Flooding Spreads Across Thailand; East Region Remains Critical
Flooding persists across Thailand with the Eastern region facing critical conditions as reservoirs release water, while Bangkok's water levels recede slowly and the Chao Phraya basin requires urgent drainage efforts over the next week.
On September 28, 2025, Decharat Sukgamnerd, director of the Future Policy Center and chairman of the water situation monitoring task force for the Pheu Thai Party, updated the latest flooding situation across four zones nationwide, confirming that the Eastern region remains concerning.
Bangkok and its perimeter are experiencing slow water level declines. The Chao Phraya basin requires careful monitoring for increased water releases following high tidal periods, while the Mae Klong basin is beginning to feel effects from heavy rainfall and dam discharge. The Eastern region faces ongoing rain and multiple upstream reservoirs at or near full capacity are forced to release water. Many areas maintain water levels above one meter, with some still rising across Chanthaburi, Rayong, Prachuap Khiri Khan, Chachoengsao, and Nakhon Nayok provinces. Kaeng District in Rayong requires urgent attention regarding the Khlong Ra-Ok (Khao Chuk) reservoir, which faces embankment failure risk. Downstream residents are being evacuated urgently.
Although rainfall over Bangkok and its perimeter has decreased, water levels recede slowly. High tidal conditions persist through September 28–29. Between 11:00 and 16:00 on September 28, the Chao Phraya enters a falling tide phase, making this a critical window for accelerated drainage. Assuming no additional heavy rain, major routes should gradually reopen by September 29, though progress will be slow.
"The key remaining problem is water trapped in communities and low-lying areas, requiring sustained pumping and drainage capacity increases from streets and villages through secondary canals, main canals, into the Chao Phraya or Gulf of Thailand. We should aim to drain trapped water completely within one week," Decharat said.
Regarding the Chao Phraya basin in Ayutthaya and the Central region, current discharge from Chao Phraya Dam in Chai Nat remains below 2,000 cubic meters per second, keeping flooded areas at high water levels. Most levels are stable or rising slightly, while water above the dam continues climbing. After the tidal peak, the Royal Irrigation Department may need to increase discharge to approximately 2,100–2,200 cubic meters per second, requiring at-risk areas to prepare and have evacuation plans ready. Aid delivery to the Chao Phraya basin remains limited despite being among the first affected areas and urgently needs acceleration.
The Mae Klong basin, covering Kanchanaburi, Ratchaburi, and Samut Songkhram, began flooding on September 27 from heavy downpours. Two large dams exceeded storage capacity and must release water. The situation divides into three zones: upper reaches in Thai Mueang, Thong Pha Phum, and Sri Sawat districts in Kanchanaburi face high flooding requiring urgent assistance.
