Thai authorities have rushed to protect parts of Bangkok from flood waters that have already inundated 70,000 homes and killed six people in the country’s northern and central provinces.

Tropical Storm Dianmu has caused flooding in 30 provinces, with the kingdom’s central region the worst hit, the Thai Disaster Prevention and Mitigation Department said.

The level of the Chao Phraya River – which snakes through Bangkok after winding almost 250 miles (400km) from the north – is steadily rising as authorities release water from dams further upstream.

Soldiers on Tuesday set up barriers and sandbags to protect archaeological ruins and landmarks as well as neighbourhoods in the old royal capital Ayutthaya, about 40 miles north of Bangkok.

There are hopes Bangkok can avoid a repeat of the catastrophic 2011 monsoon season, when it experienced its worst flooding in decades – a fifth of the city was under water and more than 500 people died.

The Bangkok Metropolitan Administration said it was monitoring the Chao Phraya’s water level and had water pumps and sandbags ready.

“We will give people a warning if there is a sign the water level is rising and if there is a risk of flash floods,” the Bangkok governor, Aswin Kwanmuang, said.

City officials have begun piling sandbags outside banks and other businesses near a canal in Thonglor, a shopping district and residential area popular with emigrants.

Once known as the Venice of the East, the capital is built on former marshland and rests about 1.5 metres (5ft) above sea level.

In the past, farmland and rice paddies in low-lying areas absorbed flood water but the city’s expansion has led much converted to real estate.

The city’s flood prevention masterplan, involving underground reservoirs and tunnels, has not been fully built because of problems acquiring land, according to local media.

At the weekend emergency teams staged dramatic rescues evacuating villagers from rooftops in parts of Chaiyaphum province, north-east of the capital.