Unesco's international experts have expressed concern about the stability of the monuments, foundations and decorative works in the historic city of Ayutthaya, which were hit hard by the worst flooding in decades.
Tim Curtis, chief of Unesco’ Bangkok culture unit, said there is a need to closely monitor the condition of the sites and the affected monuments, especially in the next few months after the foundations and structures dry out and over the long term.
The entire island of historic Ayutthaya and its surrounding area was under water for over a month starting on October 4. In some areas, the floodwaters were about three metres deep. While the water has receded in the inner island, a number of monuments in the outer periphery remain flooded. More than 100 historic monuments in and around the Ayutthaya World Heritage Site have been affected by floods, according to the Ministry of Culture’s Department of Fine Arts.
At the request of the Thai government, the first official international expert mission to Thailand on the restoration of the Ayutthaya Historical Park and cultural monuments was held last week to plan for post-flood recovery. It included damage assessment, emergency stabilisation, restoration, and planning to make the impacts less severe in the long-term.
With support from Unesco, the mission included Carlo Giantomassi, mural painting expert from Italy and Dr Zoran Vojinovic, a water management specialist from the Unesco-IHE Institute for Water Education in the Netherlands.
Giantomassi said the situation of the murals is of serious concern. They have been damaged by water and salt, and also show cracking. Due to the water being drawn up into the images, there has been capillary action with water rising from 80 centimetres to two metres high. Field testing found both sulphate and nitrate salts, which deteriorate, degrade and ultimately destroy the classic murals.
“The situation is very bad in 90 per cent of the cases, because of the humidity from the 80 cm to two metres levels and the presence of sulphate and nitrates. A great problem in Thailand is the humidity and capillarity. Every wat [temple] I visited was affected by this problem. If you don’t stop it completely, there will be a lot of damage in the future,” he said.
Vojinovic said that water management needs to be carried out at both micro- and macro- levels. The flow capacity of the waterways in Ayutthaya is approximately 1,500 cubic meters per second. As the measured inflow on October 4 was 3,300 cubic meters per second—over double the waterways’ capacity- flooding occurred.
“A combination of both structural and non-structural solutions needs to be considered; one without the other will not be sufficient,” he said.
Vojinovic also suggested that in the short-term, existing dykes can be improved or raised, canals should be dredged and portable dykes and pumps can be deployed.
In the mid-term, some of the channels can be widened, multi-purpose ponds can be built for water retention during the rainy season, and monuments can be flood-proofed, he said. In the long-term, measures may be needed to counteract the mega-scale of water, such as construction of diversion channels.
Through the assistance of the Japanese government, Yoko Futagami, a conservation specialist and Dr Tetsuo Mizuta, a flood risk management specialist, also joined the mission.
Futagami from the Japan Consortium for International Cooperation in Culture Heritage said the monuments show salt efflorescence and accumulation of salt and mud, which leads to growth of algae and scaling of the brick surface.
The field survey mission was undertaken on November 30 and December 1 at key monuments in Ayutthaya, some of which are still partly flooded, such as Pom Phet Fort and Wat Chaiwattanaram, while others are already dry, such as Wat Phra Si San Phet. A detailed assessment will be required to determine the extent of any damage. The water management experts surveyed the existing permanent and temporary waterways and water management infrastructure in the historical island and the outside area, while the mural conservation specialists inspected temples with important murals such as Wat Pradoo and Wat Puttaisawan.
The international experts worked alongside Thai specialists from the Asian Institute of Technology, Department of Public Works and Town Planning, Engineering Institute of Thailand, ICOMOS Thailand and the Association of Siamese Architects. The mission was accompanied by specialists from the Fine Arts Department and representatives of the embassies of Portugal and the United States.
“We have two issues at hand: first is the heritage conservation of Ayutthaya as a World Heritage Site in a living urban landscape; second is the flood water management issue of the whole flood plain. We need to link those two together,” concluded Curtis of Unesco Bangkok.
The historic city of Ayutthaya was inscribed on the World Heritage List in 1991. Founded circa 1350, Ayutthaya was the second Siamese capital after Sukhothai. Its remains, characterised by prang (reliquary towers) and gigantic monasteries, give an idea of its past splendour.