esculenta) was being grown in Fongafale. The extent of the salinization of the aquifer on Fongafale Islet is the result of both man-made changes to the topography that occurred when the air field was built in World War II by reclaiming swamp land and excavating coral rock from other parts of the islet. These topographic changes are exacerbated by the groundwater dynamics of the islet, as tidal forcing pushes salt water into the surficial aquifer during spring tides. The freshwater lens of each atoll is a fragile system. Tropical cyclones and other storm events also result in wave wash over and extreme high water also occurs during spring tides. These events can result in salt water contamination of the fresh groundwater lens. Periods of low rainfall can also result in contraction of the freshwater lens as the coconut trees and other vegetation draw up the water at a greater than recharge than it can be recharged. The over extraction of ground water to supply human needs has a similar result as drought conditions. See also References Further reading