Exploring the Vu Gia Thu Bon River Basin

To understand the impacts of droughts and water management decisions on households in the Vu Gia-Thu Bon River basin in Central Vietnam a team of researchers from IWP and DISED made a field visit to the DakMi4 hydropower plant in the basin. On the way to the dam, which is located about 150 km upstream, they stopped to look at farming households and talk to farmers about their drought experiences.

The study looks at drought indicators: how to measure droughts from the socioeconomic perspective rather than from hydro-meteorological perspective. So how to measure the impacts of droughts on people rather than measure a lack of rain or lack of water in the river. This can help governments to better manage water shortages during drought events.

The Vu Gia river flows into the sea at Danang city. The water here is brackish, but further upstream water is pumped from the river for the city’s water supply.

High-altitude view over river and city

 

The downstream delta is intensively used for rice farming using large irrigation schemes with reservoirs and river pumps. More upstream in the delta rice farming is possible by making use of small reservoirs and irrigation systems. These farmers have in general constant harvests and have a rather reliable water supply.

Three people talking to a Vietnamese farmer standing in a rice field

 

Even more upstream, at the foothills of the Truong Son mountain range, the river bed widens before it enters the delta. Farmers grow vegetables on the banks of the river, which are often flooded during the rainy season. In absence of irrigation systems, the farmers depend on sufficient rain for a good crop. Depending on the weather, they will see good and bad years.

Four people talking in a maize field in Vietnam.

 

The Dak Mi 4 hydropower dam is built and operated by a private company and started operating in 2012. It provides power to the national powergrid of Vietnam. It was built in a remote location, which now has good access roads.

Road over the Dak Mi 4 hydropower dam

 

The DakMi4 hydropower dam blocks the water in the Vu Gia river and diverts in to the Thu Bon river. This leaves a large stretch of the river virtually dry and has large impacts downstream on water availability.

A nearly dry river bed viewed from the dam

 

Inside the power house, two generators produce 190 MW of electricity 24/7.

Two blue turbines in a hydropower plant

 

The field visit identified different ways of farming related to water supply in the upstream, midstream and downstream areas of the basin. In addition, the impacts of the diversion by the hydropower dam were better understood.

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