The Freshwater Cycle in the Marshall Islands

By Christina Burchette

At just three to six feet above sea level and surrounded by the rising tides of the North Pacific, citizens of the Republic of the Marshall Islands (RMI) are vulnerable to some of the most impending climate change impacts. They’re threatened by limited freshwater resources, persistent drought conditions, and the rising sea level. The need and desire to safeguard against these impacts is strong, but due to their very isolated location, there aren’t a lot of resources or expertise readily available to help the islanders adapt to their changing environment.

Dr. Bill Shuster (middle row, sitting) and the embassy staff. Photo credit: US Embassy – Majuro

Research hydrologist Dr. Bill Shuster went on detail as an Embassy Science Fellow to the US Embassy on Majuro, the most populous atoll in the Republic of the Marshall Islands, to support the embassy on science and technology matters and share his scientific expertise to improve the island’s freshwater resource management.

The people of Majuro rely on a limited number of freshwater sources: a reservoir fed by runoff from the airport runways, freshwater lenses (freshwater that floats on a saltwater table), tanks that collect runoff from roofs, imported water, and volume from reverse-osmosis units that convert seawater to potable water. Since the islands are low-lying, the reservoirs, lenses, and runoff tanks can become polluted or structurally damaged by over-wash of saltwater during storms. In addition, extreme drought conditions mean that managing and monitoring freshwater gains and losses are all critical to improving the island’s water security and drought resilience.

To help the island take steps toward security and resilience, Dr. Shuster worked through the Embassy with local government agencies, students, and residents to identify gaps in water resources data and barriers to filling these gaps. He also led a team of students and RMI Environmental Protection Authority staff to measure and understand the role that the soils play in the local freshwater cycle.

A sandy shore on the west side of the Majuro atoll.

What they found is that different areas of the island yielded different results about water quality. For instance, Dr. Shuster and colleagues showed how the freshwater lens located in the urban, east side of Majuro had little freshwater due to a lack of recharge, and any pumping would have drawn sea water in. On the other hand, the more productive freshwater lens on the rural, west side of the island, was situated under deep soils, allowing for freshwater recharge and making the lens a viable freshwater supply. Yet, the viability of this lens was threatened by over-pumping, saltwater intrusion, and pollution leaching in from agricultural development.

After gathering this sort of data, Dr. Shuster worked with staff at the Majuro and Sewer Company to identify gaps in an overall water balance model to plan for drought management and adaptation and develop strategies to manage and close data gaps.

While his trip to the islands was only seven weeks long, Dr. Shuster and his colleagues’ research efforts brought awareness to the island’s water resource issues and will help residents make data-based decisions that contribute to water security and a sustainable future on this remote atoll.

About the Author: Christina Burchette is an Oak Ridge Associated Universities contractor and writer for the science communication team in EPA’s Office of Research and Development.