Saltwater Intrusion and Freshwater Storage in Sand Sediments along the Coastline: Hydrogeological Investigations and Groundwater Modeling of Nauru Island

Luca Alberti,Martino Cantone,Ivana La Licata

doi:10.3390/w9100788

Abstract

Water resources sustainable management is a vital issue for small islands where groundwater is often the only available water resource. Nauru is an isolated and uplifted limestone atoll island located in the Pacific Ocean. Politecnico di Milano performed a feasibility study for the development of sustainable use of groundwater on the island. This paper focuses on the first phase of the study that concerns the conceptual site model development, the hydrogeological characterization and the 2D model implementation. During the project, different activities were performed such as GNSS topographic survey of monitoring wells and groundwater level surveys taking into account tidal fluctuation. This data collection and the analysis of previous studies made it possible to identify the most suitable areas for groundwater sustainable extraction. The characterization findings suggested, unlike previous studies and surveys, the presence of only few drought resilient thin freshwater lenses, taking place in low conductivity sandy deposits, unexpectedly next to the seashore. Thanks to the 2D modeling results, it has been possible to clarify the mechanism that allows the storage of freshwater so close to the sea.

Highlights

The integrated and sustainable management of water resources in small island countries is a fundamental issue for health and social well-being, protection of the environment and development of the economy
Werner et al [5] have shown in their review of the state of knowledge of atoll island groundwater that over fifty years of investigation have led to important advancements in the understanding of atoll hydrogeology, but a paucity of hydrogeological data persists on all but a small number of atoll islands
This paper focuses on the first step of the project and on preliminary design of infrastructural actions for groundwater sustainable exploitation

Summary

Introduction

The integrated and sustainable management of water resources in small island countries is a fundamental issue for health and social well-being, protection of the environment and development of the economy. It becomes a very high-level priority because of the strong limited nature of resources, worsened by climate change. Buada studies [27] had determined two areas with a freshwater thickness higher than 5 m: one located close to the other near the S15, S2S4 monitoring wells.

Methods

Results

Discussion

Conclusion