Features

Urgent call for dam safety
by Namini Wijedasa

Experts on dam safety are sounding an urgent warning about the impact of increased human activity Ė including tourism Ė on the countryís reservoirs, stressing that at least one bund has been seriously damaged and many more may follow.

They also say that all of the countryís major and minor dams need rehabilitation and that failure to act immediately could result in catastrophe.

The issue was deemed crucial enough to deserve mention in the latest Central Bank report. The last major dam breach was in 1986, when damage to the Kantale bund caused the deaths of 127 people. Around 8,000 families were affected and vast stretches of property destroyed.

Extensive repairs

Sri Lanka has around 350 major dams and over 12,000 small dams serving irrigation, hydropower, urban domestic water and flood mitigation purposes. An additional 10,000 to 15,000 minor dams have been abandoned and need restoration. In charge of upkeep are the Mahaweli Authority, the irrigation department and provincial councils, among others. All of them find their resources drastically inadequate.

"The treasury gives us only one-fifth of our annual requirement for dam maintenance," said an irrigation department source. "We have been forced to prioritise some projects and forget others. Problems have now accumulated over the years. Our dams need major rehabilitation."

Several dams require extensive repairs. These include the Parakrama Samudraya and the Giritale tank in Polonnaruwa, and the Senanayake Samudraya in Ampara. "I can name a few dams in every district that need fast attention," the source lamented. "We will have to face the consequences in five to ten years, at the most."

He explained that the sluice gate in Senanayake Samudraya needs immediate repair but work cannot begin till September as water levels are currently too high.

Irresponsible tourism

"There is a big rush by entrepreneurs to build hotels and resorts close to water bodies and also to start water sports," added D. W. R. Weerakoon, former director general of irrigation. "We are even speaking of sea planes landing in reservoirs which were originally designed to supply water for irrigated agriculture or for domestic use. We canít impede development but we must examine how to protect these structures in the face of new activity."

"You canít just allow people to play around in these reservoirs as they wish," he continued. "If someone is interested in water sports, they must get permission subject to a scientific analysis of how the new activity impacts on the dam."

Authorities in Wellawaya confirmed that a section of the Handapanagala bund has slipped into the water, necessitating vital repairs. Irrigation officials are blaming provincial tourism authorities. In April, the Uva Provincial Council organised a New Year festival on the bund and also arranged canoe races. While it provided much-needed entertainment to the local populace, it also disturbed the hydraulics of the dam.

"This bund was not in a good condition to begin with," said another authoritative irrigation department official. "The festival simply aggravated the problem. Even the canoes, which donít have engines, had an effect. We have no power to prevent influential people from doing these things."

The damages to the Handapanagala bund have forced irrigation authorities to artificially lower the water level of the reservoir. "We were compelled to do so," the official said. "We usually preserve water for the next cultivation cycle but we had no option at Handapanagala. The farmers will suffer."

"When people start various activities within a water body, it changes the hydro dynamics of the waterway," Weerakoon explained. "This has an effect on the main dam. Anything can cause a disturbance, including inland fishing and boats."

Encroachment

Encroachment is seen as a major problem. Settlement in catchment areas has resulted in disturbance to upstream hydrology. Downstream, too, populations have increased causing interference in spillways, sluiceways and canals. However, neither irrigation nor provincial authorities have sufficient authority to deal with the dilemma.

Flood protection bunds have also been severely encroached on. One example is the Kelani river flood protection bund. "The Kelani river has two flood protection embankments, one on its left bank protecting the Colombo city and one on the right bank protecting the Kelaniya area and Gampaha district," Weerakoon pointed out. "These bunds have been very badly encroached. Settlers have constructed shanties and dwellings, sometimes cutting the earth bank to erect houses." The irrigation department once went to courts and obtained police support to evacuate the illegal residents but has found it impossible to prevent new encroachment.

The same is true of flood protection bunds on the Nilawala river, Ginganga and Kaluganga.

Are the dams safe?

Meanwhile, the irrigation department is calling for a reanalysis of the entire dam network to evaluate the safety of these structures in the face of altering topographical conditions. "Ideally, dam engineers must reanalyse conditions every ten years," said the official earlier quoted. "We design structures to suit certain conditions. These are constantly changing. We must start a comprehensive study now."

"One problem is that employees in government departments are preoccupied with other issues," he elaborated. "The irrigation department is no different. If a minister wants a circuit bungalow reserved, an employee will drop everything else and attend to that."

Systematic research is requisite to determining the extent of decay and ageing in Sri Lankaís dams. But even this survey requires experts and they have become a rare breed. The best have migrated, drawn away by greener pastures.

Replace lost expertise

"You canít prevent people from leaving the country but you must replace them," Weerakoon stressed. "We need training. Since foreign scholarships have dwindled, we must spend some money from our national budget to train our staff. Not only high-level engineers, but middle and low-level technicians."

Irrigation authorities reiterate that the reservoirs often have large settlements downstream -- therefore, itís imperative to ensure safety. The country has no modern technology to monitor and detect dam failure. This is particularly vital where earth dams are concerned.

"We still depend on timely inspections and reporting by knowledgeable people but technology is more advanced now," Weerakoon said. "We canít replace human observation, reporting and analysis but the process could be less laborious and tedious. A simple sensor can ensure 24-hour monitoring. Sri Lanka doesnít have the technology yet."

Experts emphasise that a disaster arising from damage to or failure of a dam is not unavoidable. "We are aware of the shortfalls, thereís a possibility of disaster and we must strengthen ourselves," Weerakoon maintained. "What is most desirable is that we prevent major disasters from happening.

"We must take preventive action now `85 we must stop further deterioration."

 

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