Insights on vadose zone hydrologeology within a carbonate setting : preliminary results based on a new vadose zone monitoring system

Abstract

A new monitoring network was setup to adequatly assess the hydryogelogical condtions within the vadose zone in Malta. The installation of the monitoring equipment allows for the measurement of water content along the vadose zone from distinct points and along varying. Data on water content variation with time and depth was collected throughout the rainy season of 2021 and 2022 from two sites within this network. The lithology of both sites consists of alternate bands of carbonate sediments with varying levels of porosity. The data generated from these two sites allowed for the continuous tracking of water percolation within the vadose zone and therefore enabled the evaluation of water flow velocities. It was observed that the intensity and frequency of occurence of rain events controls the initiation and downward propagation of wetting fronts along the carbonate litholgical sequence within the vadose zone. The initiated wetting fronts exhibited significant variations in the velocity of the draininage process as a result of the varying lithological sequence. The velocity of the drainage process and the variations in water storage content within the vadose zone were utlised to calculate the rate of groundwater recharge for these two sites.