The EU Water Framework Directive (WFD) requires the achievement of good status in the water environment through the implementation of River Basin Management Plans (RBMP). The long-term impact of these plans and their contribution to the achievement of good status is however generally difficult to predict and quantify, thus presenting an important constraint in this planning process. Numerical models are a tool which can enable water managers to predict the effective impact of measures on a water-body scale, and therefore enable a more reliable assessment of the effectiveness of the plan in achieving the set objectives. The FREEWAT Project aims at the development of an open source and public domain GIS integrated modelling environment for the simulation of water quantity and quality in surface water and groundwater bodies. One of the pilot initiatives under this project focuses on the island of Gozo (Malta) where the FREEWAT modelling environment is being used for the development of a numerical model of the mean sea-level groundwater body present in this island. This paper assesses the integration of this numerical model in the river basin management framework of the island, in support of the achievement of the good status objectives for this groundwater body. The paper focuses on the application of the FREEWAT based numerical model for the assessment of the impact of the groundwater management strategies envisaged under Malta's 2 nd RBMP on the quantitative status of the groundwater body. Furthermore, it provides an outlook on the application of the model to assess the response of the groundwater body to changing natural conditions arising due to the projected impact of climate change. In so doing, the modelling framework provides water managers the opportunity to consider within the basin river management framework the necessary flexibilities to ensure the continued achievement of the WFD's objectives under future scenarios.

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<p>A method to conceptualise the assessment of the impact of sea-water intrusion in island and coastal aquifer systems is being proposed.  The method will enable the undertaking of a first assessment of the sea-water intrusion problem, hence providing an early-stage and simple to apply “warning system” enabling the informed and timely application of mitigation measures intended to protect the quantitative and qualitative status of the aquifer system. The method proposes the discretization of the aquifer to enable the correlation of the current aquifer “freshwater domain” with reference conditions representing the aquifer system under undisturbed conditions.  The “freshwater domain” is defined by the volume of water between the piezometric surface and the seawater interface, and can be obtained from numerical models, where available, or the application of simple analytical approaches such as the Ghyben-Herzberg solution. . The dynamic of the seawater intrusion is defined as the change in natural “freshwater domain” and chloride concentrations within it. Therefore, the method is applicable to island and coastal aquifers with low-data availability, and in particular to cases where a numerical-model is not-yet developed. The application of the method will enable the quantification of sea-water intrusion impacts at an aquifer scale, enabling the visual-conceptual representation of the sea-water intrusion affected area, as well as identify the level of intrusion.  The method also enables the temporal assessment of sea-water intrusion, identifying the evolution of intrusion throughout the exploitation period of the aquifer system.  The method has been implemented in a GIS tool, and applied to the Mean Sea Level Aquifer system in Malta.</p><p> </p><p>Aknowledgement: This research has been partially supported by the GeoE.171.008-TACTIC project from GeoERA organization funded by European Union’s Horizon 2020 research and innovation program and by the SIGLO-AN project (RTI2018-101397-B-I00) from the Spanish Ministry of Science, Innovation and Universities (Programa Estatal de I+D+I orientada a los Retos de la Sociedad)</p><p> </p>

<p>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.</p>