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

Técnicas descentralizadas para reciclagem de águas de drenagem urbana visando a segurança hídrica-energética-alimentar

Low Impact Development (LID) practices are low-cost adaptation alternatives to assist traditional drainage systems, aiming at mitigating the risks of hydrological extremes. In this project, a new nomenclature is used for LID, facing the extremes due to change in future scenarios and their adaptations. For example, when they are adapted for changes in land use and occupation, e.g. urbanization, they are called 1st generation LID (LID-1G). When incorporating adaptations of land use and climate change, they are called 2nd generation (LID-2G). Also, when the adaptation incorporates the recycling of resources for water-energy-food security, they are called 3rd generation (LID-3G). However, scientific gaps still remain because: few studies evaluate the combined qualitative and quantitative efficiency of LID-1G and LID-2G; for LID-3G, there is limited knowledge about incorporating climate change scenarios and resource recycling to reduce water-energy-food security risks; these gaps are still larger in areas of subtropical climate and when applied in a decentralized way. Therefore, this doctoral research enhances a new theoretical-experimental framework on a new LID-3G of bioretention, for decentralized use. The methodology addresses three stages: (1) analysis of design incorporating future scenarios with drivers of change of urbanization and climate; (2) new criteria for operation, maintenance and runoff volume and water quality monitoring for 3rd generation, in field scale and laboratory scale, (3) proposition and study of new evaluation coefficients aiming at resources recycling, contribution to water-energy-food security and local sustainability. The results were discussed under conditions of: (a) subtropical climate, (b) Brazilian urbanization standards, and (c) social demands for water-energy-food security.Técnicas compensatórias de drenagem urbana sustentável (TCs) são alternativas de adaptação de baixo custo que auxiliam os sistemas clássicos de drenagem, visando a mitigação dos riscos de extremos hidrológicos. Neste projeto, uma nova nomenclatura é utilizada para TCs frente a estes extremos de cenários futuros de mudanças e suas adaptações. Por exemplo, quando são adaptadas para mudanças de uso e ocupação do solo, p. ex. da urbanização, são denominadas Técnicas Compensatórias de 1ª geração (TCs-1G). Quando incorporam adaptações de uso do solo e mudanças climáticas, são denominadas de 2ª geração (TCs-2G). Ainda, quando a adaptação incorpora a reciclagem de recursos para segurança hídrica-energética-alimentar, são denominadas de 3ª geração (TCs-3G). Contudo, vazios científicos ainda permanecem, porque: poucas pesquisas avaliam a eficiência quali-quantitativa, de forma combinada, das TCs-1G e TCs-2G. Também, para as TCs-3G, existe um conhecimento limitado quanto ao emprego de cenários de mudanças climáticas e reciclagem de recursos para redução de riscos de segurança hídrica-energética-alimentar. Ainda, estes vazios ainda são maiores em áreas de clima subtropical e quando aplicadas de forma descentralizada, espacialmente dentro da bacia hidrográfica. Assim, esta pesquisa de doutorado aprimora um marco teórico-experimental, a partir do desenvolvimento conceitual e experimental sobre novas TCs-3G para uso descentralizado e para segurança do nexo água-energia-alimentos. A metodologia aborda três etapas: (1) análise de dimensionamento incorporando cenários futuros sob mudanças de urbanização e clima, (2) novos critérios de operação, manutenção e monitoramento quali-quantitativo de TCs visando terceira geração, em escala de campo e em escala de laboratório, (3) proposição e estudo de novos coeficientes de avaliação visando reciclagem de recursos, contribuição para segurança hídrica-energética-alimentar e sustentabilidade do local. Os resultados foram discutidos sob condições de: (a) clima subtropical, (b) padrões brasileiros de urbanização e (c) locais com demandas sociais por segurança hídrica-energética-alimentar

