Measuring flow rates and characterizing flow regimes in hot springs

Mathon, B.; Schoonen, M.; Borda, M.

Detailed studies were conducted at Big Boiler hot spring in Lassen Volcanic National Park, CA, and Ojo Caliente hot spring in Yellowstone National Park, WY, to measure the flow rate and characterize the flow regime of hot spring drainages. These drainages represent some of the most dynamic interfaces between the hydrosphere and atmosphere with steep temperature gradients and chemical gradients. The rate of thermal disequilibrium and chemical disequilibrium dissipation depends on the flow rate and flow regime. The drainage of each hot spring was divided into ten or more segments and water samples were collected at segment boundaries. Fluid flow velocity throughout the drainage was measured using an in situ flow probe where possible and by determining the advancement of a red food dye tracer through the flow channel. A combination of field and laboratory studies was used to adapt a method based on the transport-controlled dissolution rate of gypsum to characterize the flow regime throughout the drainages. Laboratory experiments as a well as a deployment in an artificial drainage were conducted to validate the application of this method for hot spring environments. The deployment of the gypsum tablets was complemented by using digital videography to record the nature of the flow regime throughout the drainages.