Modelling-based methodological approach to assess the effect of urbanization on hydrology and runoff water quality: a case of study for tropical and dry regions

ABSTRACT: It is necessary to have unified tools and methodologies for the correct understanding and quantification of urbanization effects on watershed hydrology. This study presents a modelling-based methodology developed on EPA SWMM to evaluate the effect of urbanization in conceptual watersheds using meteorological data from cities in Spain and Colombia. Results show that the effect of urbanization is significant in variables such as runoff volume, peak flow and pollutant loads, increasing these indicators in all cases. Furthermore, this effect has different dynamics for the regions evaluated. Overall, Colombian cities presented higher runoff volumes, peak flows and pollutant loads, while Spanish cities presented higher variability in these variables due to urbanization. The analysis allowed to cluster the cities within each country, using as criteria the modelled hydrological behaviour. A curve fitting procedure presented high performance rates for all the variables studied.This work was supported by the ‘Instituto Colombiano de Crédito Educativo y Estudios Técnicos en el Exterior’ (ICETEX) under the program ‘Pasaporte a la Ciencia’ granted to the first author under grant number 5334506

Flood Management with SUDS: A Simulation-Optimization Framework

ABSTRACT: Urbanization and climate change are the main driving force in the development of sustainable strategies for managing water in cities, such as sustainable urban drainage systems (SUDS). Previous studies have identified the necessity to develop decision-making tools for SUDS in order to adequately implement these structures. This study proposes a simulation?optimization methodology that aims to ease the decision-making process when selecting and placing SUDS, with the specific goal of managing urban flooding. The methodology was applied to a real case study in Dresden, Germany. The most relevant variables when selecting SUDS were the spatial distribution of floods and the land uses in the catchment. Furthermore, the rainfall characteristics played an important role when selecting the different SUDS configurations. After the optimal SUDS configurations were determined, flood maps were developed, identifying the high potential that SUDS have for reducing flood volumes and depth, but showing them to be quite limited in reducing the flooded areas. The final section of the study proposes a combined frequency map of SUDS implementation, which is suggested for use as a final guide for the present study. The study successfully implemented a novel methodology that included land-use patterns and flood indicators to select SUDS in a real case study.This research was funded by ICETEX, grant number 5334506, granted to the first author. This research was funded by the German Federal Ministry of Education and Research, grant number 01LR2005A

Flood Management with SUDS: A Simulation–Optimization Framework

Urbanization and climate change are the main driving force in the development of sustainable strategies for managing water in cities, such as sustainable urban drainage systems (SUDS). Previous studies have identified the necessity to develop decision-making tools for SUDS in order to adequately implement these structures. This study proposes a simulation–optimization methodology that aims to ease the decision-making process when selecting and placing SUDS, with the specific goal of managing urban flooding. The methodology was applied to a real case study in Dresden, Germany. The most relevant variables when selecting SUDS were the spatial distribution of floods and the land uses in the catchment. Furthermore, the rainfall characteristics played an important role when selecting the different SUDS configurations. After the optimal SUDS configurations were determined, flood maps were developed, identifying the high potential that SUDS have for reducing flood volumes and depth, but showing them to be quite limited in reducing the flooded areas. The final section of the study proposes a combined frequency map of SUDS implementation, which is suggested for use as a final guide for the present study. The study successfully implemented a novel methodology that included land-use patterns and flood indicators to select SUDS in a real case study

Evaluación Experimental de la Capacidad de Retención y Efectos en la Calidad del Agua de Escorrentía Pluvial de Techos Verdes Modulares

