Acacia Water participates in Tonga scoping mission

The Dutch Government has established a Dutch Risk Reduction (DRR) team of water experts that can be called upon by countries to provide advise on how to resolve urgent water issues. A long drought caused by the 2015 El Niño event caused salinization of fresh groundwater in several village water supply wells in Tongatapu, the main island of the the Kingdom of Tonga. This resulted in an application for DRR-team assistance and a DRR-team consisting of Mr. Sjef IJzermans and Dr. Maarten Waterloo carried out a scoping mission in November 2016 to assess available groundwater water and the demands for public and agricultural water supply. Tongatapu is composed of limestones and fresh water is found as a thin lens of less than 20 m thickness floating on saline water.  The lens thickness becomes less during droughts by outflow along the coast and by groundwater abstractions. During the mission data were collected in Fiji and Tonga and future developments in water resource demands were discussed with representatives of the government, the public water supply and the agricultural sector.  A field excursion was organised by the Department of Geology to view the geology, hydrological measurements, agricultural practices, public water supply and exfiltration zones along the coast. There is an increasing demand for water for both domestic as agricultural use, whereas climate change is likely to increase the frequency of extreme droughts. Everyone agreed that it is in their interest to have regulations for groundwater use and that more knowledge about the functioning of the hydrological system is needed for the implementation and execution of these regulations. The DRR-team members will submit a report to provide better insight about the availability of groundwater during droughts and the future water demands for domestic and agricultural use.