Regarding the possibilities of provisional landscapes, there is a project in in the megacity of Lima, Peru that I've been keeping an eye on since visiting there last summer. Given recent developments during the Andean rainy season, it is worth revisiting right now. The Rimac River is the main river running through the megacity (which is actually the capital of Lima and the port city of Callao combined) and supplies the conurbation with its drinking water. Like Los Angeles, the capital was founded on its banks some 20 kilometers inland, according to Spanish colonial practice that was eventually codified in the Laws of the Indies. This is the historical reason many major American coastal cities are a little inland, with a different port town located on the coast, such as Long Beach/Los Angeles.
Originating from glacial melt in the Andean highlands, the river draws its name from the indigenous Quechua word for “talking”, likely because of the roaring sound it makes during summer rains when elevated water levels go crashing over the rocky riverbed. Currently, the Rimac is the subject of a megaproject organized under the Peruvian company Linea Amarilla-SAC and backed by Brazilian infrastructural giants INVEPAR and OAS. The objective is to construct an automobile tunnel underneath the riverbed through the metropolitan area. This will allow for some of the edges of the river in the city to be reconstructed as ecological, recreational riparian corridors punctuated by park zones. It is something between an underwater subway tunnel and a green roof the size of a major urban river! Compelling stuff. This past August I spent some time in Lima with my wife and had the opportunity to briefly see this project in person.
To pull this off, they have to push the river to one side while they excavate between the existing highways. To do this they have constructed a provisional wall meant to separate the river from the construction zone. There is, however, one problem. I had the opportunity to visit this project briefly this past August, and seen from a heavily trafficked pedestrian bridge, the effect was rather enchanting. The Rimac, like many rivers in the American Cordillera, is prone to seasonal floods that are massive relative to base flow (a somewhat outdate concept, but useful here) and this year's levels were nearly double those in recent years (128 m3/s versus 55 m3/s). For this situation, the engineers had a plan:
>The diversion canal (created by the wall) was designed to a capacity of 120 m3/s
>if the Rimac discharge reached 70 m3/s work would be stopped on the tunnel and workers evacuated from the tunnel zone and put to work on other portions of the project.
>If the Rimac discharged reached 115 m3/s a breach would be opened in the diversion wall and the work zone would act as a release valve.
And this is precisely what happened. In fact, it appears that the elevated water levels caused a rather spectacular and unanticipated additional breach as they surpassed the design load of the provisional wall. I love this. When I was there it was evident that this was a series of complex systems- economic, hydrological, mechanical- all being intelligently choreographed and creating a fascinating scene near the heart of downtown. Yet for all of the technique and intelligent conceptualization on display in this complicated act of construction, the river still found a way to introduce an unexpected event- the collapse of the diversion wall new the bridge with the summer rains. When you see this provisional landscape (as I did from a bridge that crosses it right near the main central plaza of Lima) you get a sense of the historical importance of the river and its accompanying infrastructural bands (rail, highway). You are also taking part in the future city which is actively forming around you. I'm reminded of something Graham Harman said, that “landscapes are minimal real anchors that link various shifting worlds“.”]
The question for landscape architecture in this study is what might we bring to this situation? The Rimac is already a fascinating landscape, and whether it becomes a successfully constructed highway tunnel or not is likely to hinge on landscape architectural expertise. Of course, landscape designers will have a major role in shaping the recreation and ecological zones that are reconstructed in the riparian zones of the river. But I wonder if we might explore the capacity of the landscape to “link various shifting worlds” through the concept of the provisional landscape? Might additional breaches in that diversion canal wall be designed to pile up sediment in certain areas, trash and other detritus in others, all with the goal of catalyzing future recreational and ecological possibilities yet with the understanding that the river has surprises for us? In segments it might live on to become part of the recreational and ecological landscape itself, not just conjure it forth. In one area it provides shade and separates ball courts, in another it deliminates and contains subsoils, allowing for special habitat creation
It seems likely that the Rimac will be redesigned according to the prevailing park paradigm. This would be an unfortunate result. The creation of public spaces for recreation and habitat are desperately needed in Lima (likely the subject of another post) but there is nothing to suggest that it need be done in the usual ways. And to do so would miss out on possibilities created by the current provisional landscape- the aesthetic affect of the technological sublime, the design of control breaches, responsibly reusing industrial materials, and respecting the ingenuity and effort that are actively making the future city possible.