Mapping Myanmar's Free-Flowing Rivers

Myanmar has two of the globally most intact tropical river systems - the Salween and the Irrawaddy - which are also in one of the most biodiversity-rich regions of the world. The value of thesefree-flowing rivers is of fundamental importance to the regional biodiversity, the economy of the country, and the health and wellbeing of the people of Myanmar. It can therefore be said that the integrity of the rivers in Myanmar is of global significance. Nonetheless, the Government of Myanmar (GoM) is currently considering building several dams which would put these important free-flowing rivers at risk.

In this study we assessed the connectivity of Myanmar’s rivers under two scenarios, following
the methodology in Grill et al. (2019): a) the present situation including existing dams in Myanmar and b) a potential future scenario of intensive dam development. This future dam development scenario is based on the “business as usual” scenario laid out by the Strategic Environmental Assessment (World Bank, 2018) and assumes that the 69 known proposed
large dam projects are developed. 

By combining data and methods from the global assessment with higher resolution data and knowledge from national stakeholders, we assessed the “connectivity status” of rivers and streams across Myanmar. The results show that Myanmar is a country that maintains highly connected rivers. All three large rivers in Myanmar – the Irrawaddy, its tributary, the Chindwin, and the Salween – are categorised as free-flowing rivers and total to about 4,500 km. These rivers are exceptionally productive and biologically diverse. However, it can also be seen that the early stages of dam development have significantly impacted some smaller basins or sub-basins in Myanmar, especially within the Sittaung River basin, and country wide approximately every fourth medium to long river (between 100 and 1000 km) have been affected.

The study also shows that large-scale dam development, such as planned under the “business as usual” scenario, would result in the loss of long free-flowing rivers in Myanmar. In fact, all rivers longer than 500 km would cease to remain free-flowing and a third of all medium length (100-500 km) free-flowing rivers existing today would suffer the same fate. We would also see a higher decline in the connectivity of the coastal basins, which is worrying in view of the high ecological and social importance of rivers that feed coastal ecosystems. 
Healthy rivers and estuaries have proven to be  highly important for the economy in many countries. This is especially true for Myanmar, where rivers provide critical services such as highly productive fisheries, irrigation water, aquaculture, drinking water, ecotourism or inland water transport. For example, fisheries provide approximately two thirds of animal protein consumption, or rivers deliver sediment to deltas and coastal areas which in turn ensures coastal stability, fertile agriculture, and productive coastal fisheries. 

There is an urgent imperative for concerted global and national strategies to maintain and restore free-flowing rivers around the world, given the many vital services that they provide. Our study produced a more detailed picture of what is at stake in Myanmar and in terms of impacts on connectivity at a national scale. We recommend a further assessment to identify those free-flowing rivers or river stretches that are most important to keep connected in order to maintain the most critical socio-ecological services that Myanmar’s free-flowing rivers provide. This assessment should then be used for decision-making processes such as strategic energy planning or environmental impact assessments. It can also be a basis for discussing an adequate policy to manage remaining free flowing rivers and river stretches sustainably.
 

 
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