WorldWide Drilling Resource

Cory Miller President Of昀ce: 903-725-6978 7355 E SH 154 Winnsboro, Texas 75494 “Mud Pumps for the 21st Century” 20 JULY 2022 WorldWide Drilling Resource® Freshwater in the Sea at Easter Island Adapted from Information by Binghamton University Easter Island is a remote Chilean territory located in Polynesia. European explorers in the late 1700s reported people of Easter Island appeared to drink directly from the sea. Today, animals, most famously horses, can be seen doing the same thing. What’s going on? While surrounded by a vast ocean, freshwater is a scarce commodity on Rapa Nui, as the island is known to native inhabitants. No rivers or streams cross its surface, and it only has three small crater lakes which can dry up during periodic droughts. Due to a quirk of geology on the island, rainwater immediately sinks down through porous bedrock, where it feeds an underground aquifer, explained Binghamton University’s Robert DiNapoli, a postdoctoral research associate in environmental studies and anthropology. This freshwater emerges at spots on the coastline known as coastal seeps. “At some of these locations on the shoreline, there is so much water coming out (from the seeps) that it’s basically fresh. It’s somewhat salty, but not unpalatably salty,” said DiNapoli. “It’s just not the best tasting water, basically.” DiNapoli and his colleagues recently used thermal imaging drones to detect the location of coastal seeps. As part of their research, they explored the way ancient communities used these seeps on an island where droughts are common. In addition to collecting rainwater, the Rapa Nui people also constructed basin-type wells called puna, intercepting the stream from the aquifer before it reached the sea. They also built underwater dams in the ocean to prevent seawater from mixing with freshwater at the seep sites, although these structures have long since crumbled away. “It again provides an interesting example of how the people there were responding to the constraints of the island,” added DiNapoli. “They were faced with a very difficult place to live and they came up with these interesting strategies for survival.” As the first European visitors noted, inhabitants also drank directly from the ocean at the seeps. The island’s current residents still pump water directly from these freshwater spots in the sea and use it to water crops and provide water for livestock. In previous research, DiNapoli and colleagues noted Easter Island’s famous archaeological features, such as the moai platforms, correlate closely to the location of freshwater resources. “This is where they’re doing their ceremonial activities; this is where they’re building their villages,” said DiNapoli. The study’s results are the jumping off point for another research project funded by a National Geographic grant to identify the location of coastal seeps throughout the island. One of the questions they hope to answer is how coastal seeps respond to lengthy droughts. During their last research trip, the island was experiencing a multiyear dry spell, which dried up two of the crater lakes and sunk the third to low levels. “But we identified these coastal seeps all around the island. That suggests that when the island experiences these drought events, the seeps are one of the last water sources to be affected by it,” explained DiNapoli. One potential explanation: When the water goes underground after heavy rain, it likely stays in the aquifer for several years before discharging into the ocean. In their upcoming fieldwork, DiNapoli and fellow researchers will try to confirm this and determine how long it takes rainwater to make its underground journey to the sea. Horses on Easter Island are sometimes seen drinking directly from the ocean. The moai statues are Easter Island’s most famous archeological features. These statues are most often found near sources of freshwater. WTR