Paranoá Lake is an urban lake and it is being used as a source for urban water supply since last year. Until 1990, algal blooms occurred and improvements on wastewater treatment plants carried out improved the water quality very rapidly due to phosphorus load reduction. Recently, water quality is deteriorating, which is probably due to diffuse pollution. In Brazil, we adopt separated pipe networks for sewage and stormwaters, although cross flows occur. The evaluation of urban drainage stormwaters entering the lake and proposition of technical alternatives is crucial in minimizing the impacts on lake water quality. Quantitative and qualitative behavior of urban stormwaters were analyzed by means of monitoring the runoff flows and pollutant concentrations. Mathematical modelling while using the Storm Water Management Model—SWMM was carried out, and good correlations were found for flow modelling. However, poor response was achieved for water quality simulations, affecting the simulated pollutant loads entering the lake. The simulation of 13 alternatives for detention ponds location was also evaluated, as well as their influences on flow damping capability. The detention ponds that were tested were placed in line in the drainage mains to study the effects of their location on the removal of pollutants. As expected, the results showed that ponds located near the outfall are more efficient in reducing flow peaks. However, this layout requires construction woks in areas that are more sensitive to environmental and urbanistic problems and with higher land commercial values. Alternatives with smaller volumes in public areas near the center of the catchment area can lead to the peak flow damping required by the existing drainage network to avoid overflows. In conclusion, detention ponds can be a good alternative for improving the stormwater quantity and quality, but also alternatives that promote increased infiltration, should also be considered for compensating the infiltration lost due to urbanization.

Urban stormwater runoff is an important source of pollution in receiving water bodies, mainly in cities in development. However, strategies to deal with the impacts caused by the runoff discharges, such as implementing a sustainable urban drainage system (SUDS) with optimized management, need information usually obtained through monitoring studies. Brasília is a city that has one of the highest urban growth rates in Brazil, with significant impacts on urban water resources, including diffuse pollution, generated by new unregulated urban developments that initially start being built with precarious sanitation infrastructure. The Vicente Pires (VP) watershed is highly urbanized and comprises two areas that have been intensively occupied more recently, at a fast pace, and do not have yet basic sanitation systems fully implemented. Stormwater quality at the outlet of the VP watershed was analyzed by monitoring the rainfall, runoff flows, and pollutant concentration. Event Mean Concentration (EMC) and first-flush (FF) phenomenon were calculated, and hydrologic characteristics were compared for different events through correlation analysis. During dry periods the flow varied between 0.5 and 1.29 m³/s, while in flood periods the maximum value was 72.17 m³/s, forming floods with great volume. Nitrate during dry periods stands out with its high concentration; the maximum was 1.49 mg/L, while the maximum concentration during the flood events was 0.43 mg/L, probably due to dilution. Ammonia results showed very low values, probably because nitrification is occurring up to the collection point. The EMC values of solids in flood events were higher and can be attributed to river bed scour along the VP watershed. The EMC SS values for the VP watershed are also similar to areas in the initial stages of building development. The EMC values in the dry season indicate strong correlations between some water quality parameters such as NH⁺³-N and SS, TS and NO₋₃-N; NO₋₃-N, and COD. These correlations indicate that these pollutants are probably being generated by the same source, probably sewage discharges. During flood events, the correlation between pollutant loads and peak flow can be associated with the scouring during surface washing off, because greater concentrations of solids and organic matter occur in events with greater flow rates. For the first 30% of the initial runoff volume, about 29% of SS, 38% of NH⁺³-N, and 35% of reactive P were carried during flood events. It was verified that large values of maximum or mean rainfall intensity are related to the occurrence of First Flush (FF) for most pollutants. Antecedent dry days (ADD) did not influence build-up processes in this watershed; however, they are related to FF occurrence. Data indicate that the sewage and stormwater collection networks were being installed caused a high impact on observed water quality, with high concentrations of solids during flood events. On the other hand, the wastewater collection after the sewer network installation led to a decrease in COD concentrations over time. For sustainable management of diffuse pollution, the adoption of distributed SUDS to enhance runoff volume reduction is a recommended solution for the case.

