Evaluation of Fresh Groundwater Lens Volume and Its Possible Use in Nauru Island

Abstract

A proper management of fresh groundwater lenses in small islands is required in order to avoid or at least limit uncontrolled saltwater intrusion and guarantee the availability of the resource even during drought occurrences. An accurate estimation of the freshwater volume stored in the subsoil is a key step in the water management decision process. This study focused on understanding the hydrogeological system behaviour and on assessing the sustainable use of the groundwater resource in Nauru Atoll Island (Pacific Ocean). A first phase, concerning the hydrogeological characterization of the island, highlighted the occurrence of few drought-resilient freshwater lenses along the seashore. The second part of the study focused on the characterization of a freshwater lens found in the northern coastal area and identified such area as the most suitable for the development of groundwater infrastructures for water withdrawal. The characterization activities allowed quantifying the freshwater lens thickness and volume in order to assess the capability to satisfy the population water demand. A geo-electrical tomography survey was carried out, and a 3D density-dependent numerical model was implemented in SEAWAT. The model results demonstrated that in small islands freshwater can unexpectedly accumulate underground right along the seashore and not in the centre of the island as is commonly believed. Furthermore, the model can constitute a useful tool to manage the groundwater resources and would allow the design of sustainable groundwater exploitation systems, avoiding saltwater intrusion worsening.

Groundwater Hydrological Model Simulation

“…The paper "Evaluation of Fresh Groundwater Lens Volume and Its Possible Use in Nauru Island" [5] presents a particular case study concerning the groundwater system characterization and modelling of the Nauru Atoll Island (Pacific Ocean). After a large-scale study for detecting the location of freshwater lenses, a local-scale study was made, aimed at quantifying the freshwater lens thickness and volume for supply uses through a geoelectrical tomography survey, and a 3D density-dependent numerical model implemented in SEAWAT.…”

Time Scale of the Formation of Fresh Groundwater Lens on an Atoll Island under the Influence of Land Reclamation

“…Atoll islands are characterized by their ring-shaped or their ring or horseshoe-shaped coral reefs with enclosed or semienclosed lagoons. Predominantly located in the Pacific and Indian Oceans, these islands are primarily governed by Small Island Developing States (SIDS). , Characteristically small and with elevations a few meters above sea level, atolls possess distinctive hydrological systems and topographical features. When wide enough, these islands can retain rainfall in their aquifers.…”

Distribution and Origins of Hardness in Shallow and Deep Groundwaters of the Hebei Plain, China

“…Globally, groundwater is the main source of drinking water for more than 2.5 billion people, and about 70% of groundwater abstraction is used for agricultural irrigation [1]. Especially in areas with insufficient surface water, such as the Hebei Plain (HBP) and islands, groundwater is often the major water resource for drinking and irrigation purposes [2,3]. For example, groundwater accounted for more than 52% of the total water supply in the Hebei Province of China in 2019 [4].…”