WRRCTMR No.75 Aquifer Classification, State of Hawaii

Abstract

A consistent classification and nomenclature of the aquifer systems in the state of Hawaii do not exist in spite of the fact that groundwater is an essential water supply source in each island. The classification of water resources currently in use ignores aquifer features and boundaries and is based, instead, on topographic and judicial boundaries. One of the consequences is confusion in terminology because each investigator or describer of the resources often arbitrarily assigns aquifer names. A classification scheme is proposed which starts with the island as the largest component and the aquifer unit as the smallest. Each island is divided into Sectors in which similar generalities of hydrogeology prevail. Sectors are divided into systems in which hydrogeological and groundwater hydraulic connections are stronger, and the systems are further divided into units categorized by hydrological and geological features. A single code, consisting of a number for an island and letters for all other characteristics, identifies each aquifer unit. The code is open ended and may be expanded to include other aquifer features. For the six major islands, the classification scheme includes 21 sectors, 64 systems, and 192 aquifer units. The intent of this study is not to fix the classification at this time, but to provide an incentive for standardization.