You have entered the website of the Water and Environmental Research Institute of the Western Pacific (WERI) at the University of Guam. We are currently six faculty and five staff and our mission is to seek solutions through research, teaching and outreach programs, to issues and problems associated with the location, production, distribution and management of freshwater resources in Guam, the CNMI and the FSM.
In Guam, as in other oceanic island environments, rainfall has a significant chloride ion concentration. As a result, there is a relatively simple and straightforward method of estimating groundwater recharge by considering the chloride ion as a tracer which is concentrated by evapotranspiration processes.
The chloride ion concentration of rainwater in Guam is about 4.5 mg/L. the freshest part of the northern lens is about 11.8 mg/L. Taking the 11.8 mg/L value as an indicator of the chloride ion concentration of recharge, the average annual recharge rate is estimated at 38 percent of the 218 cm/yr average annual rainfall, or about 83 cm/yr.
This estimate agrees very well with previous work which utilized other independent methods of determining recharge rates.
