REGIONAL ESTIMATION OF SNOW WATER EQUIVALENT IN THE ITALIAN ALPS USING KRIGING

Spatial estimation of Snow Water Equivalent at snowmelt is tackled using kriging from a sparse network of 34 snow stakes within the central Italian alps and pre-alps, for the period 1985-2005. First, sparse snow density pits first are used to find a relation between snow density, geomorphologic features and the season. Then, density estimates are used to evaluate SWE at snow stakes. To highlight regional features in SWE distribution, a Principal Components Analysis (PCA) is carried out, resulting into partition of the investigated area in two different homogeneous regions featuring different SWE statistics, consistent with previous findings. Then, the covariance of the SWE field within the two regions is studied, necessary for kriging, and its regularization provided based upon geomorphic attributes. Then, a Kriging procedure based upon the so obtained covariance fields is developed and cross-validated. Kriged SWE maps are then illustrated for two sample years, to demonstrate use of the method. The procedure provides well estimated, least variance SWE values and it is relatively simple and fast because it uses only information upon altitude at the investigated sites. Therefore, it can be used for spatial estimation of SWE within the investigated region for hydrological conjectures.