DesalData Weekly - October 14th, 2015

Posted 14 October, 2015 by Mandy

The Namibian government has made progress towards finalising a deal to purchase the country’s sole desalination plant.1 Since September 2014, a Cabinet-appointed government negotiating team has been working with the privately-held company, Areva Resources, to purchase the plant, located in the Erongo region, 30km from the capital, Swakopmund. The Omdel water-supply system and the Kuiseb River have long supported the region’s coastal towns and businesses, however, their volumes have been diminishing over the years. In 2009, water shortages stopped the Erongo region’s uranium mining production for the first time.

The Areva plant currently supplies water exclusively to the Husab and Rössing mines; and will continue to support these mines after officials finalise its purchase. Sugnet Smith, of Areva Resources Namibia, has reported that the company is not able to reveal the plant’s purchase price prior to the conclusion of negotiations. Assuming the sale concludes smoothly, the Namibia Water Corporation (NamWater), owned by the government’s Ministry of Agriculture, will soon assume responsibility for distributing at least 11 million cubic metres of water annually; however, the plant is capable of producing 20 million cubic metres.3

Namibia’s Kuiseb River, an ephemeral river with a run-off of 20 million m3/year Credit: African Seer ²

Beneath the red cliffs of western Colorado, the Dolores River perpendicularly crosses the Paradox Valley, instead of flowing down the length of it. In 1875, the geologist and surveyor Albert Charles Peale named the valley for this geographical anomaly, having observed that the river, a major tributary of the Colorado River, cut through a narrow gap in a wall of the valley, and exited through another gap. Approximately 300 million years ago, geological pressures caused underlying salt deposits to flow to where the valley is today. In the process, a viscous mass of salt was deflected upwards, forming vertical walls of salt that penetrated overlying rock strata. Over a period of 150 million years, groundwater entered the top of the dome, dissolved the salt beds beneath, collapsed the centre, and thereby created the Paradox Valley.1

Gas station at Paradox Valley, Colorado Credit: the de Bivort Lab 2

This ancient geologic phenomena produces a contemporary problem: the Dolores River picks up this salt from the valley and carries it to the Colorado River.3 In 1996, the Bureau of Reclamation created the Paradox Valley Unit—a series of “brine-withdrawal wells” along the Dolores River, and “a deep-injection well”—to decrease the flow of brine into the river.4 Every hour, the unit extracts 45 cubic metres of brine from wells, and deposits this brine 4,300 metres beneath the earth’s surface into geologic formations, to control the salinity of the water that is delivered to users in the western U.S. and Mexico.

The Paradox Valley Unit confronts a major obstacle. The unit has caused roughly 6,000 earthquakes in the past 19 years, in a region where “seismic activity had been virtually unknown”—however, most of these have been minor. More urgently, in 10 to 20 years, the injection wells will be completely filled to capacity with brine. The value of the Paradox unit cannot be overstated. If the unit stopped working altogether, a conservative estimate calculates damages of $457 million USD annually (for damage to crops, water treatment facilities, and similar disturbances). To prevent such an environmental catastrophe for the millions of people dependent on the Colorado River, officials are working on an environmental impact study to examine how they might build upon the existing infrastructure of the unit, or explore suitable alternatives.

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