HydroPol2D -- Distributed Hydrodynamic and Water Quality Model: Challenges and Opportunities in Poorly-Gauged Catchments

Floods are one of the deadliest natural hazards and are fueled by excessive urbanization. Urban development decreases infiltration by reducing pervious areas and increases the accumulation of pollutants during dry weather. During wet weather events, there is an increase in the levels of pollution concentrations and stormwater runoff that eventually reach creeks and rivers. Polluted stormwater runoff may be sources of water supply. Modeling the quantity and quality dynamics of stormwater runoff requires a coupled hydrodynamic module capable of estimating the transport and fate of pollutants. In this paper, we evaluate the applicability of a distributed hydrodynamic model coupled with a water quality model (HydroPol2D). First, the model is compared to GSSHA and WCA2D in the V-Tilted catchment, and the limitation of the critical velocity of WCA2D is investigated. We also applied the model in a laboratory wooden board catchment, focusing on the validation of the numerical approach to simulate water quality dynamics. Then, we apply HydroPol2D in the Tijuco Preto catchment, in Sao Carlos - Brazil, and compare the modeling results with the full momentum solver of the Hydrologic Engineering Center - River System Analysis (HEC-RAS). The model implementation, the governing equations, and the estimation of input data are discussed, indicating the challenges and opportunities of the application of distributed models in poorly-gauged catchments. For a 1-yr return period of rainfall and antecedent dry days and assuming an uncertainty of $40\%$ in the water quality parameters, the results indicate that the maximum concentration of total suspended solids (TSS), the maximum load and the mass of the pollutant washed in $30\%$ of the volume are, $456~\pm~260~\mathrm{mg.L^{-1}.km^{-2}}$, $\mathrm{2.56 \pm 0.4~kg.s^{-1}.km^{-2}}$, and $\mathrm{89\%~\pm~10\%}$, respectively.Comment: Preprint submitted to Journal of Hydrolog

Low Impact Development practices in the context of United Nations Sustainable Development Goals: A new concept, lessons learned and challenges

The increase in urbanization and climate change brings new challenges to the cities’ sustainability and resilience, mainly related to flood and drought events. Among these challenges, it can be highlighted the physical and health damage to the population, interruption of water, energy and food supply services, damage to basic infrastructure, economic losses and contamination of urban rivers. To contribute to the increase of resilience in urban centers, LID practices have been used as a new approach of mitigation and adaptation within urban drainage systems, aiming at runoff retention, peak flow attenuation, pollutant removal and ecosystem services restoration (e.g., resources recycling, carbon sequestration, thermal comfort and landscape integration). These different mitigation purposes and complementary benefits provided by LID practices can be related to the different Sustainable Development Goals (SDG) presented by the United Nations (UN), to achieve countries’ systemic sustainability. The identification of local techniques that contribute to the different SDG helps to achieve their territorialization and application as public policy. Therefore, this paper presents a literature review, categorizing the studies into different generations based on their main application purpose and presents a linkage of the LID benefits to different SDG. Some challenges were identified requiring further investigation, such as the need to identify and quantify the energy demands for LID practices maintenance and their incorporation in the system final energy balance, identification of processes that contribute to carbon sequestration and emission, and risks of emerging pollutants for human health from water reuse and nutrient cycling for sustainable agriculture

Impactos das mudanças climáticas sobre a drenagem urbana subtropical com técnicas compensatórias

