New Proxy-based Hydrological Reconstructions over the Past Five Centuries in Southwest Wisconsin

Effective water resource management for the present and future requires a long-term temporal perspective on the variability of past water resources. Instrumental records are insufficient to provide insight into the occurrence of rare, severe events that have caused pronounced economic, ecological, and social implications over longer time scales. This is problematic in light of numerous predictions that future extreme events will become more frequent and intense due to climate change. Wisconsin benefits from abundant water resources, yet droughts that occurred during the last century illustrate that we are vulnerable to extreme events. The influence of extreme drought has significant implications for the ecology and economy of our state, both of which are intimately connected to the natural environment. The purpose of this proposed research is to (1) improve understanding of the effects of environmental conditions and variability on groundwater levels; (2) inform groundwater management strategies for long-term management targets that consider extreme weather events and climatic trends; and (3) demonstrate through our results the implications of changing environmental conditions on groundwater management for southwest Wisconsin. To achieve these goals, we propose a new and deeper analysis of oak tree-ring samples previously collected in southwest Wisconsin which will sharpen the temporal window of climate response identified in tree growth and provide sub-annual records of seasonal groundwater variability. We will then combine those data with multiple, newly developed, 500+ year tree-ring chronologies from eastern redcedar (Juniperus virginiana) trees growing throughout the Driftless Area of southwest Wisconsin to reconstruct multi-century records of depth-to-groundwater on local to regional scales for southwest Wisconsin; identify the frequency, spatial extent, and severity of past extreme hydrologic events; and, enhance the availability of data that are used to calibrate existing hydrologic models and refine predictions of the effects of future climate change on the agricultural and ecological systems of Wisconsin.