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Degassing May Render Lake Nyos Safe 

By Leocadia Bongben

People living around Lake Nyos may finally start feeling safer when two degassing pipes start pumping 600,000 tons of carbon dioxide out of the lake in February, a process that is expected to run up to 2014. The two supplementary pipes worth FCFA 1 billion are presently under installation in the lake by French scientists, experts told The Post recently.

Dr. Njilah Isaac, Coordinator of Lake Nyos Project at the United Nations Development Programme, UNDP Geo-environmental scientist, holds that each of the pipes has the capacity of eliminating the carbon dioxide dissolved in the waters of the lake, four times the capacity of the lone 15cm pipe installed in 2001. This disperses 20,000 tons of carbon dioxide per year. After 10 years, deeper layer of the lake need to be degassed.

With the single degassing pipe, it was going to take approximately 30 years, by then a child born on the day of the disaster will be 50 years old. But, with the additional pipes of 25.8cm each experts say it may take about three years for the gas to be eliminated. If this is done, the lake would be safe for ever since the pipes will still be maintained there.

The pipes made of polythene, weighing 1.2 tons and are attached to a raft and sent into the lake ensuring that it remains at an upright position suspended in it, Dr. Gregory Tanyi-Leke, Geologist at the Institute of Mines and Geology, explained. Water, which is 90 percent carbon dioxide and 10 percent water, is moved up the pipe and it goes as far as 50m above the surface of the lake. By the time the water falls the carbon dioxide is diffused in the air.

Lake Nyos, a very rare example of exploding lakes, is saturated with CO2. During a Limnic eruption or Lake Overturn, CO2 erupted from the deep water as was the case in 1986 suffocating both human beings and animals, Tanyi-Leke, Geologist, at the said. More than 2000 people and 3000 heads of cattle died when this happened during the giant outburst. Prior to this, 100km South-East of Lake Nyos a similar incident occurred in Monoun in 1984 killing 37 persons. 

Meanwhile, this kind of lake with CO2 is equally found in Rwanda with the Lake Kivu, identified by the Working Group on Crater Lakes after the Nyos incident. Tanyi-Leke pointed that the eruption was a new phenomenon in science when it occurred, attributing this to why little has been done in 25 years since the disaster occurred besides financial problems.

Imminent Collapse Of Lake Dyke

Despite hopes raised with the installation of the pipes, the dyke of the lake may collapse at any time if not reinforced. It is feared that the friable pyroclastic material that hold the waters of the lake may collapse, causing floods downstream right to river Katsina Ala in Nigeria. Were the dyke to break, instability will be created in the lake causing a CO2 explosion.

A study Njilah conducted five years ago was confirmed by UN experts from the Office Charged With Humanitarian Affairs (OCHA), that the Lake  Nyos  dyke could collapse in the next 5-10 years as a result of  erosion and fracturation, causing holes in the upper layer of the lake. 
Five years later, Njilah re-affirms that the lake is unstable. "It is true the lake can collapse", he said.

However, he termed recent concerns expressed by the Nigeria media, as alarmist. The fears are that should the lake rupture, it would wash away over 200 villages in some Nigerian towns along the border. An alert system has been put in place and whenever the carbon dioxide concentration in the atmosphere rises above 0.3 percent the alarm will be triggered, the expert said.

However, the lurking fear is that should the lake dyke collapse, the stability would change and provoke an eruption up to about 28km. Going by him, the Lake Nyos Project at the UNDP/and Ministry of Territorial Administration, MINADT, has already trained and equipped the crisis and catastrophe management committee for Menchum Division to handle crises when they arise.

Reinforcing Lake Dyke

On the other hand, the lake has to be reinforced through a procedure Tanyi Leke describes as grouting-a process whereby holes are drilled on the surface slap and concrete injected to hold the dyke in place.

The European Union recently donated FCFA 6.5 billion for the reinforcement of the lake dykes and for the rehabilitation of about 4000 survivors who left the area since 1986. The Charge d’Affaires of the EU delegation, Dick Naezer, insisted on the urgency of reinforcing the lake and other works when the EU formalised the donation with the Minister of Economy Planning and Regional Development, Louis Paul Motaze recently.

However, reinforcement work is unlikely to start until February after the degassing pipes must have been installed, Tanyi-Leke confirms. But the reinforcement project is starting on a bad note as the contractors have been declared not qualified; the tender declared bad and new tenders opened. Despite efforts to render the lake safer and the dykes reinforced, rehabilitation of the survivors remains preoccupying.

In collaboration with the EU, a National Programme for the Security and Socio-Economic Integration of the Nyos area Cameroon was put in place. But, unless the security around the lake is ascertained the population cannot be rehabilitated. Equally, there are concerns raised as to the effective management of resources: fertile farm and grazing land and the provision of structural infrastructure; schools and health centers. 
 

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