Hydrology of basalt aquifers, Hawaii USA

Research has been done at basalt aquifers in Iceland (Skaftafell national park) and Idaho (Palouse basin). Often the groundwater level in such aquifers is declining rapidly due to large scale water abstractions. A good knowledge on the physical properties of basalt formations (porosity and hydraulic conductivity) is needed to develop adequate water management plans.
At Big Island (Hawaii, USA) fresh basalt is formed continuously by the Kilauea volcano. At many locations fresh outcrops and cross sections can be found and studied in detail. What is the general distance between fractures in the pahoehoe basalt? What is the effective porosity? What is the REV (Representative Elementary Volume)?
Objective is to link the results of the field study in Hawaii to literature and to the field studies in Idaho and Iceland.