Coastal groundwater discharge and the ancient inhabitants of Rapa Nui (Easter Island), Chile

Mirror Macro-Imagineering Water Supply Megaprojects: Pipedream Chile-California Complementarity? (Macro-Imagenharia de Megaprojetos Espelhados para Abastecimento de Água: Aquedutos Chile/California como Soluções Complementares Sonhadas?)

“…Team Geographos, surely characterizable as upstarts in the offshore infrastructure business, here boldly suggests several possible improvements for the Subma-River concept as it is here applied to Chile's coastline. First noticed elsewhere during the mid-1960s [9], beach-sited groundwater springs supported pre-historic human populations living on the distant island of Rapa Nui, Chile [10]. Though known coastal aquifers are present in the northernmost region of Chile, most known to exist in the Atacama are located in fluvial valleys on land, none yet known to be offshore.…”

Drought, freshwater availability and cultural resilience on Easter Island (SE Pacific) during the Little Ice Age

“…A different view has been proposed more recently, according to which fresh/brackish coastal seeps could have been the major source of water for the survival of the ancient Rapanui society during the LIA climatic drought (Brosnan et al, 2018). Such a conclusion is based on the consideration that other potential freshwater sources (permanent lakes, springs, ephemeral streams and pools) would not have been sufficient to support a population of thousands of individual s. According to these authors, the lake of Rano Kao is too difficult to access to have been a routine source of freshwater, and moreover, there is no archeological evidence of human habitation on its shores.…”

“…The same would be true for Rano Aroi, whose spring is unlikely to have been useful to satisfy the needs of the whole island due to its remoteness. Temporary streams and ponds were also considered too ephemeral (hours to a few days after a rain event) for such purpose, and some receptacles found on archeological sites to collect rainwater (taheta) were too small and too susceptible to water evaporation for large-scale human usage (Brosnan et al, 2018). This, together with the absence in the archeological record of large water containers and intense habitation near lakes and marshes, led the conclusion by these authors that coastal seeps would have been crucial for prehistoric Rapanui subsistence.…”

“…The remains of these structures, called puna, have been found at several sites along the island's coasts, which were the preferred sites for the Rapanui to live. Therefore, fresh/brackish water sources would have been frequent, widespread and close to the populated sites (Brosnan et al, 2018). According to DiNapoli et al (2019), the ahu, in addition to their ritual meaning, would have a signaling function to indicate the situation of such coastal seeps.…”

“…In this paper, this phenomenon is called the intra-island migration hypothesis. In contrast, the coastal groundwater hypothesis proposes that freshwater was obtained from coastal groundwater seeps and explicitly dismisses other possibilities (Brosnan et al, 2018;DiNapoli et al, 2019). This paper briefly summarizes these two proposals and aims to show that they may be complementary, rather than mutually exclusive.…”