The Impact of Predicted Climate Change on Groundwater Resources in a Mediterranean Archipelago: A Modelling Study of the Maltese Islands

Michele De Biase,Francesco Chidichimo,Mario Maiolo,Aaron Micallef

doi:10.3390/w13213046

Abstract

The effects of changes in climate predicted for 2100—reduction in recharge, increase in water demand and sea-level rise—on groundwater volume and saltwater intrusion have been quantified in the Maltese Islands, an archipelago located at the center of the Mediterranean Sea. A three-dimensional density dependent and heterogeneous model, working in transient conditions, was developed based on morphological and geological information. The hydraulic conductivity and porosity of the lithological formations were derived from previous tests and studies conducted on the islands. The complex fault system intersecting the area has also been included in the model. The results show that among the three considered factors affecting groundwater resources, the most significant is the increase in water demand, which is closely followed by the decrease in groundwater recharge. Sea-level rise plays a marginal role. The 80-year simulation period showed that these combined impacts would cause a loss of more than 16% of groundwater volume.

Highlights

The predicted effects of climate change will worsen current environmental problems globally such as land use issues, pollution, water scarcity and biodiversity decline [1]
Water 2021, 13, 3046 clude the following: (i) the Lower Coralline Limestone (LCL)—a 1000 m thick succession of algal foraminiferal limestone; (ii) Globigerina Limestone (GL)—fine-grained biomicrites up to 207 m thick, which are further subdivided into Upper (UGL), Middle (MGL) and Lower (LGL) Globigerina Limestone; (iii) Blue Clay (BC)—up to 75 m of slightly consolidated hemipelagic clays and marlstones; (iv) Greensand (Gs)—poorly cemented bioclastic and glauconitic limestones that are up to 11 m thick; (v) Upper Coralline Limestone (UCL)—an up to 100 m thick shallow water reef complex (Figure 1)
The study quantifies the effects of reduction in recharge, increase in water demand and sea-level on groundwater volume and saltwater intrusion

Summary

Introduction

The predicted effects of climate change will worsen current environmental problems globally such as land use issues, pollution, water scarcity and biodiversity decline [1]. The most vulnerable societies are characterized by insufficient observation systems and monitoring equipment, and they lack impact-based models. This is the case of the Mediterranean region. It is expected that the future average annual temperature increase will be 2.2 ◦C in 2040, possibly exceeding 3.8 ◦C in 2100 in some Mediterranean regions [2,3]. Climate models suggest scenarios with reduced rainfall in the coming decades [4]. Irrigation, for example, represents 50–90% of the total Mediterranean water demand [9] This demand, which is projected to increase by 4–18% by the end of the century due to climate change alone, may increase by 22–74%

Methods

Results

Discussion

Conclusion