CAVECHAMP – A MODEL FOR THE EVOLUTION OF CAVE PASSAGE CROSS-SECTIONS AND LONGITUDINAL PROFILES

Caves record substantial information about the conditions during their development through the morphology of their passages, providing clues to both the process of speleogenesis and the paleohydrological conditions during former stages of cave development. To better understand the controls of cave passage morphologies, we have developed a physically based model for the evolution of cave passage cross-sectional shape, which erodes cave walls based on a power-law of local wall shear stress. The model includes a flow solver that can simulate flow along an extended conduit, including the effects of backwater hydraulics. We also simulate ventilation of the air-filled portion of the conduit via the chimney effect and explore its influence on carbon dioxide dynamics and cave passage evolution. We show that CO₂ exchange between air and water can produce knickpoints within the cave channel. Keyhole-shaped cave passages are quite common in nature. Here, we examine the variety of mechanisms by which they can form, including changes in flow, tectonic forcing, and chemistry and explore whether these mechanisms might be distinguishable in the field.