HAWAII VOLCANIC-ROCK AQUIFER STUDY
NEED FOR REASSESSMENT OF HAWAII'S GROUNDWATER RESOURCES
Well drilling and aquifer testing, as well as numerous hydrologic studies, have added much new information since the last national groundwater assessment in Hawaii (photo by Scot Izuka).
Reassessment of Hawaii’s groundwater resources is needed because:
- Groundwater in Hawaii is a critically important resource. Groundwater supplies much of the freshwater taken for human uses. Groundwater also supplies freshwater discharge to springs, streams, and the coast that supports both human uses and fragile ecosystems.
- Hawaii has limited capacity to store fresh groundwater. The islands and their aquifers are small and isolated from each other by surrounding seawater. Seawater also underlies most of the fresh groundwater resource.
- Factors affecting groundwater have changed. Since the last assessment in the 1980s-90s, groundwater withdrawal has increased in many areas but decreased in some areas. Changes in agriculture and vegetation have altered the groundwater recharge in some areas. Effects of climate change have been detected in rainfall and stream-flow records.
- New information relevant to groundwater in Hawaii has become available. Since the last assessment, studies have advanced knowledge in climate, geology, and hydrology in Hawaii. Recent studies indicate that early conceptual models do not fit all parts of Hawaii.
- Hydrologic technology and methods of analysis have advanced. For example, new three-dimensional, solute-transport and density-dependent groundwater flow models are now available to increase capabilities for simulating the saltwater/freshwater systems in Hawaii aquifers, and methods for computing groundwater recharge have improved.
- Information needed for resource management and protection. Updated information on the current condition of Hawaii’s groundwater resources and how they have changed as a result of natural and human factors is essential for resource management and protection.