Land use at the watershed scale: restrictive factors or opportunities for environmental rehabilitation? Case study in Buenos Aires, Argentina

LAFFLITTO CRISTINA MARIANA; ZULETA GUSTAVO ADOLFO; SCHELL DIEGO; GUIDA JOHNSON BÁRBARA

Mérida

Congreso; 4th World Conference on Ecological Restoration; 2011

Society for Ecological Restoration

Buenos Aires, one of the worlds 27 megacities, is located in one of the most contaminated watersheds: the Matanza-Riachuelo (200.000 ha). Land uses are highly heterogeneous and unevenly distributed, and there is an increasing transformation of semi-natural remnants to urban use. Under this scenario, we assessed different land uses in order to determine which constrain ecological rehabilitation and which require restoration. We classified, by visual interpretation, a 2010 Landsat satellite image to obtain a land cover/land use map, and perform GIS analyses to generate an impervious surface map. Based on these data, an environmental quality map was developed. Currently, 57% of the watershed is under rural use and 39% is occupied by urban and mining activities, while only 4% remains natural but degraded. The original ecosystem has been transformed completely and 20% of the area is now impervious, which is the maximum value possible for proper functioning of any watershed. In addition, 10% of the area has impervious surface values higher than 60%, exceeding the threshold for environmental quality. Based on these results, areas where restoration would be feasible are quarries, brick kilns and green spaces (5.000 ha). The peri-urban area (17.000 ha) is an important interface since it provides opportunities for rehabilitation, mitigation and/or conservation. Other land uses such as urban, industrial, suburban and roads were restrictive. Pastures have an intermediate feasibility for rehabilitation or conservation. We discuss the contribution of these findings to propose land planning and environmental zoning of the watershed, as well as the stakeholders involvement.