Thailand Braces for Heavy Rain as Dams Reach 71% Capacity
Thailand's dams have reached 71% capacity as the Irrigation Department prepares for heavy monsoon rains, with authorities coordinating water management to build reserves for the dry season ahead.
The Royal Irrigation Department has warned of heavy rainfall as major dams across Thailand accumulate water to 71% capacity, with plans to build reserves for the upcoming dry season. Director-General Withaya Kaeomai stated after a water situation assessment meeting that the department continues to closely monitor weather and water levels to evaluate trends and coordinate water management strategies by region. According to the Meteorological Department, monsoon troughs are currently passing through the upper south, east, and lower northeast, entering a deep low-pressure system over central Vietnam. The moderate southwestern monsoon continues to affect the lower Andaman Sea, lower south, and lower Gulf of Thailand, resulting in heavy to very heavy rain in the northeast and east regions, and heavy rain in scattered areas of the north, central, and south. Authorities remain alert for areas at risk of sustained heavy and accumulated rainfall. The highest rainfall recorded in the past 24 hours was primarily in the south, with Ban Tai in Koh Phangan District, Surat Thani Province recording 111.5 millimeters, followed by Mueang Mueang in Pattani Province at 95 millimeters, and Khao Phanom in Krabi Province at 94 millimeters. The irrigation department continues to monitor areas experiencing heavy rain and accumulation, particularly low-lying areas and those with existing water buildup, to prepare appropriate water management responses.
Regarding water levels in large and medium-sized reservoirs nationwide as of September 14, 2026, total water volume stands at approximately 54,000 million cubic meters, or 71% of combined capacity, with the ability to receive over 22,000 million cubic meters more. The four major dams in the Chao Phraya River Basin—Bhumibol, Sirikit, Khwae Noi Bamrung Daen, and Pasak Chonlasit—hold 16,000 million cubic meters combined, or 65% of capacity, and can still accommodate over 8,000 million cubic meters. Based on water level projections, nationwide reservoirs are forecast to hold approximately 61,064 million cubic meters by November 1, 2026, or 80% of total capacity, which is lower than the corresponding period last year due to El Niño effects reducing rainfall about 10% below normal, particularly in the east and eastern south regions.
The irrigation department has established a careful water management plan, closely and continuously monitoring weather and water conditions while adjusting management to match available water and regional demand. Preparations include readying water retention areas for late monsoon season and maximizing reservoir storage for dry season reserves, prioritizing domestic consumption first, followed by ecosystem maintenance, agriculture, and industry. Current water flow through major monitoring stations nationwide remains at normal to below-bank levels, with the department maintaining close oversight to keep reservoirs at optimal levels. In the Eastern Economic Corridor region, reservoir volumes currently total approximately 460 million cubic meters, or 61% of combined capacity, with management coordinated accordingly.
