BANGKOK (CNA) – When devastating floods ruined Sumroeng Sunthonsaeng’s fruit orchards in 2011, he vowed to stay on the land.
He changed the direction of his business, focussing on lucrative and prized durians, long famous in the Nonthaburi area, a neighbouring province of Bangkok.
Last year, he was eyeing a bumper crop. But in the wake of a record drought, it never materialised. Instead of premium priced fruit, he was left with leaves that looked like they’d been burnt.
“In 2019, about 80 per cent of the durian trees had blooming flowers. We forecasted about 1,500 durians,” he said. “But issues of saltwater and severe dryness meant we had to cut the fruits out or let the trees shake the flowers and fruits off, resulting in us getting less than 200 durians.”
A lack of rainfall across the entire country has left the nearby Chao Phraya river, a major artery that flows through Bangkok and into the Gulf of Thailand, running low. Sumroeng and farmers throughout the region rely on the river to nourish their crops. Instead, they were left with salty water that had rushed up from the sea.
“Since I started farming, last year was the one that had the most salt water. The salt water surged up in November. It was faster than previous years,” Sumroeng recounted.
The saltwater intrusion phenomenon is a symptom of multiple, simultaneous environmental problems. Thailand is a low lying country, which is extremely vulnerable to sea level rise driven by climate change. Combined with coastal erosion and long periods of drought, the lack of fresh water, especially in provinces close to the sea, is becoming problematic.
“It’s natural that the amount of saltwater mass intrusion depends on the fresh water that comes from the mountains. If the freshwater mass is big, it will push the salt water out,” said Assistant Professor Payom Rattanamanee, a riverine and coastal engineer at Prince of Songkla University.
“But in drought season, when the fresh water doesn’t have power, the salt water which has more density will push itself into canals and rivers more,” he said.
As a result, underground water resources have been contaminated, important river systems face serious saltwater intrusion and farmers are seeing their crops fail. Critically, some drinking water resources, including in the capital city, are turning saline.
It poses major logistical challenges to authorities charged with managing water flow: satisfying farmers in need of water for their agriculture, communities’ drinking water demands and the intensive task of flushing affected rivers in “water hammer operations”.
The effects have been devastating for rice growers in central Thailand, who were forbidden last year from using river water to irrigate their crops in the midst of the drought, with the water needed to drive the sea’s intrusion backwards.
“Every year we have to dilute the salt intrusion by allocating more water from the north of Thailand. We need more water to try and retard the salt from the sea,” Dr Somkiat Prajamwong, the secretary-general of the Office of National Water Resources told CNA.
“But last year we had a problem since we had really low water availability, starting from the beginning of the dry season. Sometimes we cannot allocate the water from the upper northern parts – it takes five to 10 days – when we know we have a problem with salt intrusion due to high waves,” he said.
Looking ahead to the upcoming dry season in Thailand in the early months of 2021, the saltwater intrusion issue is not expected to be as severe.
“In the coming dry season, we probably won’t have a problem like the last dry season. If the people know in advance the water situation, they can plan by themselves,” Somkiat said.
As a result, Sumroeng is hoping his durian trees will enjoy a better yield come harvesting time in May, but is still concerned by the changes to the environment. He is exploring underground water tapping but expectations are that the resources will be limited and likely brackish.
“We need to see what will hit our farm first. If salt water is too much and too salty, and we cannot withstand it, we will go,” he said.
Despite better rain conditions, closer to the sea, other challenges remain. Salt is not only consuming the river, but the land as well.
In the province of Samut Songkhram, an alien structure lies slightly offshore. A several kilometre-long bamboo wall made up of thousands of individual posts provides protection to the shoreline, home to a burgeoning mangrove forest.
Over the past decade, under the stewardship of 63-year-old retiree Witsoot Nuamsiri, this coastal fortress has been built and maintained.
The bamboo is frail and usually can only withstand the waves for three to four years, before needing to be replaced. It is a painstaking process.