Environmental degradation and opportunities for riparian rehabilitation in a highly urbanized watershed: the Matanza-Riachuelo in Buenos Aires, Argentina

Abstract

The growth of human societies worldwide has been associated with the degradation of natural resources; in particular, freshwater ecosystems are among the most seriously threatened. Riparian restoration has received much attention due to the importance of ecological functions and ecosystem services sustained by watercourses. The objective of this paper was to assess the environmental quality of riversides in a highly urbanized watershed in the Buenos Aires metropolitan area (Argentina) in order to identify rehabilitation opportunities. We conducted a stratified random sampling of 82 sites where we recorded 33 variables regarding geomorphologic traits, vegetation attributes and anthropogenic impacts. Pristine riparian habitats are almost completely extirpated throughout the watershed and most of the streams sampled showed signs of degradation related to multiple threats. We detected a degradation pattern that follows the urban?rural gradient occurring in the watershed which enabled the definition of four types of riversides. In order to identify potential river rehabilitation alternatives in accordance with each degradation driver detected, we performed a systematic review of the literature. We identified the fluvial rehabilitation techniques implemented and we grouped them into four types of measures: passive restoration, active abiotic techniques, active biotic techniques and active social techniques. We also recognized the reported social, ecological, economic and/or political constraints which were encountered in those experiences. All possible dimensions of the potential constraints should be recognized during the planning stage of rehabilitation and then properly addressed before and during the implementation of measures in order to make the interventions successful.