In China the Mekong River is called the Lancang River. For some years I’ve been concerned about dam construction on the upper part of the Mekong that flows through China.
International Rivers advises that Seven megadams have already been built, and over 20 more are under construction or being planned in Yunnan, Tibet and Qinghai. See the Google Map prepared by International Rivers. .
According to International Rivers these existing dams and those under consideration scheme will drastically change the river’s natural flood-drought cycle and block the transport of sediment, affecting ecosystems and the livelihoods of millions living downstream in Burma, Thailand, Laos, Cambodia and Vietnam. Impacts to water levels and fisheries have already been recorded along the Thai-Lao border.
If it were to end there there might be some consolation in containment but 133 more are either under construction or planned for the Lower Mekong River Basin.
This map from Z.K.Rubin, G.M. Kondolf and P.C.Carling’s publication Anticipated Geomorphic Impacts From Mekong Basin Dam Construction paints a grave picture.
Sediments and the ENSO Cycle
While my concerns have always been related to the resulting water shortages Rubin, Kondolf and Carling remind us that damming rivers also contains and reduces the transmission of sediments through water catchments. This is important because sediments, deposited along water catchments, particularly in the lower reaches where extensive flood plains develop, bring nutrients and the very substances of alluvial soils. Without flooding and deposition of sediments agriculture must rely more on chemical fertilisers.
Most deposition is likely to occur in the Normal and La Nina phases of the ENSO Cycle but if dams prevent this unless they are constructed to allow the passage of sediments. Even if they are, the retention of water will curb natural flows. So this broadens the picture.
There is sufficient online material for any reader to follow this up, but in the April 30 Jakarta Post I noticed some more telling details under the Heading El Niño dries up Asia as its stormy sister La Nina looms in a feed from Satish Cheney from AFP, Temerloh, Malaysia. Satish observes that “Withering drought and sizzling temperatures from El Nino have caused food and water shortages and ravaged farming across Asia”
The 2015-16 El Niño
The 2015-16 El Nino, has been identified by US meteorologists as the strongest since 1997-98. It has left the Mekong River at its lowest level in decades. Satish reports that this is causing food-related unrest in the Philippines, and smothering vast regions in a months-long heat wave often topping 40 degrees Celsius.
El Niño has already severely affected the health and food security of so many families and communities across the world. I am deeply worried about rising acute malnutrition among children under five and the increase in water- and vector-borne diseases. People urgently need food, nutrition, water, sanitation and hygiene as well as health services, Mr. O’Brien added.
Regional impacts of El Niño
El Niño has already influenced rice production in Indonesia, between September and December 2015 it fell by 4.08%.
Satish quotes Le Anh Tuan, a professor of climate change at Can Tho University affirming that in the Mekong Delta up to 50% of arable land has been affected by salt-water intrusion that harms crops and can damage farmland. Such events might even become common outside El Niño years if dam construction continues. Associated with this problem more than 500,000 people are short of drinking water, while hotels, schools and hospitals are struggling to maintain clean-water supplies.
Satish goes on to summarise the Asian situation accordingly:
Neighboring Thailand and Cambodia also are suffering, with vast areas short of water and Thai rice output curbed.
In Malaysia, the extreme weather has shrunk reservoirs, dried up agricultural lands, forced water rationing in. some areas, and caused repeated school closures as a health precaution.
In India, about 330 million people are at risk from water shortages and crop damage, the government said recently, and blazing temperatures have been blamed for scores of heatstroke deaths and dead livestock.
Authorities in Palau warned recently the tiny Pacific island nation could completely dry up soon in a “total water outage”.
The OCHA has prepared this interesting infographic on the situation in the Philippines.
Global response
Mr. O’Brien emphasises that the World Humanitarian Summit, to be convened by the UN Secretary-General in Istanbul in a month’s time, on 23 and 24 May, provides a critical opportunity for the international community to change the way it manages climatic risks, including future El Niño and La Niña events.
Russell Darnley Blog 
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