1.1.1.WATER RESOURCES Geologically, Papua New Guinea is a young country. The presence of high mountain ranges and abundant rainfall leads to high runoff over most of the country. There are nine hydrological drainage divisions (basins) in the country. The largest river basins of the country are the Sepik, Fly, Purari and Markham. Even though the Sepik has the lowest annual discharge, it has the largest catchment area, 78,000km2, followed by the Fly River with 61,000km2, Purari with 33,670km2, and Markham with 12,000km2. The other catchments are less than 5,000km2 in area and very steep. The internal renewable water resources are estimated at 801km3/yr. As the country has an abundance of surface water resources and as there are few large-scale consumers, groundwater resources have not been developed much. However, there is evidence that groundwater is being used increasingly as a source of reliable high quality water. In 1974, 34 per cent of the villages surveyed relied on groundwater from boreholes, dug wells or springs. In the 1970s and 1980s, groundwater was developed for urban water supply schemes in seven major towns. Groundwater resources have not been assessed but it is assumed that most groundwater returns to the river systems and is therefore included in the surface water resources. There are 5,383 natural freshwater lakes in the country. The lakes are mostly small, and only 22 have a surface area exceeding 10km3. Lake Murray is the largest with a surface area of 647km3. In 1986, there were three dams in the country over 15m high. The gross theoretical hydropower potential for Papua New Guinea is 175,000GWh/yr. In 1990, the total installed capacity was 163MW and the annual generation was 438GWh. In 2008, of the country’s total power generating capacity of 580MW, hydropower comprises 220MW (ADB, 2008). The Sirinumu dam, which was officially opened in 1963, provides water for consumption and also produces electricity for Port Moresby (NLA, 1963). The Yonki dam, a 60m high dam of zoned earth fill construction, is a hydroelectricity dam located on the Ramu river in Eastern Highlands Province. In 2009, total dam capacity has been estimated at 665 million m3.

1.1.2.WATER USE In 2005, the total water withdrawal was estimated at about 392 million m3, of which about 1 million m3 (0.3 per cent) was for agriculture, 223.5 million m3 (57.0 per cent) for municipalities and 167.6 million m3 (42.3 per cent) for industries.

(Water Risk Filter)