Catchment description

The Ca River basin is a transboundary river basin shared between Laos and Vietnam.

Key characteristics

  • Area - 31,000 km2
  • Population 3.4 million (2005)
  • The river runs northwest – southeast through the three Vietnamese provinces of Thanh Hoa, Nghe An and Ha Tinh before flowing out into the ocean.
  • Land cover - Forests 60%, Agriculture 21%
  • Average annual precipitation 1570 mm, Upstream rainy season May to October, downstream August to November
  • Average annual temperature 26.5 ℃
  • The floods during monsoon season contributes 55-75% of the annual flow (Link)

Existing water use - Farmers commonly plant rice in a double cropping pattern during a year. Three water reservoirs (Ban Ve, Khe Bo and Hu Voc Mau) have already been built to supply water for agriculture, urban areas flood control and hydropower generation. For the baseline period of 15 years (2001-2015), the average agricultural yield was 2929 kg/ha. Also, the average urban water demand coverage (supply) was about 97% and 717 gigawatt-hour hydropower energy was generated.

Key Water management problem - Irrigation demand is not always completely met and irrigation deficits lead to crop yield reductions.


In this game, you, the player, will make development decisions for a river basin. You play the role of a water resources manager. Your task is to make decisions for the next 15 years that are good for multiple sectors: agriculture, urban water supply, hydropower, environment, and flood management. The decisions you make will be evaluated under 3 climates reflecting climate uncertainty: current climate, dry climate and wet climate.

You know that there has not been enough water to maximize agricultural yields (mostly rice) in this basin.
Can new dams provide more water for agriculture, enabling a third rice crop? Perhaps dam operation could be changed to favor a particular sector. Perhaps increasing the water capacity of canals could help deliver more water.

You can try out these decisions, in each of 5 trials of this game. The schematic below gives you a general idea of the layout of the basin. In each trial, make your choices in the panel to the right, and click 'Submit'.

The model will take your inputs, and run on the server. It will take about 2 minutes to run each trial. Results will be presented for each trial. You can compare your development decisions and results from each trial.

The baseline (the past) has a score of 0. If you get a score:

  • above 0, you have done better than the past;
  • less than 0, you have done worse than the past;
  • equal to 0, you have performed neither better nor worse than the past.

Basin development choices

Dam construction

The site of three potential new dams is shown on the left, in the schematic. Click on the blue marker and select yes/no to switch on/off.

  • These dams would provide water for urban and agricultural supply.
  • No new hydropower is planned for these dams.
  • Building new dams will have negative ecological consequences. In this game, habitat fragmentation is included and scored as follows. Ngan Truoi would result in a penalty of -0.3 points; Thac Muoi at -0.6 points, and Ban Mong at -2.1 points.

Among the existing dams, note that only Ban Ve has hydropower generation. Its 'normal' operation equally prioritizes water for hydropower with urban and agricultural supply

Dam operation
Third crop
Increasing irrigation capacity