Talita Fernanda das Graças Silva

Connected reservoirs along cascade systems have been constructed along large rivers worldwide, establishing a network of aquatic environments. To date, modeling studies largely ignore the ecological feedback on water quality in connected reservoirs, thus limiting the ecosystem representation and missing the mechanisms acting between them. Here, we applied a novel modelling framework that fully links reservoir processes along the cascade system, considering the input from each water body to the next in the system. The one-dimensional GLM-AED model was applied to simulate hydrodynamics and biogeochemical processes in six reservoirs along the Tietê River (Brazil) situated in the most populous Brazilian state (24 million inhabitants), playing a relevant role for the energy generation and water supply in the region. The model was run for the 2008-2016 period, calibrated and validated against measured field data. Eighteen scenarios of reducing nutrient loads were simulated to assess how restoration strategies modify the ecological state downstream. All six reservoirs were sensitive to nutrient load reductions, which changed the nutrient retention capacity, and triggered a domino effect along the cascade system, improving the ecological conditions further downstream. It reveals that local restoration strategies devoted to the uppermost reservoir in a cascade system are propagated and amplified along the system. This finding is of primary interest to water managers since the improvements from local strategies into the uppermost reservoir, rather than site-specific, act at catchment scale.

Standardized design criteria and performance assessment of parcel-level on-site stormwater detention (OSD) remain limited. This study evaluates the hydrological impact of OSD — designed per Belo Horizonte’s (Minas Gerais, Brazil) municipal guidelines — at both parcel and catchment scales using hydrological modeling in a highly impervious, flood-prone subcatchment. Results indicate that while existing guidelines are generally effective, volume sizing could be optimized. OSD implemented across 31.8% of the catchment significantly reduced peak flows, though effectiveness varied by spatial scale. At the parcel level, outflows decreased by 72.3% for 2-year and 50.7% for 100-year return period rainfalls, with delay in peak times of 41.7%. At the catchment level, peak flow reductions reached 24.6% (2-year) and 26.4% (100-year). Flow routing at the catchment outlet revealed reductions in channel overflow volumes and maximum water heights by 75.5%, 54%, and 49% for 2-, 10-, and 50-year events, respectively.

This paper aims to evaluate the hydrologic impacts of urban expansion in a peri-urban catchment that drains into a reservoir of the drinking water supply system of Belo Horizonte Metropolitan Region in Brazil. Despite the metropolitan interest and efforts in protecting the catchment, a recent change in zoning ordinances allowed urban expansion in the area. To evaluate the potential hydrological impacts of this land use regulation change, scenarios of urban expansion were conceived and simulated in the model Dinamica EGO. The Storm Water Management Model (SWMM) was employed to assess potential hydrological impacts of land use change projections. Observed precipitation and water level data of the reservoir were used to calibrate and validate the hydrological model. Results confirm the impacts on several catchment hydrological processes following the progressive urban expansion in the area, particularly on volumes of infiltration, groundwater flow and runoff, increasing peak flows and flooding downstream the reservoir.

Green and blue infrastructure (GBI) is an urban planning approach that can reduce and mitigate the impacts of urbanization in the water cycle. This study evaluates the hydrologic impacts of a possible deployment of GBI in a peri-urban catchment under pressure from urban development. Considering cost-effectiveness, the best combinations of GBI techniques were simulated and compared with a scenario with urban expansion. A hydrological model in SWMM was applied to simulate impacts of GBI in runoff and a Hec-RAS model to assess the impact on flood. A combination of lot areas treated by rooftop disconnection and roads treated by vegetative swales achieved the lowest cost and one of the highest effectiveness in runoff reduction. Despite the growth of impervious area by almost 100% from urban expansion, the GBI scenario would bring the hydrological conditions and total flooded area downstream closer to the current scenario ones.

Understanding the major drivers of runoff water quality in urban areas is important for sustainable water management. In this study, runoff water quality in a catchment in Colombia and another in Brazil was monitored and related to rain, and meteorological variables through correlation and principal component analysis. High correlations were found between event mean concentration of total suspended solids (TSS) and total phosphorus (TP), as well as with total Kjeldahl nitrogen (TKN) and total organic carbon (TOC). The results indicated that TSS and TP were related to sediment transport in the catchment, while NTK and TOC were derived from point sources (improper wastewater disposal). Rain depth, maximum specific discharge, air temperature, and solar radiation were the main factors explaining variability of water quality. These results contribute to a better understanding of local processes driving runoff water quality, and bring valuable insights for modelling and management of stormwater in urban catchments.

To mitigate urbanization impacts on the hydrological cycle, Low Impact Development techniques, especially On-site Stormwater Detention - OSD, are applied worldwide. Besides their frequent use, the public knowledge about these techniques and stormwater management is insufficient, particularly in Latin America. Public comprehension about stormwater management and LID techniques lead to more acceptance and engagement. In this sense, the aim of this article is to present the results of interviews about local’s perception on stormwater management in Belo Horizonte/Brazil. The results indicate that males and respondents older than 40 years old have more knowledge about stormwater management, as well as higher socioeconomic interviewees. Although the use of OSD is positively perceived, a greater knowledge on urban stormwater does not lead to a greater willingness to co-participate in the stormwater management. Our results provide an overview of city inhabitants’ perception of municipal stormwater management and have great potential to help managers.