THERMAL RESPONSE TO CHANGING FLOOD CONDITIONS IN LOW-LYING AREAS

Flooding of the Rock River in southeastern Wisconsin has increased in frequency and duration over the past 10-15 years. This flooding is especially problematic in rural, agricultural areas, impacting the regional environment and economy. Farmers and residents have lost access to their property and fields, road closures are increasingly common, and land has been reassessed to reflect increasing inundation areas. Particularly for the Rock River in Dodge County, blame for flooding is likely due to poorly coordinated stream management. However, natural drivers such as climate change cannot be discounted. With no expectation of a change in stream management or reversal of climate trends, quantification of long term impacts of high water levels on the riparian system and human activities must be undertaken. Research suggests that high water events are having significant impacts on ecosystems and stream health. Using temperature as a proxy for system response and especially groundwater/surface water interaction, we propose the Rock River flooding has increased exchange with the subsurface. Flood stage enhances influent conditions into the riparian system and proximal wetlands. Warmer surface waters drain into the wetlands during spring floods and flush out as flooding subsides. In warm summer months, this can have an especially negative influence on the riparian corridor, reducing buffering effects of groundwater on stream temperatures.