Thailand’s coastline, which is 2,667 kilometers long, is suffering severe erosion due to strong waves and winds.
One of the worst-hit sections is the 45-kilometer-long coast of Samut Prakan province. The long-running coastal erosion has cost many local families their farming and residential areas. Some families had to move away, and those that stayed have had to move their houses to higher locations.
The coastal Ban Khun Samutchine community in Tambon Laem Fa Pha subdistrict of Phra Samut Chedi district relocated five times in the past two decades. Severe erosion affects its temple, Wat Khun Samutrawat. Today the ordination hall is a meter underwater. The compound of the Buddhist temple used to cover an area of over 112,000 square meters, but only 8,000-9,000 square meters remains. It does not have a footpath anymore, so monks and local people visiting the temple used to walk on a line of water jars. Later a wooden walkway was built, but it could not withstand the strong waves. It was finally replaced with an elevated concretefootpath. Also elevated was the floor of the ordination hall, lifted one meter to escape flooding. Erosion has encroached about a kilometer deep into the mainland in the Ban Khun Samutchine community. Without effective solutions, coastal erosion may reach 1.3 km into Samut Prakan province in the next two decades.
To help the people cope with the problem, Assoc. Prof. Thanawat Jarupongsakul and associates from a unit studying disasters and area-oriented information in the Faculty of Science, Chulalongkorn University, have studied the coastal erosion in Ban Khun Samutchine village. The study project, sponsored by the Thailand Research Fund, has drawn experts in many fields, including meteorology, hydrology, coastal ecology, geological disasters, economics, coastal engineering, sociology, landscape architecture, and land legislation. Local researchers from the community also take part in the study by gathering information. By this means, they can simultaneously learn about and understand the natural processes in their locality.
The study has been built on research into coastal erosion during two monsoon seasons: the southern monsoon between March and April and the southwestern monsoon between May and September. Sediment resulting from coastal erosion is deposited near the shore, but not for long. Between November and February, northeastern winds blow the sediment into the sea. The information from the research has led to the invention of the “Khun Samutchine 49 A2” permeable breakwater.
This kind of breakwater consists of two parts. The first one comprises three rows of concrete columns in the shape of equilateral triangles. The columns in the first row, which faces the sea, are 10 meters high. The columns in the second row are eight meters high, and those in the third row, facing the shore, are six meters high. The rows are placed 1.5 meters apart from one another and the columns in the three rows are placed in a serrated formation. Waves break repeatedly when they hit the rows of triangular columns. As waves are dissipating inshore, they leave sediment behind the breakwater. The second part will be made of rows of boomerang-shaped concrete columns that will close both sides of the three rows parallel to the shore. The boomerang-shaped columns are intended to trap sediment and protect it from northeastern winds. The breakwater will therefore reduce coastal erosion and trap sediment. When there is enough sediment, the researchers will plant mangroves so that they will help trap more sediment and accelerate the reclamation of land in the area.
Assoc. Prof. Thanawat said the three rows of concrete columns had been installed for a distance of 250 meters parallel to the shore. During the installation of the columns, the researchers measure the amount of sediment, the force of the currents, and the direction and speed of the winds. The information will help them improve the final version of the Khun Samutchine 49 A2 breakwater. It is the world’s first initiative to cope with the erosion of a muddy coast. There are similar projects overseas but they are designed only for sandy shores. The installation of the three rows of concrete columns has so far produced satisfactory results; the depth of the deposited sediment has reached 30 centimeters. The experiment has succeeded in stopping coastal erosion in this fortunate area.