Modelling the response of fresh groundwater to climate and vegetation changes in coral islands

In coral islands, groundwater is a crucial freshwater resource for terrestrial life, including human water supply. Response of the freshwater lens to expected climate changes and subsequent vegetation alterations is quantified for Grande Glorieuse, a low-lying coral island in the Western Indian Ocean. Distributed models of recharge, evapotranspiration and saltwater phytotoxicity are integrated into a variable-density groundwater model to simulate the evolution of groundwater salinity. Model results are assessed against field observations including groundwater and geophysical measurements. Simulations show the major control currently exerted by the vegetation with regards to the lens morphology and the high sensitivity of the lens to climate alterations, impacting both quantity and salinity. Long-term changes in mean sea level and climatic conditions (rainfall and evapotranspiration) are predicted to be responsible for an average increase in salinity approaching 140 % (+8 kg m-3) when combined. In low-lying areas with high vegetation density, these changes top +300 % (+10 kg m-3). However, due to salinity increase and its phytotoxicity, it is shown that a corollary drop in vegetation activity can buffer the alteration of fresh groundwater. This illustrates the importance of accounting for vegetation dynamics to study groundwater in coral islands.

Islands: Nature and Culture

Islands are contradictory places: they can be remote, mysterious spots, or lively centres of holiday revelry. They are associated alternately with escape, imprisonment, holiday and exile, and their exotic, otherworldly beauty has inspired artists and writers across the centuries. Islands have been sites of immense political, creative and scientific importance from Charles Darwin's enlightening voyage to the Gálapagos Islands, which resulted in his groundbreaking theory of evolution, to the moat-encased prisons incarcerating the world's most dangerous convicts.
Despite the common view of islands as earthly paradises, their often small size means they have restricted resources and limited opportunities for their inhabitants to thrive. In response, islanders have welcomed or sternly rejected, the fresh opportunities offered by turning their homes into tourist destinations. For people seeking beautiful landscapes, solitude or exciting adventure, islands are the most popular holiday spots in the world. They entice the rich and famous, and their allure has provided refuge and inspiration for artists and writers, from Paul Gauguin in Tahiti to George Orwell on Jura in the Hebrides, and general visitors alike.
Filled with illustrations, Islands is a comprehensive exploration of the geographical and cultural aspects of island life – their habitations and environments, their permanent residents and vast transitional populace, their colonial history and their enduring appeal to people around then world.