Otimização de técnicas compensatórias de drenagem urbana em clima subtropical

The urban drainage in Brazil has been focused historically in the hydraulic conduction of the runoff. From the 1990\'s a paradigm shift was initiated with the study of LID practices, aiming at adapting the local scenario to compensate the urbanization effects on runoff and reestablish the water cycle as close as possible to the natural. However, there is still a gap regarding the integration of qualitative-quantitative variables and their comprehension. In addition, the temperate climate regions have been in the center of the studies, with still few knowledge about other climates influence in its efficiency. Therefore, this research aimed to evaluate the operation of a bioretention structure in a subtropical climate region, regarding mainly its pollutant treatment capacity and water retention, in an integrated way. The results indicate a positive use of the bioretention in reducing the exceedance risks, by reducing the peak flow, the total volume and the pollutant load transferred downstream. However, adaptations the implementation and operation stages are necessary for subtropical climates. The local specific characteristics, such as soil highly weathered and rainfall with high intensities in short intervals of time, affect the water and pollutant retention efficiency. Further studies evaluating different applications locals and scales, and treatment key factors must be performed.A drenagem urbana no Brasil esteve focada historicamente no tratamento hidráulico para a condução do escoamento superficial. A partir da década de 90 se inicia uma mudança de paradigma com o estudo de técnicas compensatórias (TCs), visando adaptar o cenário local para compensar os efeitos da urbanização sobre o escoamento superficial, de forma a manter o ciclo hidrológico o mais próximo possível do natural. No entanto, existe ainda uma lacuna quanto a integração das variáveis quali-quantitativas e sua compreensão. No mais, as regiões de clima temperado estiveram no centro dos estudos, havendo pouco conhecimento sobre a influência de outros climas em sua eficiência. Assim, a presente pesquisa teve como objetivo avaliar a operação de uma estrutura de bioretenção em uma região de clima subtropical, quanto a sua capacidade de tratamento da poluição difusa e retenção hídrica de forma integrada. Para tal, foram monitorados dois dispositivos em escalas distintas, sendo essas laboratório e campo. Os resultados obtidos indicaram um uso promissor da bioretenção em reduzir os riscos de enchente, reduzindo a vazão de pico e o volume total transferido à jusante, assim como a carga total de poluentes. No entanto, adaptações nas etapas de implantação e operação são necessárias para clima subtropical. As características específicas desses locais, como solos altamente intemperizados e regimes de chuva de alta intensidade em pequeno intervalo de tempo, afetam a eficiência de retenção hídrica e retenção de poluente. Novos estudos avaliando diversos locais, escalas de aplicação, e fatores-chave para o tratamento devem ser realizados

Modular Design of Bioretention Systems for Sustainable Stormwater Management under Drivers of Urbanization and Climate Change

The increase in urbanization and climate change projections point to a worsening of floods and urban river contamination. Cities need to adopt adaptive urban drainage measures capable of mitigating these drivers of change. This study presents a practical methodology for a modular design of bioretention systems incorporating land use and climate change into existing sizing methods. Additionally, a sensitivity analysis for these methods was performed. The methodology was applied to a case study in the city of Sao Carlos, SP, Brazil. Three application scales were evaluated: property scale (PS), street scale (SS) and neighborhood scale (NS) for three temporal scenarios: current, 2015–2050 and 2050–2100. The choice of the sizing method was the factor with greatest influence on the final bioretention performance, as it considerably affected the surface areas designed, followed by the hydraulic conductivity of the filtering media. When analyzing the sensitivity of the parameters for each method, the runoff coefficient and the daily precipitation with 90% probability were identified as the most sensitive parameters. For the period 2050–2100, there was an increase of up to 2×, 2.5× and 4× in inflow for PS, SS and NS, respectively. However and despite the great uncertainty of future drivers, bioretention performance would remain almost constant in future periods due to modular design

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

Linking Urban Floods to Citizen Science and Low Impact Development in Poorly Gauged Basins under Climate Changes for Dynamic Resilience Evaluation

