welshkate

I currently work in climate research, determining CO2 concentrations in polar ice. As part of that process I spend a few hours a day working in a freezer at -25 degrees Celsius. One thing I do to help combat the cold (along with all the layers I wear) is to drink as much water as possible, a few hours prior to going in the freezer. 

Courtesy photo (Eric Cravens): Me at USGS National Ice Core Lab, Denver, CO

Dry, cold air causes the body to lose water at a greatly accelerated rate. Breathing through the mouth during exercise under such conditions speeds up the dehydration process through exposure of moisture reserves in mucous membranes to this super dry air. Additionally, the body sends as much blood as possible to the core to provide insulation. This can become a critical if dehydrated because the thickened blood won’t reach to the constricted capillaries of the extremities potentially leading to hypothermia. I guess, what I’m trying to say is that if you suffer from cold on the river, in addition to your usual measures of staying warm, try drinking more water, it may help.