Oral Presentation Australasian Groundwater Conference 2017

Hydrogeology of West Ambae, Vanuatu as inferred by geo-electrical resistivity survey (398)

Andreas Antoniou 1 , Peter Sinclair 1 , Aminisitai Loco 1 , Erie Sami 2 , Anesh Kumar 1
  1. Water and Sanitation Programme, Geoscience Division, Pacific Community
  2. Department of Water Resources, Vanuatu

As part of the resilience-building component of SPC’s recovery support for Tropical Cyclone Pam funded by KfW and in collaboration with Vanuatu’s Department of Water Resources, geophysical surveys were carried out using electrical resistivity in the N’dui N’dui and Walaha districts of West Ambae, Vanuatu, to assist with identifying fresh groundwater resources potential and optimal drill targets. In the absence of drilling and subsurface information in general, survey locations were selected based on surficial features including eruptive cones and fissures, and lineaments with the potential to cause high-elevation groundwater impoundment. In addition, geological maps were used to infer locations where groundwater may occur at relatively shallow depth along contacts between lava flows of different age. Ten geo-electrical transects were performed (> 5 km total length) allowing for the 2D representation of the spatial distribution of electrical resistivity up to 90 m depth. The interpretations suggest a limited presence of localized aquifers, either impounded within fractured basalt or perched due to the presence of impervious formations like ash or tuff layers between lava flows. The presence of springs at higher elevations supports the conceptual model of perched aquifer systems while the existence of brackish water springs along the coast suggests that infiltrating rainwater finds its way through the fissured basaltic lava flows and highly porous scoriae and eventually discharges into the sea. The small number and limited extent of identified potential targets highlights the value of performing detailed resistivity surveys prior to any drilling operations to minimize costs and risks associated with “wildcat” drilling.

  • We are offering awards for Career and Early Career presentations and posters. Please indicate length of time since highest degree completed.: 5 Years or more
  • We are offering awards for Career and Early Career presentations and posters. Please indicate length of time since highest degree completed.: 5 Years or more