Bangladesh

Advertisement

 

100-year Delta Plan threat to deltaic equilibrium: experts

Emran Hossain | Published: 00:25, Feb 09,2019 | Updated: 01:49, Feb 09,2019

 
 

Bangladesh Delta Plan 2100 threatens the natural equilibrium that sustained the world’s largest delta for centuries, said geologists and hydrologists.
They warned that ecological catastrophe could occur if the plan seeking to intervene with the active delta’s natural flow of waters and the sedimentation process was implemented without removing the flaws.
But the government thinks that its delta plan would bring prosperity, food security and provide protection against natural calamities and the adverse impacts of climate change.
‘These are false promises. The plan creates a false sense of security,’ Lock Haven University, USA, geology professor Md Khalequzzaman told New Age.
‘The plan should be debated by scientists, experts and people likely to get affected by it,’ said Khaleq, who studied hydrological aspects of the plan.
The executive committee of the national economic council approved the plan in September last year and also approved 80 projects to be implemented under it spending $37 billion over the next 10 years.
Foreign and local scientists and experts while participating in an environmental conference in the capital in mid-January requested the Bangladesh government to revise the plan to remove the wrong prescriptions.
The plan divides Bangladesh into six hotspots mainly based on hydrological characteristics where massive investments were planned for building infrastructures, said Khaleq.
The hotspots are coastal zone, Barind and drought prone areas, Haor and flash flood areas, major rivers and adjoining areas, urban areas and the vChittagong hill tracts, he said.
To protect coastal zone against natural disasters and climate change impacts construction of new polders were planned alongside strengthening of the old ones, said Khaleq.
Polders enclose low-lying areas with dikes or embankments to control natural water flow into the protected areas.
‘Polders are threats to deltaic land formation,’ said Khaleq.
He explained that interruption in natural water flow means interrupting aggradations, the fundamental mechanism of delta formulation.
Over the last 11,000 years the extension of Ganges-Brahmaputra delta toward the sea could take place as aggradations kept up with sea level rise, he said.
Between 1,780 and1,980 the shoreline in the eastern region in the delta advanced by 50 miles, he said.
‘But polders would intervene with this natural system,’ said Khaleq.
He said that polder protected areas in the coastal zone already sank 1 to 1.5 m compared to areas outside the polders experiencing natural sedimentation.
‘Polder protected zone is turning into a bowl,’ said Khaleq.
In case of a breach in the polder the protected area will suffer prolonged inundation as pumping out water from there would be very difficult, he said.
Adding up to the problem is natural subsidence of soft sediment against sea level rise, he said.
The delta plan also proposes to build a cross-dam on Meghna at Urir Char for land accretion along the coast.
Khaleq said when a river gets blocked rapidly due to artificial land accretion it creates new environmental conditions.
He said that the cross dam would hamper tidal activities in Meghna to which were tied life cycle of many aquatic animals.
The area where the cross dam is planned is frequented by hilsha in its breeding season.
‘New land will rise but at the cost of entire ecosystem,’ said Khaleq.
Potential impacts of the cross dam on humans and their livelihood would have to be discovered through the struggle of coping with conditions of which they knew nothing about, he said.
Barrages are also planned across major rivers like the Ganges, called the Padma in Bangladesh, and the Jamuna, said Khaleq.
Authorities also spoke about plans of narrowing down Jamuna and concretizing its banks, said Khaleq.
‘There is no use of another barrage in the Ganges,’ said Khaleq.
He said water supplies were already very low in Padma since the Farakka barrage was built, pushing the river to its death.
With the Ganges water, also dwindled the supply of sediment, he said, which fell to one billion tonnes a year recently from two billion tonnes suspended in the Ganges waters in the 1960s.
A dam in the Padma would double the Farakka impacts, causing salinity intrusion and severe drinking water scarcity downstream, said Khaleq.
For the haor regions are planned more embankments and highways blocking natural water flows.
Khaleq said that it was more important to invest in researches to understand rainfall pattern shifting in the haor region to improve the flood forecast system before building roads there.
Geological Survey of Bangladesh director Abdul Baquee Khan Majlis said that it might not be wise to go against nature.
‘It is always better to try to adapt to nature,’ he said.
He said that Bangladesh sits on a huge natural water draining system where it may be impossible to completely control rivers through infrastructural interventions.
‘Rivers flowing through Bangladesh are powerful and they will find their ways around obstacles,’ said Baquee.
Artificial land accretion reduces the width of river forcing it to erode somewhere to carry the water supposed to be passed through it, said Baquee.
‘Swandip or parts of it may erode because of a dam in Urir char,’ he said.
‘We need to understand the limit to which we are allowed to play with the nature,’ he said.
He referred to catastrophic floods in parts of the world caused by dam failures to highlight the dangers involved in attempting control over nature through infrastructural interventions.
‘Natural floods only inundate but floods coming through breaches in dams sweep everything away,’ said Baquee.
Last month floods caused by dam failures washed away several hundred people in Brazil. Many of them were killed while others went missing without a trace.
‘Alternatives have to be weighed,’ said Baquee.
Water resource management expert professor Ainun Nishat said that technologically it was possible to implement the plan.
‘The technology is there and we need to ensure that it applies properly,’ said Ainun Nishat, who was hired by the government along with some other experts to formulate the plan.
Referring to developed countries successfully managing barrages and dams, he said, ‘Operational maintenance is crucial to implementation of the plan.’
Planning Commission member Shamsul Alam said that the plan was adopted after extensive consultations with engineers, scientists and experts working in relevant fields in the country for long.
‘A total of 26 baseline surveys were done for the plan,’ he said.
Shamsul Alam said that Bangladesh benefitted from polders for long and people wanted more polders to protect crops from disasters.
He said that the barrages were planned to preserve excessive water in rainy season for subsequent supply to salinity or drought prone areas.
‘We need to destroy to create. This is the way of the world,’ he said.

Want stories like this in your inbox?

Sign up to exclusive daily email

Advertisement

images

 

Advertisement

images