MWSC Airport Reservoirs

Managing drought in a high rainfall Atoll country
A Gale, H deBrum
Publication Date (Web): 1 May 2017

It is hard to believe that when a community receives in excess of 3000mm/year of rain (almost five times Melbourne’s average annual rainfall) that water could be so precious. Yet that is exactly the situation in the Marshall Islands (RMI), an island country comprising a series of 29 coral atolls and five islands in the Pacific just north of the equator. The islands extend 1150 km north south and 1300 km east-west, about 4100 km from Sydney and 3200 km from Honolulu.

This tiny republic of some 53,000 inhabitants has major water supply challenges, particularly on the two main islands, Majuro (28,000 people in 970 ha at 6.8 people per household) and Ebeye, (10,000 people in 40 ha at 8.4 people per household).

The discussion in this paper focusses primarily on drought management for Majuro, with brief discussions on Ebeye and the outer islands to demonstrate the diversity of approaches.

Majuro Water and Sewer Company (MWSC) is the State-Owned Enterprise (SOE) with responsibility for water supply to Majuro island. The water supply system is relatively complex, with multiple sources and treatment plants. The primary water source is the airport runway, which meets the needs of the greater community, although the Laura groundwater lens provides substantial supply during droughts. Another major source is rainwater harvesting, upon which 75 percent of the community relies for their sole supply.  A “drought” occurs in two to four weeks with low rainfall when rainwater tanks empty and there is no other source of supply.

Majuro suffered a “drought” in early 2016, resulting in the declaration of a State of National Emergency by the RMI government, followed by declaration of a State of Disaster by the USA President, resulting in emergency water supplies and significant international support to the RMI.

MWSC’s management of the 2016 drought was successful in ensuring that Majuro avoided a major disaster by:

  • Application of its drought management plan prepared in December 2015, 
  • Better definition of the safe yield of the Laura groundwater lens to ensure the lens was not negatively impacted,
  • Optimal management of the resources from the airport catchment using a water balance model developed by the primary author,
  • Coordination with commercial drinking water suppliers to ensure availability of drinking water,
  • Coordination with RMI EPA for development of emergency water tankering regulations to enable the tanker demand to be met
  • Leasing an emergency Saltwater Reverse Osmosis (SWRO) plant as the primary risk management tool, albeit that the drought broke before the plant arrived in Majuro and it was shipped back to Australia unopened.  However, it was a major risk management decision in ensuring that 28,000 people were not without adequate water supply.

The primary learning from the 2016 drought amongst many was that water resource management is critical - the issue was primarily one of effective water resource management rather than a severe shortage of water.  Water resources will be an ongoing challenge for RMI but continuing development of good planning and management practices by the leaders of MWSC and a better understanding of drought management by the general community will mean that 3000 mm of rain per year will be adequate.

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