Diffuse pollution loads are crucial information for water resource management, and yet field data are often scarce, implying questionable accuracy in load estimates made from low-frequency water quality monitoring. This paper aimed to characterize diffuse pollution in a stream of a mixed-land-cover watershed with a significant portion of urbanized areas through intensive monitoring and to perform a comparative analysis between the loads estimated by pollutant rating curves obtained by regression and the estimates using monthly water quality data, which is the method currently used. Continuous rainfall and flow monitoring was conducted between 2019 and 2021, and samples were collected during flood events and the dry period for water quality analysis. Flood events were found to induce an increase in suspended solids (TSS) and COD concentrations, while inorganic nitrogen (Inorg-N) concentrations were higher in the dry season. Flood characteristics showed a positive correlation with solids and COD event mean concentrations (EMCs) and negative with Inorg-N EMCs, while rainfall characteristics, such as antecedent dry days and intensity, correlate positively with all these pollutants. The rating curves performed well for total load estimation in low discharge events (R² and NSE > 0.8), except for total phosphorus (TP) loads. Estimated annual unit loads found for the watershed were 2 ton TSS/ha.year, 300 kg COD/ha.year, 5 kg Inorg-N/ha.year, and 0.5 kg TP/ha.year, showing high pollution generated in the watershed. Finally, a comparison with estimates based on monthly monitoring data indicated that this method is sufficient for accurate nutrient loads, but not for TSS and COD loads, which require continuous monitoring to improve the accuracy of estimation.

Falta de interação das áreas de urbanismo e infraestrutura urbana de drenagem resultam em alagamentos e/ou deslizamentos sejam decorrentes de ausência de infraestutura ou as vezes da adoção de técnicas tradicionais que levam ao desequilíbrio do ciclo da água nas cidades. O presente artigo visa simular a contribuição efetiva da infraesturutra verde, que se utiliza da lógica do metabolismo circular urbano, para minimização dos impactos de alagamentos urbanos. Foi estudada uma bacia de drenagem em Brasília, com considerável percentual de áreas verdes que, possui sistema convencional de drenagem e que conta com alagamentos recorrentes. A pergunta a ser respondida é como se apropriar das áreas verdes para explorar seu potencial de infiltração reduzindo os alagamentos? Como método se utilizou mapas de uso e ocupação do solo e programa CAD na seleção de áreas públicas da bacia com predominância de vegetação para inserção de trincheiras e jardins de chuva com posteriormente simulação dos processos hidráulicos e hidrológicos no modelo SWMM. Como resultado se obteve dados quantitativos para propor medidas de infraestrutura verde que significam a maximização da infiltração e um percentual menor de escoamento para ser resolvido por técnicas tradicionais significando maior equilibrio ecossitêmico e redução de impactos ambientais

The increase in runoff volume due to urban sprawl has imposed a challenge to current urban drainage systems and future projects in order to add sustainable strategies for effective flood control especially in consolidated urban areas that would require retrofitting of urban areas with additional social and economic costs. This study is aimed at evaluating alternatives of drainage solutions in a consolidated urban area in the Federal District of Brazil, located in Savanna region, based on the reduction of peak flow and flooded volume in the areas exposed to flood hazard. Different solutions based on the concepts of Low Impact Development (LID) were simulated, showing that the current traditional drainage system is not in compliance with local regulations in the Federal District. In addition, the use of permeable pavements and stormwater ponds could reduce at least 46% of the flooded volume. When placed along with the drainage network, not only at the outlet, stormwater ponds were able to reduce the flooded volume and its hazard and damages. However, LIDs solutions were not able to completely eliminate floods in the region. Structural changes, as resizing the conduits into the drainage systems in the area, could improve the drainage system effectiveness avoiding floods and respective hazards and damages.