There are two problematic, and intertwined constraints to the city of Valparaiso, Chile. One being it is physically stratified by wealth and the second is the frequent torment from natural disasters that regularly clear whole sectors of the city. Valparaiso is a very steep city whose hills form the backdrop to a colonial-aged town center. Its affluent citizens occupy the lowest, most horizontal terraces that make up the core of this old town. Land values are highest in this area and fall as one ascends the hills to ever greater heights. The cities economically at risk are pushed to the elevated and precipitous ridge top bands where the land becomes highly erosive and unstable. Compounding this problem is the destabilizing effect of poorly constructed homes on steep slopes. Valparaiso receives most of its annual precipitation from May-Aug during which time fatal landslides emanating from the steep hills of the city occur every year.
The city of Valparaiso stretches up over nine levels of marine terraces to a height of 450 meters above sea level. These terraces, dissected and eroded by steep ravines, can have inclinations upward of 60%. The city derives a sort of weathered beauty from the architectural forms that affix, abut and cling to these topographic edges, but these forms also pose a serious risk. The cities expansion over the past 50 years has pushed development to the limits of where growth can be considered reasonably safe to occur. As land value increases in the urban core, unplanned settlements form in the only open parts of the city, steep ravine walls. The incidence of landslide activity increases as construction ascends to ever more precarious heights, pointing to the reality that the underlying cause stems from man-made processes. These settlements made of adhoc materials, regularly ignore building code standards set by the city.
Through a colorful and artful intervention of a terracing armature, mindful of the cities poetic identity, this project puts forth a strategy to address the drivers of slope instability on Valparaiso, Chile’s precipitous ridge top bands. A framework for organizing growth and improving upon connections to the land is the pretext of this design concept. The provision of a housing infrastructure adapted from shipping containers becomes the colorful element that ties this project to place.
Bridging the Gap integrates a social and economic infrastructure by reimagining the informal settlements in ravines as a series of terrace gardens with an agricultural function. The lack of safe affordable housing would be addressed through the provision of homes adapted from cargo containers, gardens would be placed directly aside units and tended by its residents. Valparaiso remains a working port, meaning the acquisition of this material would be close at hand.
This project addresses three main drivers of hill slope instability in Valparaiso
- the destabilizing effect of poorly constructed homes on steep slopes
- the build up of pore water pressure behind structures
- the deforestation in the upper portions of the ravine
The scheme of step-down terraces made from porous gabion structures allows for water to pass through these walls without compromising their structural stability. An L-shape fitting at the base of each wall will anchor it into the slope.
Echoing the curvature of the ravine a pedestrian bridge spans the gap between hilltops joining these once separated communities. This bridge has multiple access points that dip down into the terraces it over stretches seamlessly transitioning into the land.
The ravines of Valparaiso have solemn beauty but they have become a forgotten place in the city. The deforestation of the upper portions of the ravine contribute to increased peak flows during Valparaiso’s rainy season, when an average of 369 mm falls in just four months. A revegetation strategy in the upper portions of the ravine will improve interception at the times its needed most but also act to turn the perception of the ravines from a wasted place to a place of respite. The ravines lead to a national forest reserve at the cities edge, a forest walk will wind its way through bands of arched alles that form a gateway to this special place.
The design strategy for this project is a bold one but one that seeks to educate the current and prospective residents of Valparaiso by engaging the community in the building and revegetation process. The residents of the Gap will learn the causes of hill slope instability in their region and how to avoid practices that amplify their effects.