The influence of groundwater flow on thermal regimes in mountainous terrain: A model study

Abstract

Groundwater flow in high‐relief mountainous terrain is modeled to examine how geology, surface topography, climate, and regional heat flow influence the pattern and magnitude of an advective thermal disturbance. A numerical procedure is used to estimate the position of the water table within constraints provided by the available infiltration rate and the permeability of the mountain massif. Results show that where the water table is located at depth within the mountain massif, the rate of groundwater recharge, rather than permeability, is the appropriate factor to characterize the potential for an advective disturbance. Thermal disturbances should be assessed within the framework of the two‐dimensional character of the flow system because interpretations based on one‐dimensional models are prone to significant error. Modeling of site‐specific systems can exploit the existence of a permeability “window,” where temperatures in discharge areas and in springs discharging from fracture zones reach peak values. Temperatures of thermal springs reflect the complex interaction between flow within the mountain massif and flow through permeable fracture zones. Consequently, simple calculations relating the geothermal gradient, depth of maximum groundwater circulation, and discharge temperature improperly represent the physics of the process.