Central Vietnam floods cut highways and suspend Ly Son ferry links

Two days of heavy rain have flooded around 20 homes in mountainous Da Nang and cut National Highways 40B and 24C, severing the main road links between mountain communities in the former Nam Tra My District and the route toward Quang Ngai. For carriers and forwarders moving cargo through central Vietnam this week, that's the operative fact: the inland legs are broken.

In Tra My Commune, the Truong River overflowed and pushed water more than one meter deep inside many houses by Wednesday morning, local authorities said. Landslides and flooding also cut off several roads in Tra Leng, Tra Tan and Tra Giap Communes. Local traffic, not long-haul freight, bears the immediate brunt — but blocked mountain highways mean collection and distribution in the region stops until crews clear them.

What does the flooding do to hydropower and river levels?

The rainfall has dumped enormous volumes into upstream hydropower reservoirs. At 7:00 am, inflows into the Dak Mi 4 reservoir exceeded 1,948 cubic meters per second — roughly the flow of a mid-sized river — lifting its water level by around 12 meters in a single day. Song Tranh 2 saw inflows nearly triple in six hours, from 1,556.59 cubic meters per second at 1:00 am to 4,395.44 at 7:00 am.

Those numbers matter downstream. Reservoir operators facing that kind of inflow either store it under stress or release it, and either choice shapes river behavior for communities and crossings below the dams.

How much rain, and where?

Quang Ngai Province recorded 545.2mm in Tra Thanh and 487mm in Son Long over 24 hours, with more than 400mm in several other mountainous areas, according to the provincial weather agency. To put that in perspective: 545mm in a day is more than double what many temperate cities receive in an entire year.

Forecasters expected a further 70-120mm across eastern Quang Ngai on Wednesday, with some areas due over 180mm. Rising rivers have heightened concerns over flooding, flash floods and landslides.

Evacuations and severed crossings

Authorities have evacuated hundreds of residents from landslide-prone communities:

• Nearly 60 people in Ba Vi Commune
• 40 in Ba Xa, after a large crack appeared on a mountainside
• 100 in Ngoc Linh

Floodwaters submerged several roads and low-water crossings, including the Thach Nham crossing and Provincial Road 676 through Mang But Commune. Rough seas with waves of 2-3 meters prompted the temporary suspension of ferry services between Ly Son Island and Sa Ky Port — a small but concrete logistics disruption, stranding island freight and passengers until conditions ease.

Gia Lai: blocked streets and a river nearing alert level

In eastern Gia Lai, formerly Binh Dinh Province, overnight rain delivered 100-120mm to localities including Van Canh, An Vinh, Hoai Nhon Bac and Quy Nhon Tay. Rising water on the Ha Thanh River submerged several low-water crossings in Quy Nhon Dong Ward, and police blocked a flooded crossing on Dien Bien Phu Street early Wednesday to prevent accidents.

In Tuy Phuoc Commune, authorities cordoned off two temporary bridges and inspected flood-prone areas. The provincial Department of Agriculture and Environment warned the Ha Thanh River could reach or exceed its second-level flood warning threshold. The arithmetic of the situation is unforgiving: if heavy rain coincides with high tides, drainage into Thi Nai Lagoon gets restricted, and low-lying areas in Quy Nhon Bac, Quy Nhon Dong and Tuy Phuoc face heightened flooding. The Lai Giang River basin carries similar risk.

What happens next?

Authorities across the affected provinces are monitoring river levels, restricting access to dangerous roads and preparing further evacuations if necessary. The one piece of good news is chronological: heavy rainfall across the region is expected to gradually ease from Thursday. Barring fresh downpours, road clearance and a resumption of the Ly Son ferry run should follow, and inland transport in central Vietnam can start returning to normal.