Academics have complained, however, that the approval was unfair because the new Navigation in Thai Waters Act, which comes into effect next month, would crack down on illegal waterway encroachment nationwide. They added that the promenade would narrow the river and disrupt water drainage and navigation.

The new act forbids structures such as houses, piers and promenades, which will affect millions of people.

Threat to sue

Taiwut Khankaew, director of the BMA’s Building Control Division, said the Chao Phraya promenade project had been authorised by all relevant agencies, including the Marine Department, and the BMA was in the process of assessing its budget before opening to contractor bidding.

“This project is part of the government policy to open access to the river for all of the people. The project has passed all necessary procedures such as the Environmental Impact Assessment [EIA] and public hearings and received the permission to use the public land from all relevant agencies,” Taiwut said.

“We have all the permissions to build the promenade now. We just need to find a contractor in the bidding process next month and start construction in August. There is no reason to slow down the project.”

However, city planning expert Paranee Sawasdirak said it would be unjust if the project goes ahead while people’s houses and piers on the river have to be dismantled in line with the new Navigation in Thai Waters Act, because the government’s promenade project would also encroach on the waterway.

“The government stated that this project aims to reform the riverside land management and prevent river encroachment, but the government does the opposite thing and builds the promenade over the river and they encroach on the river themselves,” Paranee said.

“If the government carries on with this unfair law enforcement on people and finds exemptions in the same law to benefit their project, we will have no alternative but to sue authorities through the Administrative Court.”

Sitang Pilailar, a lecturer at the Water Resources Engineering Department Kasetsart University, also cautioned that the project would have a great impact on water drainage, especially during the flood season, and increase the chance of bigger floods in the Bangkok metropolitan area.

“From the engineering point of view, there is no limitation to build any structure. However, in reality we must consider the impacts of what we build. Even though this project has already passed its EIA, the EIA studied the project for only seven months and did not explore the impact of the promenade in the worst-case situation for flooding,” Sitang said.

She said that when she tested a model of the project on a computer she found that the Bangkok area would be at greater risk if the city faces a flood situation like in 2011.

“We cannot exactly predict how great a flood situation will be when we have the promenade over the river, when if the water volume in the river reaches the level of 3,000 to 4,000 cubic metres per second,” she said.

“There is a slim chance that Bangkok will face a big flood like 2011 again, but large structures on the waterway like this means a higher chance of a more severe disaster.”