Officials also dredged canals and waterways for fast flood drainage into the Mekong River, which is rising but still four metres below its banks.
The Kalasin Provincial Irrigation Office instructed communities around five rising reservoirs - out of the province's 18 medium-sized reservoirs - to brace for possible flooding.
They were Huai Pho, Huai Sithon in Muang district, Huai Sathod in Huay Phung district, Huai Sang Khieb in Somdet district and Huai Mano in Na Khoo district.
The office also placed another six reservoirs, now at between 75-100 per cent of capacity, on close watch.
Officials will release water from these reservoirs, along with four other sites, in response to rainfall resulting from Sonca while 30 large water pumps have been prepared if required to aid affected residents, said Kalasin irrigation project head Anatasak Yaemcheun.
According to the Meteorological Department's ninth warning on Sonca issued on Tuesday, Sonca, which has winds of up to 65 kilometres per hour, is expected to make landfall over Hue, Vietnam, on Tuesday.
It will then be downgraded to tropical depression over Laos and then to a low pressure cell when it reaches Northeast Thailand, bringing a lot of rain with isolated heavy to very heavy rain. The North, Central region and the East will also be affected, the department said.
People should be beware of severe weather conditions that could cause possible flash floods until Friday, the department said.