Flash floods spawned by Typhoon Damrey killed at least four people in Thailand yesterday and hard-hit Vietnam said it had found the bodies of four of the 23 swept away in similar torrents in its northern mountains. The deaths took the known toll to at least 45 in Damrey’s rampage across the main Philippine island of Luzon, the southern Chinese island of Hainan – where the economic damage was estimated at $1.2 billion – Vietnam, Laos and northern Thailand. Despite waning after hitting land in Vietnam on Tuesday, Damrey – Khmer for elephant – was still pounding wide areas with heavy rain and a Thai official said water spilling from a breached dam threatened the northern city of Chiang Mai.

“Heavy rain broke the reservoir and the water will flow into Chiang Mai today. Right now, the city is throwing up walls of sand bags,” said Prasert Indee, a senior official in the area. Vietnam, where nine people are known to have been killed, issued flood warnings after Damrey’s 130 kph (80 mph) winds and 5-metre (16-foot) sea surges shattered sections of the network of sea dykes protecting a key rice growing area. An official in Yen Bai province, 180 km (110 miles) northwest of Hanoi, said soldiers were searching for 19 people swept away by flash floods on Tuesday night after recovering four bodies.

The area in Vietnam most likely to suffer floods was the province of Ninh Binh, 90 km (55 miles) south of Hanoi, the government’s Committee for Flood and Storm Prevention said. The lashing rains Damrey brought were swelling rivers very quickly and it ordered five other northern provinces to reinforce dykes yet further. The rains also struck Laos, where the government said it had no immediate reports of major damage.

“We’ve had heavy rain all night and we are monitoring the flooding situation closely, but there is nothing major so far. Just some roofing gone,” Lao government spokesman Yong Chanhthalansy said. Vietnam’s dyke system, built to withstand strong gales and protect rice fields in the north, buckled under the power of winds and sea surges. Sections crumpled in four provinces, power supplies and telecommunications were hit and thousands of homes swamped, state television said. The government said at least 180,000 ha (445,000 acres) of rice in seven provinces were damaged.

But the typhoon did not hit the Central Highlands coffee belt further to the south and had no impact on crude oil output as Vietnam’s offshore rigs are well to the south. The government said in a statement read out on national television on Tuesday it was rushing emergency food and supplies to devastated areas to which 330,000 evacuees returned only to find homes and rice fields under water. Nguyen Thi Nguyet, general secretary of the Vietnam Food Association, said the government was expected to take food relief from national reserves and would have no impact on exports. “Rice from the region’s warehouses can be used to meet the food demand,” she told Reuters. “Besides, the region is also harvesting a crop with higher yields this year”. The northern region incorporating the Red River Delta is Vietnam’s second-largest rice growing area after the Mekong Delta in the south.

It produces about 36 percent of Vietnam’s rice, which is used mainly for domestic consumption, and shrimp and fish farms in the area also suffered typhoon damage. But the disruption to production in flooded areas will reduce supplies of vegetables and seafood to regional markets, including Hanoi, home to 3 million people where prices have already started rising.