Urban River Interventions in São Paulo Municipality (Brazil): The Challenge of Ensuring Justice in Sociotechnical Transitions

The paper aims to discuss the sociotechnical transitions regarding urban rivers policy in São Paulo Municipality by focusing on programs and projects conducted since 2000. Accordingly, we use a theoretical reflection on sociotechnical transitions and just transitions in interventions related to water and cities. Our work is based on a documental analysis of programs and projects for urban rivers in the municipality conducted via theoretical discussion. The primary focus is on the current sociotechnical regime, the channeling of streams and construction of road systems on its banks, and disputes and pressures brought by the technological landscape and niches, which lead to the construction of linear parks and leisure areas along with the bodies of water. It also shows how the issue of justice has been losing ground in this transition, which although is “in the making,” already presents many factors of injustice. This is due to the low presence of the theme of precarious settlements, in innovative speeches and practices, and the different treatment given by the programs and projects for rivers in the consolidated middle- and upper-class regions and for those located on the peripheries.

Process evaluation of urban river replenished with reclaimed water from a wastewater treatment plant based on the risk of algal bloom and comprehensive acute toxicity

Municipal wastewater reuse has an important role to play with scarce water resources and serious water pollution. However, the impact of reclaimed water on the aquatic ecology and organisms of the receiving water needs to be assessed. This study investigated one ecological restoration project of an urban river replenished with reclaimed water, and evaluated the risk of algal bloom and acute biological toxicity in the river. Results showed that the concentrations of permanganate index and ammonia nitrogen in the river could stably remain below the standard values, the concentrations of total phosphorus were high and most of the monitoring values were between 0.42 and 0.86 mg/L. The content of chlorophyll a was relatively lower, ranging from 0.06 to 0.10 mg/m3. The maximum value of Fv/Fm was 0.42, which was lower than the algal bloom prediction threshold of 0.63. Moreover, the results of luminescence inhibition rate on luminescent bacteria showed that the reclaimed water did not cause significant biological toxicity to the aquatic ecology. The study suggested that implementing urban reclaimed water reuse projects requires a series of ecological purification and restoration technologies in the receiving water, which can effectively guarantee the stability of water quality and the safety of water ecological environment.

Putting the “Beaver” Back in Beverley Brook: Rapid Shifts in Community Composition Following the Restoration of a Degraded Urban River

Widespread habitat degradation has caused dramatic declines in aquatic biodiversity. Reconfiguring channels and adding physical structures to rivers has become common practice in order to reinstate natural processes and restore biodiversity. However, the effectiveness of such measures is often questioned, especially in urban settings where overriding factors (e.g., water quality) might constrain biotic responses to increased habitat heterogeneity. We monitored invertebrate and fish communities before and up to five years after extensive restoration of Beverley Brook, a small, urban river flowing through a Royal Park in London, UK. Total invertebrate density was 5–148% higher with restoration across the monitoring period, and there was an increase in evenness but not invertebrate richness. Riverflies (Ephmemeroptera and Trichoptera) and crustaceans (Amphipoda, Asellidae) showed marked increases in density with restoration, suggesting improved flow, enhanced water quality, and greater quantity of basal resources. Fish biomass increased by 282% with restoration as did fish richness and the average body mass of three common fish species. Our results provide evidence for the effectiveness of common restoration methods in increasing standing stocks across trophic levels, from basal resources to apex predators. However, we primarily observed changes in the density of existing taxa rather than the development of novel assemblages, suggesting that large-scale factors, such as water quality and the lack of adequate source populations, might be important for understanding changes in biodiversity following river restoration.