We directly experience higher tides and more frequent storms, which bring salt-water intrusion and coastal flooding. We have long periods of drought, an endangered supply of fresh water, and bleaching of the coral reefs that cradle our islands. The islands and atolls of Kiribati have limited ground water lenses. Potable ground water in wells has traditionally supplied water for the population but this supply has been failing as a direct result of climate changes that are being experienced. The coral limestone, which supports atolls, is porous and allows seawater to flow through it. The water table oscillates on a daily basis with the tides, and in the long term with the mean sea level. As sea levels have risen, many wells have become contaminated with salt water and can no longer be used.
The ground water supply in South Tarawa is dependent on the size of the land area and as this diminishes as a result of rising sea levels and coastal erosion, so does the size of the water lens. Read this case study about drilling for water in Kiribati. Traditionally there have been two seasons in Kiribati—“Aumaiaki”, the dry season from April to September, and “Aumeang”, the rainy season from October to March. But in recent years the country has experienced unusual and extreme drought-like conditions, even during what has traditionally been the rainy season. As a result rainwater catchment has been greatly reduced. The net result of these factors mean that the water supply in Kiribati falls short of the recommended WHO standard of 50 litres per person per day.
Drilling for water in Kiribati
Binataake Nawere stands bucketing water from his well in the strong afternoon sun at Betio in South Tarawa, Kiribati (pictured above right). “We use well water for washing clothes and dishes,” says 60-year old Binataake as he fills a large container with groundwater. The residents of Betio and many of Kiribati’s residents often rely on well water to meet their needs. Fresh water is in short supply in Tarawa. The average house in Betio only receives tap-water for an hour and a half every 2 days.
The population of South Tarawa has grown from only 3,013 in 1931 to over 40,311 by 2005. Such rapid growth has led to a population density as high as 15,000 people per square kilometre on the narrow atoll islands. Tokyo, famous for overcrowding, has a population density almost three times lower.
A KAPII (Kiribati Adaptation Program – Pilot Implementation Phase II) working crew completed a two month long project to drill boreholes required to assess the thickness of the underground freshwater lens in Tarawa. The lens is made up of rain water that has infiltrated the soil of the atoll. This freshwater then actually floats on top of a layer of saltwater directly beneath each island.
“It is my first time to see how it works, it is really exciting,” says Tiaeke Tio, an i-Kiribati technician as he stands in front of the KAPII drilling rig. Measuring boreholes have been installed by the project at Tabiang, Tabuki and Nubeina in North Tarawa and at Bikenibeu, Bairiki and Betio in South Tarawa. These boreholes will build on the network already in place and enable ongoing assessments of the freshwater lens to be made.
The team has been led and trained by Colin Benjamin, an experienced driller from the UK. When Colin arrived in Tarawa he had some concerns about training a local team to drill. “I thought the local language and labour issues were going to be difficult and therefore training would be hard. But it was the opposite, the i-Kiribati were very good,” says Colin with a big smile on his face.
“We can now measure where the freshwater lens starts and finishes and how this changes over time. This changes as it is affected by the amount of water pumped out, rainfall, tide and climate change,” says Colin as they complete the last borehole in the grounds of the Betio Sport Complex.
This new information is necessary to plan for the sustainable use of water in Tarawa. If too much water is extracted at a location where the lens is not thick enough, saltwater is pumped up from below the freshwater lens causing contamination of the freshwater and making it unusable.
The 40,311 residents of South Tarawa are currently drawing on a groundwater supply that can only support half the population. Water scarcity is a critical issue and the risk of saltwater contamination of the freshwater lens is ever present, so discovering new water resources are critical.
Training an i-Kiribati team to operate the required equipment is vital for the sustainability of ground water monitoring in Tarawa. “As far as the local drilling crew is concerned, we have managed to put together a very efficient team that is learning a lot,” continues Colin. Tiaeke nods his head and responds, “We have been drilling down to 15 or 20 metres, getting all the parts together and getting the machine going. I am learning something new.”
“It is good to learn about looking after the water here,” says Tiaeke as he describes the importance of the KAPII team’s work to Kiribati. “It is where my ancestors lived, where I grew up, where my family is. I love the place and I love this country.”
Binataake knows well the importance of the freshwater lens. “When the government piped water supply is not operating and there is no rainwater, we only have the water from our well,” he says lifting another full bucket, something he hopes to be able to rely on, now and into the future.
The Government of Kiribati KAP project is supported by the World Bank, the Global Environment Facility, AusAID and NZAID. The key goal is to reduce Kiribati’s vulnerability to climate change, climate variability and sea level rise.