The new face of large dams in the 21st century

Abstract

Alerted by worsening water insecurity and increasing energy demand, countries, mainly in the Global South, are building dams of unprecedented magnitude. Hundreds of large dams (≥ 100 metres) have been constructed since 2000, with hundreds more under construction. Analysing the physical attributes of these dams presents a concerning image. While these dams create expansive reservoirs with larger surface areas, their storage capacity/volume is limited: they have inefficient surface area-to-volume ratios ('S2VR'). The unprecedented size of these dams, along with the expansive surface area of their reservoirs, indicates severe environmental costs. These costs include damaging river ecosystems, mainly through ecological disturbances to the aquatic ecosystem; and greenhouse gas emissions (GHG). Other ecological costs that come with the larger S2VR include a problematic high evaporation rate and compromising the biodiversity of a wider area. Thus, the safety and environmental aspects of these ecologically damaging and unsustainable large dams should be robustly scrutinised.