INVITED FACULTY TALK - The “Teflon Basin” Myth Debunked: Most Snowmelt Runoff Is “Old” Water And Not “New” Water
Williams, Mark W 1
1 INSTAAR and Geography
New research shows high-altitude aquifers honeycomb parts of the Colorado Rockies, trapping snowmelt and debunking the myth that high mountain valleys act as “Teflon basins” to rush water downstream. In much of western North America, snow and snow melt provides the primary means for storage of winter precipitation, effectively transferring water from the relatively wet winter season to the typically dry summers. A common assumption is that high-elevation catchments in the western United States behave like "Teflon basins" and that water released from seasonal storage in snow packs flows directly into streams with little or no interaction with geologic or biologic materials.
We determined source waters and flowpaths in the Green Lakes valley of the Front Range using isotopic, geochemical, and hydrometric data in 2- and 3- component hydrograph separations along with end-member mixing analysis (EMMA). EMMA results showed that much of the water released from the seasonal snowpack infiltrated into subsurface reservoirs and that old groundwater contributed almost 50% of flow on the rising limb of the hydrograph and 80% on the recession limb. Thus most of the water sampled from North Boulder Creek during the runoff months was “old groundwater” that had been stored in subterranean mountain catchments.
The common perception that water stored in mountain snow packs runs immediately into streams and rivers is probably wrong, and the Teflon basin myth is incorrect.