Low impact developments (LID) have been used to mitigate the effects of urbanization on the hydrological cycle. However, there is a lack of studies on LID performance in subtropical climates and under potential impacts of climate change scenarios. This dissertation evaluated the impacts of two climate change scenarios (RCP 4.5 and 8.5) on urban drainage with pollutants and their effect on LID practice efficiency located in a subtropical climate, with Cfa classification according to Köppen and Geiger. First, the inlet quantity and quality parameters were calibrated. The buildup/washoff model was evaluated, comparing load calibration and concentration of pollutants: chemical oxygen demand (COD), total organic carbon (TOC), phosphate (PO4) (NH3), iron (Fe), cadmium (Cd) and zinc (Zn). Pollutant washing was studied in the area of the bioretention catchment using historical rainfall data between 2013 and 2017, analyzing the influence of the buildup/washoff parameters of each pollutant in the input mass. Afterwards, Eta5x5km (INPE) climate change scenarios were disaggregated to 5-minute intervals by the modified Bartlett-Lewis method. The disaggregated series was used to estimate the impacts of climate change on urban drainage into the bioretention. Therefore, a simple model, developed specifically for the study bioretention cell, was used to estimate the qualitative-quantitative efficiencies of each period of the climate change scenarios. According to the data acquired from INPE, climate change will result in a fall in the volume of rainfall in São Carlos, resulting in lower volumes of surface runoff. The impacts on pollutant washing, however, vary according to the buildup/washoff parameters, explained by a sensitivity analysis. Climate change does not affect the bioretention quantitative efficiency very much: 81.7% from 1980 to 1999 to 81.4% and 81.3% from 2080 to 2099 for CPR scenarios 4.5 and 8.5. The pollutant removal efficiencies, as well as the washing, depend on buildup/washoff characteristics. One of the main consequences of climate change is a drop in the runoff quality. However, even with quantitative efficiency being maintained, bioretention is capable of mitigating this increase in the concentration of pollutants in urban drainage. Thus, the LID will help preserve the quality of downstream rivers, whose volumes will already have diminished by the decrease in rainfall volume.Técnicas compensatórias de drenagem (TC) vêm sido utilizadas para mitigar efeitos da urbanização no ciclo hidrológico. Entretanto faltam estudos sobre a performance destas TCs em clima subtropical e sob potenciais impactos de cenários de mudanças climáticas. Esta dissertação avaliou os impactos de dois cenários de mudanças climáticas (RCP 4.5 e 8.5) sobre o escoamento superficial urbano com poluentes e sua afetação na eficiência da TC localizada em clima subtropical, classificação Cfa segundo Köppen e Geiger. Primeiro se calibrou os parâmetros de quantidade e qualidade do escoamento superficial na entrada da biorretenção. O modelo buildup/washoff foi avaliado, comparando-se calibração da carga e concentração de poluentes: demanda química de oxigênio (DQO), carbono orgânico total (TOC), fosfato (PO4), nitrato (NO3), nitrito (NO2) amônia (NH3), ferro (Fe), cadmio (Cd) e zinco (Zn). Então se estudou a lavagem de poluentes na área de contribuição da biorretenção com histórico de precipitação entre 2013 e 2017 e analisando a influência dos parâmetros buildup/washoff de cada poluente na entrada de massa. Em seguida, cenários de mudanças climáticas Eta-5x5km (INPE) foram desagregados em intervalos de 5 minutos, pelo método de Bartlett-Lewis modificado. A série desagregada foi utilizada para se estimar os impactos das mudanças climáticas na drenagem urbana, a incidir na biorretenção. Então um modelo simples desenvolvido especificamente para a biorretenção em estudo foi usado para se estimar as eficiências quali-quantitativas de cada período dos cenários de mudanças climáticas. Os dados adquiridos do Inpe mostram que as mudanças climáticas resultarão em uma queda no volume de chuvas em São Carlos, resultando em menores volumes de escoamento superficial. Os impactos na lavagem de poluentes, entretanto, variam de acordo com os parâmetros buildup/washoff, explicados por uma análise de sensibilidade. As mudanças climáticas pouco afetam a eficiência quantitativa da biorretenção, 81.7% no período 1980-1999 para 81.4% e 81.3% no período 2080-2099 para cenários RCP 4.5 e 8.5. Já as eficiências de remoção de poluentes, assim como a lavagem destes, dependem das características buildup/washoff de lavagem. Uma das principais consequências observadas das mudanças climáticas é uma queda na qualidade do escoamento. Porém, mesmo com eficiência quantitativa sendo mantida, a biorretenção é capaz de amenizar essa o aumento na concentração de poluentes na drenagem urbana. Assim, a técnica ajudará a preservar a qualidade dos rios à jusante, que já terão seus volumes diminuídos pela queda no volume de chuva

Simulation and optimization framework for evaluating the robustness of low-impact development placement solutions under climate change in a small urban catchment

The lack of acceptable temporal resolution of climate projections hinders proper assessment of the future performance of low-impact development (LID) systems in small catchments when continuous simulations are required (e.g. to evaluate infiltration). This study applied a simulation optimization approach to maximize infiltration with LIDs at minimum costs in a small urban catchment (0.67 km2). We coupled the Storm Water Management Model (SWMM) with the Nondominated Sorting Genetic Algorithm II (NSGA-II) to determine near-optimal locations of bioretentions, green roofs, and permeable pavements. The temporal resolution of rainfall projections was disaggregated from 24 hours to 15 minutes using the Bartlett-Lewis rectangular method to evaluate the performance and robustness of the optimized solutions under different budgets and climate scenarios. Results suggest that LIDs can mitigate climate change impacts with relatively inexpensive solutions. However, the robustness analysis showed that climate change could compromise the expected performance of LIDs sized with historical rainfall.</p

Performance of bioretention experimental devices: contrasting laboratory and field scales through controlled experiments

<div><p>ABSTRACT Studying the performance of LID devices on a laboratory scale has the advantage of flexible layouts, so that more factors can be tested. However, they do not always correspond to what happens on a real scale of application. This paper focuses on a comparative analysis between two bioretention experimental devices considering field and laboratory scales. Based on this comparison, our understanding can be enhanced to extrapolate the results. Flow rate and duration were used as the main equivalence parameters. However, these parameters were insufficient to ensure similarity in the results. We proposed to include control volume, an application rate and an equivalent net depth as new parameters. Further research should test the variation of these parameters.</p></div

Performance of bioretention experimental devices: contrasting laboratory and field scales through controlled experiments

<div><p>ABSTRACT Studying the performance of LID devices on a laboratory scale has the advantage of flexible layouts, so that more factors can be tested. However, they do not always correspond to what happens on a real scale of application. This paper focuses on a comparative analysis between two bioretention experimental devices considering field and laboratory scales. Based on this comparison, our understanding can be enhanced to extrapolate the results. Flow rate and duration were used as the main equivalence parameters. However, these parameters were insufficient to ensure similarity in the results. We proposed to include control volume, an application rate and an equivalent net depth as new parameters. Further research should test the variation of these parameters.</p></div