OPERATION "HELLO EDEN"
The Pescadero-Ituango hydroelectric project is a major part of the Columbian national aim to double hydroelectric energy generation. Power from this source currently accounts for 67 percent of the national total. The Pescadero-Ituango project will add 2,400 MW of generative capacity and cost approximately $ 2.29 billion US. The dam wall is projected to reach 220 meters high and will flood an area of remote valley forest 70 km long, making a reservoir with a volume of 2,720m3. While Columbia has been gaining hydroelectric reservoirs it has also been loosing wetland habitat. The two landscape uses are here compared at the same scale.
In a hydroelectric reservoir the change in depth of water between wet and dry seasons has direct implications on the potential ecology that can develop along this changing edge. An extreme change in water elevation in a reservoir, called the drawdown, results in an inhibitory environment where very few of only the hardiest species can survive. This environment would be totally submerged for the wet season and completely without water during the dry season.
The photo below shows a similar ecological condition to that which the proposed Pescadero-Ituango Hydroelectric reservoir is expected to realize. This is a photo taken in 2008 of the Alberto Lleras Dam built in 1989. The photo clearly shows the extent of the drawdown and a landscape devoid of vegetation on all slope aspects. The shallow sloped edge zone could be contoured to support an anthropogenic wetland where water would be held in depressions.
The current edge of the future reservoir is a diverse and contiguous forest community. It lies within the Cauca Valley dry forest ecozone surrounded by the Cauca Valley montane forest ecozone - both of which have a conservation status of critical / endangered. In this area nearly 90 percent of all wetlands have disappeared. The Pescadero-Ituango hydroelectric project is set to inundate a vast area of this mountain valley in water. Along the edge of the reservoir an inhibitory environment will be produced; eutrophic and with limited biodiversity. The even topography, previously a forested mountain valley, has limited features to hold water and establish a diversity of habitats. The remote area would be ideally suited to have rapid topographic manipulation.
Four sequential bombing runs deploying stick of nine 500 lbs INS guided munitions are triggered to detonate at either 3.0 meter (B05) or 4.5 meters (B06) below ground creating a random array of deep and more shallow craters. The bombing runs are arranged to focus their detonations along the edge of the high water level of the reservoir and are targeted with higher density at a topographic location with greater overland runoff.
In the newly formed crater vegetation distributes itself according to different hydraulic regimes – levels of inundation. The crater profile creates a micro oasis of a variety of different habitats. The shallow burial blast forms an apparent crater with a plastic zone that seals the water in the depression.
Fionn Byrne, “Operation: ‘Hello Eden’,” in Neeraj Bhatih & Lola Sheppard (eds) Goes Soft: Bracket 2, (New York: Actar, 2013): 122 – 129.
FIONN BYRNE LANDSCAPE ARCHITECTURE