Snowpack depth modelling and water availability from LIDAR measurements in eastern Pyrenees

In order to evaluate water reserves in mountain watersheds the Institut Geologic de Catalunya (IGC) jointly with Institut Cartografic de Catalunya (ICC) have begun a project to model snowpack depth distribution at the study site of Vall de Nuria (38 Km 2 basin located in eastern Pyrenees). Remote sensing airborne LIDAR (Light Detection and Ranging) survey and field work validations were performed to make this calculation. Modelling snowpack distribution is a complex task because of its spatial variability. Despite being a recently developed technique, LIDAR has become a useful method in snow sciences because it has the advantage to offer dense point data and to cover wide areas with little economic and field work effort. The new methodology presented combines LIDAR data with field work, the use of Geographical Information Systems (GIS) and the stepwise regression tree (SRT), as extrapolation technique has allowed us to map snowpack depth distribution with high spatial resolution. Extrapolation is necessary because raw LIDAR data is only obtained from part of the study area in order to make the technique as affordable as possible. Promising results show low differences of total snow volume calculated from modeled snowpack distribution and total snow volume from LIDAR data only differ 1.4%.