Interpretation of pumping test data from large diameter wells on an oceanic island

Estimation of aquifer parameters is vital for the assessment of groundwater potential and groundwater now regime. On an oceanic island where fresh wat er lens is fragile and sensitive to various stresses, it is even more essen tial that in order to assess the potential of fresh water lens and the effe ct of various stresses on the fresh groundwater regime the parameters shoul d be representative to the field hydrogeological set up. Pumping tests cond ucted on existing large diameter wells on an oceanic island have been analy zed. A finite difference method has been used to take into account the well storage, partial penetration and upconing carried out to estimate aquifer parameters from the pumping test data. Field examples are described.