Hydrometeorological factors determining the development of water table cave patterns in high alpine zones. The Ordesa and Monte Perdido National Park, NE Spain

Abstract

This study is focussed on the geomorphological characterization and the processes driving the evolution of the highest karst system in Western Europe, which is located in the Ordesa and Monte Perdido National Park (PNOMP), in the central-southern Pyrenees. The karst system does not seem to have a well-developed epikarst. The studied area shows a karst network of polygenic branchwork type in the vadose zone. Additionally, the explored karst conduits in the epiphreatic zone show a water table cave pattern that is different to the looping one, which is the expected cave pattern development for a karst located in a mountain zone where a high irregular recharge is expected. We have designed a conceptual recharge model through a multidisciplinary approach, which has included the making of a new detailed geological and hydrogeological map of the study area, morphometric analysis of cavities, tests with fluorescent dye tracers and hydrometeorological monitoring of the karst system associated with the Garcés Spring. This spring, together with the Font Blanca Spring, constitutes the main water discharge point of the hydrogeological system. The conceptual recharge model explains how the observed unexpected cave pattern has developed in this karst.