Spatial modeling of the water table and its historical variations in Northeastern Italy via a geostatistical approach

Abstract

Groundwater resources are the most important freshwater source for any human use and its preservation in the context of climatic variability is of crucial importance. So far, no systematic spatial estimation of the water table in Northeastern Italy has ever been made available, whereas the Veneto Region (North-Eastern Italy) provides a free database with recorded water table measurements between 1999 and 2022. These starting data have been cleaned, leading to a final database of 53 yearly water table data. The lack of knowledge about the spatial estimation of the water table within the historical period is overcome through the well-known geostatistical technique of cokriging. The latter is the most suitable approach for reproducing water table elevations upon local terrain elevation as an auxiliary variable. Results underline modest decrements between 1999 and 2022, which are more pronounced in the Prealps area and in general in sedimentary soils, and less in the Fontanili belt, a crucial freshwater source area. Moreover, the estimated water table change is highly non-linear in time from year to year and highly varying in space. The results seem particularly interesting in the plain areas and within the Fontanili belt, where the management of groundwater resources is becoming crucial. However, the spatial estimation in the Prealps area needs to be improved for a better assessment and future reliable predictions.