This seminar is part of the Tuesday Seminar Series organized by the Center for Hydrogeology and Geothermics (CHYN) at the University of Neuchâtel. We are pleased to welcome Dr. Tanguy Racine from the University of Neuchâtel (UNINE), who will discuss innovative approaches to charachterize geometric informtion of karst conduits. 

Abstract 

Karst landscapes are characterised by dissolution landforms, including cave conduit networks along which meteoric waters flow. Two main geometric parameters, namely hydraulic diameter and relative roughness control head losses and flow in a karst conduit. The former can be roughly estimated from the topometric data of traditional cave surveys, while the latter is usually sampled from a range of plausible values to fit the observed hydraulic signals. Detailed cave geometry, in the form of a dense 3D point cloud allows for more complex geometric descriptors and their spatial correlations to be computed, and their impact on hydraulic response to flow conditions to be tested.

We collected field data by mapping the caves passages of interest with a dynamic laser scanner in various, hydrologically active European caves. We modelled the cave walls as triangulated meshes using a Poisson reconstruction and developed strategies to automatically extract a cave centerline based on the point cloud geometry. We devised an algorithm to find optimal section orientations and compute sequential mesh-plane intersections. Using this newly assembled pipeline for dense point clous geometric description, we highlight the value of generating new morphometric indicators adapted to the complexity of cave datasets to inform models of flow and transport at cave-network scale.