Cities must develop actions that reduce flood risk in the face of extreme rainfall events. In this study, the dynamic resilience of the Gregorio catchment (São Carlos, Brazil) was assessed. The catchment lacks environmental monitoring and suffers from recurrent floods. The resilience curves were made considering the water depth in the drainage system as the performance index, obtained by simulations with SWMM and HEC-RAS. The calibration of the flood extension was performed using citizen science data. The contribution to increasing the dynamic resilience by implementing decentralized low impact development (LID) practices was also evaluated. For this purpose, bioretention cells were added to the SWMM simulations. The resilience curves were then calculated for the current and future climate scenario, with and without LID, for return periods of 5, 10, 50, and 100 years and duration of 30, 60, and 120 min. Intensity–duration–frequency curves (IDFs) updated by the regional climate model MIROC5 for 2050 and 2100 were used. The results showed a significant improvement in the system’s resilience for light storms and the current period due to LID practice interventions. Efficiencies were reduced for moderate and heavy storms with no significant drops in floodwater depth and resilience regardless of the scenario

Enhancing drought resilience and vulnerability assessment in small farms: A global expert survey on multidimensional indicators

The purpose of the paper is to evaluate drought vulnerability and resilience within the context of small-scale farms. Small-scale farms are distinguished by their family-oriented motives, which prioritize maintaining the stability of the household farm system. This type of farming is responsible for a significant part of the world's food production, thus identifying their vulnerability and resilience to drought is essential to avoid adverse socioeconomic impacts. The paper contributes to this issue by presenting the findings of a comprehensive global survey conducted among experts on drought risk analysis, focusing on indicators related to drought resilience and vulnerability in small-scale farming. An online questionnaire was sent to experts asking them to rate a list of 36 indicators in terms of five metrics: relevancy, accessibility, objectivity, understanding, and temporal consistency. Each indicator was rated on a three-point scale (low, medium, and high). The survey was entirely completed by 120 experts from 42 countries and different areas of expertise. The survey results offer a comprehensive evaluation of multiple indicators, contributing to future research by guiding the selection of indicators for composite drought resilience indexes and enhancing the understanding of farmers' and food systems' climate resilience. The survey results indicate that: i) government and institutional indicators are very relevant for drought resilience assessment; ii) there is an undefined role for social indicators in drought vulnerability assessment; iii) experts still do not perceive the importance of local engagement in drought risk management; iv) the use of relevant indicators in drought risk assessment can be limited because of a lack of accessibility and temporal consistency.Engineering and Physical Sciences Research Council (EPSRC

Towards urban resilience through Sustainable Drainage Systems: A multi-objective optimisation problem

The necessity of incorporating a resilience-informed approach into urban planning and its decision-making is felt now more than any time previously, particularly in low and middle income countries. In order to achieve a successful transition to sustainable, resilient and cost-effective cities, there is a growing attention given to more effective integration of nature-based solutions, such as Sustainable Drainage Systems (SuDS), with other urban components. The experience of SuDS integration with urban planning, in developed cities, has proven to be an effective strategy with a wide range of advantages and lower costs. The effective design and implementation of SuDS requires a multi-objective approach by which all four pillars of SuDS design (i.e., water quality, water quantity, amenity and biodiversity) are considered in connection to other urban, social, and economic aspects and constraints. This study develops a resilience-driven multi-objective optimisation model aiming to provide a Pareto-front of optimised solutions for effective incorporation of SuDS into (peri)urban planning, applied to a case study in Brazil. This model adopts the SuDS's two pillars of water quality and water quantity as the optimisation objectives with its level of spatial distribution as decision variables. Also, an improved quality of life index (iQoL) is developed to re-evaluate the optimal engineering solutions to encompass the amenity and biodiversity pillars of SuDS. Rain barrels, green roofs, bio-retention tanks, vegetation grass swales and permeable pavements are the suitable SuDS options identified in this study. The findings show that the most resilient solutions are costly but this does not guarantee higher iQoL values. Bio-retention tanks and grass swales play effective roles in promotion of water quality resilience but this comes with considerable increase in costs. Permeable pavements and green roofs are effective strategies when flood resilience is a priority. Rain barrel is a preferred solution due to the dominance of residential areas in the study area and the lower cost of this option