Salt intrusion in the Mekong Delta and a systems perspective for climate adaptation in deltas worldwide

Deltas worldwide suffer from very similar hazards such as elevation loss, fluvial sediment decline, river bed, bank and coastal erosion, flooding or drought, salt intrusion, biodiversity decline, hydrological regime shifts, leading in return to various socio-economic impacts. Yet, they are extremely complex and fundamental to the livelihood of more than half a billion people. They also often host mega-cities, thanks to their access to open seas and fertile soil for food production. Mekong Delta is not an exception. Specifically, in the past two decades it has been largely impacted by increased trends of salt intrusion. When studying salt intrusion in the Mekong Delta, we could identify a very wide range of drivers from all the way upstream in the basin to the coastal seas. Some of them are driven by climate change, and some by human intervention. Looking at the past trends and future projection when combining all the drivers of change, we see that anthropogenic drivers dominate those dynamics in the first half of the century while in the second half of the century perhaps climate change becomes the dominant driver of change. 

The Mekong Delta is exemplar of the challenges many deltas face today worldwide. But, when studying them collectively, we can identify common drivers of biophysical change across a range of spatial and temporal scales. When mapping these drivers at various scales and linking them to their direct and indirect biophysical and societal impacts we can develop a more clear systems understanding as a very important step in the adaptation planning. Furthermore, this framework can help facilitating dialogue among various stakeholders, and simplify a more critical thinking for policy makers, public and technical sectors. This system understanding of a delta from its source to its sink, is a critical first step in effective and sustainable adaptation planning, while it often gets less resources associated than it deserves.