Heavy to very heavy rain is forecast across Thailand from Oct. 9-13, threatening to add water to central provinces where rivers are still rising and major reservoirs are over capacity.

The Thai Meteorological Department issued a warning on Oct. 7, forecasting thundershowers, gusty winds, hail and heavy rain covering Bangkok and the central region starting Oct. 10 and the South through Oct. 13.

The department's national forecast attributes the system to a high-pressure system from China that will push the monsoon trough south. Forecasters warned that accumulated rain could cause flash floods and overflows along waterways near foothills and in lowlands.

Flooding affected 1,149,285 households, or 3,143,962 people, in 27 provinces and Bangkok as of 6 a.m. Oct. 6, the Department of Disaster Prevention and Mitigation said in a release posted by the Government Public Relations Department.

Satellite imagery from Sept. 28 to Oct. 4 showed about 5.12 million rai (about 3,160 square miles) under water across four regions, the Geo-Informatics and Space Technology Development Agency reported.

Pa Sak Jolasid Dam held 840.94 million cubic meters on Sept. 28, or 96.49 percent of capacity, the Royal Irrigation Department warned. The department scheduled staged increases in releases starting Sept. 30, reaching 400 cubic meters per second (about 14,100 cubic feet per second) by Oct. 2. The dam reached about 110 percent of normal storage by Oct. 6, the disaster agency said, Nation Thailand reported.

Office of the National Water Resources Secretary-General Chayant Muangsong said Oct. 1 the agency was accelerating drainage into the Gulf of Thailand and diverting flows into irrigation systems and harvested fields, Nation Thailand reported. Chao Phraya Dam planned to raise its discharge to 2,400 cubic meters per second (about 84,800 cubic feet per second) that day, while Bhumibol Dam suspended releases Sept. 30 to Oct. 1 and Sirikit Dam cut its discharge to 7 million cubic meters per day. Chayant warned that early-October high tides could obstruct drainage.

Prime Minister Anutin Charnvirakul ordered all provinces Oct. 1 to inventory pumps, boats and machinery for transfer between provinces, Nation Thailand reported. The disaster agency is mobilizing up to 80 water-pushing boats at the mouth of the Bang Pakong River to speed drainage from Chachoengsao and Prachin Buri provinces, Nirat said Oct. 7, Khaosod English reported.

Bangkok Gov. Chadchart Sittipunt said in June, while running for governor, that many of the city's existing drainage pipes can handle only about 60 millimeters (about 2.4 inches) of rainfall, Thairath reported. He later said the late-September storms dropped 200 to 300 millimeters (about 8 to 12 inches) of accumulated rain, Nation Thailand reported.

Bangkok recorded 487 millimeters (about 19 inches) of rain from Sept. 1-25, compared with an average of nearly 269 millimeters (about 10.6 inches) for the period, the city's Drainage and Sewerage Department reported, the Oman Observer said. "Our problem is that the canals are full," Chadchart said.

Water overtopped flood barriers along the Khlong Hok Wa Sai Lang canal on the Pathum Thani border and in Bangkok's Sai Mai, Khlong Sam Wa and Nong Chok districts Sept. 29, prompting emergency cell broadcast warnings, Khaosod English reported.

Ahead of the rainy season, the city reported clearing more than 2,980 kilometers (about 1,850 miles) of drainage pipes, nearly 78 percent of its annual target, with canal dredging more than 65 percent complete.

Chadchart said Sept. 25 that more than 200 of the city's more than 700 identified flood-risk points still need improvement, Nation Thailand reported. On Sept. 28, he called for more drainage tunnels to carry floodwater directly to the Chao Phraya River and for joint investment by the city and national government, the outlet reported.