Between 2016 and 2019, BRGM, at the request of the Polynesian Ministry of Culture and Environment, undertook a programme to provide French Polynesia with efficient tools for the management and exploitation of groundwater resources, in order to meet the quantitative and qualitative needs of the country in a context of climate change.
2 November 2021
Source Vaima, Tahiti

Vaima spring (Tahiti, 2017).

© BRGM

The need

In French Polynesia, groundwater is extensively used, but its availability varies according to the topology of the islands. Abundant on the islands with high elevation, the resources are limited to a more or less brackish water layer on the atolls. Furthermore, insularity makes these resources vulnerable and pressures are also increasing due to growing needs. In order to offer French Polynesia sustainable development conditions that respect these resources, BRGM has undertaken a complete programme, including hydrogeology, development of an information system and water conservation.

The results

Detailed hydrogeological investigations on an island with high elevation, an island with mixed topology, and an atoll, carried out in Tahiti (on two catchment areas), Moorea, Ua Pou and Rangiroa have made it possible to propose solutions for securing the drinking water supply of four of the five areas studied. The municipalities concerned therefore now have the necessary knowledge to undertake operational research.

In terms of regulations, BRGM participated in the process of revising the procedure for occupying the public river domain, issued recommendations on integrated resource management after studying the situation in several countries in the Pacific zone, and assessed the financial impact of the generalisation of a water abstraction fee.

Through training sessions, the programme also contributed to the transfer of external knowledge adapted to local realities. The sessions dedicated to the digital tools implemented (water point repository and VAITEA internet portal) have notably enabled the relevant authorities in French Polynesia and the municipalities to acquire the skills needed to enrich and animate them.

In the short term, these management and communication tools should contribute to the emergence and structuring of a “groundwater” community and, ultimately, make a significant contribution to defining and implementing Water Policy in French Polynesia.

Prélèvement en vue du dosage des CFC dans les eaux souterraines de la vallée de la Punaruu, Tahiti

Sampling for CFCs in groundwater in the Punaruu Valley (Tahiti, 2018).

© BRGM

Using the results

The multidisciplinary approaches implemented in this programme have proven to be robust and could be replicated for the study of new islands. The use of modern, airborne, geophysical investigation techniques is also recommended if French Polynesia wishes to engage in larger scale reconnaissance.

The partners

  • Ministère de la Culture et de l’Environnement (MCE)