Ms Yingluck on Sunday led a delegation to inspect the Krapor Yai sluice gate in the province's Kabin Buri district, which has been ravaged by floods.
The delegation included Chartthaipattana Party chief adviser Banharn Silpa-archa and Hydro and Agro Informatics Institute director Royol Chitradon.
Ms Yingluck said she had asked officials to install more water pumps at the sluice gate to accelerate drainage of floodwater into the Prachin Buri and Bang Pakong rivers.
She also ordered local authorities to provide assistance to residents in flood-hit areas and open kitchens to help feed affected locals.
Meanwhile, severe Typhoon Wutip, the 21st storm of the typhoon season, is expected to make landfall over Vietnam Monday, China's official Xinhua News Agency reported.
The forecasting centre issued the yellow wave alert Saturday, warning waves as high as 10 metres may occur in the South China Sea.
After it makes landfall, Wutip (Cantonese for ``butterfly'') will weaken, but is expected to be a tropical depression when it moves into the upper Northeast. Heavy rainfall is likely throughout the entire upper half of Thailand, including most of the central plains area.
"On Monday afternoon, rain is expected in the eastern Northeast," the Thai Meteorological Department warned Sunday night. Wutip "is expected to bring isolated heavy rain and winds over the eastern and upper Northeast and the eastern North. [Affected] provinces include Nakhon Phanom, Mukdahan, Kalasin, Nong Khai, Bueng Kan, Sakon Nakhon, Udon Thani, Nong Bua Lamphu, Loei, Khon Kaen, Chaiyaphum, Phitsanulok and Phetchabun."
For Bangkok on Monday: "Very cloudy with 70% chance of rain."
The prime minister has assigned the Water and Flood Management Commission (WFMC) and the Royal Irrigation Department to survey areas that could be used to retain floodwater or dig drainage canals.
Mr Banharn said the Bang Pakong River still had the capacity to hold more water. He expected the flooding would ease within seven days if there was no heavy rain.
Prachin Buri governor Jittra Promchutima said the Prachin Buri River was the only waterway in the province used for flood drainage. The river passes Kabin Buri, Si Maha Phot, Muang and Bang Sang districts.
The province has been badly hit by flooding, as more water continued flowing in from neighbouring Sa Kaeo.
Persistent downpours since Sept 19 have caused water levels in the Prachin Buri River and its tributaries to rise sharply and inundate communities near the old market, Mr Jittra said.
On Friday, the river's height had climbed to a record 11.81 metres, 3.31m above sea level. The previous record was 11.7 metres in 1990, the governor said.
Flooding has hit 363 villages in seven districts of the province, affecting about 12,000 households, nearly 95,000 rai of agricultural land and more than 600 fish farm ponds. The flooding has also affected 78,000 head of livestock. It has damaged 311 roads, six bridges, 36 temples and 42 schools. Two deaths have been confirmed.
Deputy Prime Minister Plodprasop Suraswadi, also chairman of the WFMC, said about 200 million cubic metres of water had been drained out of Prachin Buri. Another 800 million cu/m remained, he added
Royal Irrigation Department chief Lertworoj Kowattana said an average of 70 million cu/m could be drained into the river per day.
In Sukhothai, farmers in flood-hit Sawankhalok district threatened to blockade the provincial airport unless authorities open local floodways.
More than 6,000 rai of paddy fields in several villages in the district have been inundated.
Farmer Chamniang Srisawat, 41, said the airport had built flood embankments to protect its area from flooding, blocking natural floodways.
She called on airport authorities to urgently open floodways to alleviate the hardship of affected farmers.