps groundwater for irrigating the otherwise droughty sandy soils. Thus a potential tension exists between the health of groundwater-fed aquatic resources and the groundwater-consumptive agriculture.
Studies performed in the 1960s and 1970s suggest that the net effect of irrigation is to reduce net groundwater recharge amounts by about 10-25% on irrigated lands compared to nonirrigated lands (improved estimates are being produced by Lowery and Bland at the University of Wisconsin Department of Soil Science). Apparent stresses have on the region’s lakes and streams may include the drying of Long Lake near Plainfield and the Little Plover River.
This working group has developed conceptual models of how anticipated climate change may induce changes in hydrology of the nonirrigated and irrigated landscape. Next steps will be to develop quantitative models, run “what-if” scenarios, assess how climate change may perturb the landscape’s hydrology system and how aquatic resources might be affected. We anticipate being able to predict which resources are likely to be more resilient and which are likely to be more fragile. Finally, we hope to recommend policies and strategies for maintaining or dispensing threatened resources.
Please contact George Kraft if you have any comments or concerns regarding how climate will affect the hydrology of Wisconsin's Central Sands.