Este estudio evaluó la retención y la calidad de agua de la escorrentía de 15 diferentes configuraciones modulares de techos verdes (TV) localizados en el campus principal de la Universidad de los Andes (Bogotá, Colombia). Con base en 69 eventos de lluvia analizados durante un periodo de 2 años, el porcentaje de retención medio para los sistemas evaluados fue de 73%. Se realizaron análisis estadísticos (ANOVA y regresiones lineales múltiples) con el fin de identificar aquellas variables que inciden en los porcentajes de retención (p.e. temperatura ambiente, humedad relativa, tipo de sustrato y vegetación, tiempo antecedente seco [TAS], duración e intensidad de lluvia). Las variables de diseño de los techos verdes mostraron ser relevantes para los porcentajes de retención y dependiendo del montaje experimental, las variables climatológicas también mostraron estar correlacionadas con el porcentaje de retención. Adicionalmente, el agua lluvia y la escorrentía de los techos verdes y de una teja de referencia (plástico) fueron monitoreadas para Nitrógeno Total Kjeldahl (NTK), Nitratos, Nitritos, Amonio, Fósforo Total (FT), Fosfatos, pH, Sólidos Disueltos Totales (SDT), Sólidos Suspendidos Total (SST), Color, Turbiedad, Demanda Biológica de Oxígeno (DBO), Demanda Bioquímica de Oxígeno (DQO), Coliformes Totales, Metales e Hidrocarburos Aromáticos Policíclicos (HAP). Los resultados obtenidos confirmaron la habilidad de los techos verdes para neutralizar el pH así como aporte de cargas contaminantes del resto de parámetros mencionados previamente, a excepción de los HAP, con concentraciones por debajo del límite de detección para todos los puntos muestreados. Los resultados evidenciaron cargas contaminantes variables dependiendo del tipo de sustrato y vegetación de los techos verdes.This study assessed the hydrological performance and runoff water quality of 15 different green roof (GR) modular systems located at the Universidad de Los Andes campus (Bogotá, Colombia). Based on 69 rainfall events spanning a 2-year period, average rainfall retention for the different evaluated systems was 73%. Some statistical analysis (ANOVA and Multiple Linear Regressions) were carried out, in order to statistically assess those variables that could potentially control retention values (i.e. air temperature, growing media, type of plant species, humidity, antecedent dry weather period [ADWP], rainfall duration and rainfall maximum intensity). Design variables were found to be relevant for the retention efficiency and depending on the set-up, climatological variables were also correlated with the retention. Rainfall and GR runoff were monitored for Total Nitrogen Kjeldahl (TNK), Nitrates, Nitrites, Ammonia, Total Phosphorus (TP), Phosphates, pH, Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Color, Turbidity, BOD, COD, Total Coliform, metals and Poliaromatic Hydrocarbons (PAHs). Obtained results confirmed that GR systems have the ability to neutralize pH but are source of the rest of the aforementioned parameters, excluding PAHs, with concentrations below detection limits for all measurement points

Modelización y Optimización de SUDS Como Apoyo a la Toma de Decisiones/SUDS Modeling and Optimization to Support Decision-Making

359 p.La presente tesis tuvo el objetivo principal de plantear un esquema metodológico de modelización de los SUDS, a partir del cual se pudiera aportar de manera sistemática a la toma de decisiones en proyectos de drenaje urbano. Para lo anterior, propuso algoritmos y estrategias innovadoras de acople entre modelos hidráulicos y algoritmos de optimización. Los resultados de la primera fase de la tesis pusieron a prueba la metodología de automatización de modelos, y permitieron construir unas bases sólidas en lo que respecta al efecto y la cuantificación de la urbanización en la hidráulica e hidrología del agua urbana. Usando la misma metodología de automatización y el escenario base ya planteado, el siguiente capítulo de la tesis permitieron hacer un balance respecto al efecto y sensibilidad de los parámetros de diseño de los SUDS, llegando a una propuesta de diseño para cada estructura. . Posteriormente, se planteó el esquema de acople de los modelos a algoritmos de optimización, lo cual permitió llegar a configuraciones costo-eficientes de los SUDS, así como evidenciar el marcado efecto de la combinación de tipologías, los trenes de SUDS, así como del tipo de modelación temporal en el desempeño de SUDS. Una vez planteado el esquema de simulación-optimización de SUDS, fue puesto a prueba en un caso de estudio

Continuous quantity and quality modeling for assessing the effect of SUDS: application on a conceptual urban drainage basin

The development of computational tools based on urban drainage models is fundamental for the correct selection of SUDS. The present study proposes a systematic approach based on continuous modeling on USEPA SWMM. The objective was to select the most suitable Sustainable Urban Drainage Systems (SUDS) by evaluating several aspects related to their design and configuration. The proposed methodology was applied to a conceptual watershed with meteorological information from Santander, Spain. The analysis of SUDS design parameters showed that only the surface variables showed a sensitivity of ≈20% for berm height and vegetation volume. The optimal configuration for the case study was a SUDS train consisting of green roofs, permeable pavements, vegetated swales and rain gardens, with 1% of the total subcatchment area cover, one structure, and a semi-aggregated spatial distribution. The methodology proved efficient but also highly dependent on the case study parameters and the meteorological conditions. The SUDS proved to have different efficiencies (30%-90%) in reducing the total runoff volume, the peak flow, and the pollutant loads depending on the region where the conceptual watershed was modeled. The methodology proved to be efficient for studying the combinations and interconnection of seven different typologies, as well as the effect of SUDS configuration, design and distribution on their performance.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by the “Instituto Colombiano de Crédito Educativo y Estudios Técnicos en el Exterior” (ICETEX) under “Pasaporte a la Ciencia” program, granted to the first author under the grant number 5334506

Sustainable Urban Drainage System (SUDS) modeling supporting decision-making: A systematic quantitative review

ABSTRACT: Decision Support Systems (DSS) for Sustainable Urban Drainage Systems (SUDS) are a valuable aid for SUDS widespread adoption. These tools systematize the decision-making criteria and eliminate the bias inherent to expert judgment, abridging the technical aspect of SUDS for non-technical users and decision-makers. Through the collection and careful assessment of 120 papers on SUDS models and SUDS-DSS, this review shows how these tools are built, selected, and used to assist decision-makers questions. The manuscript classifies the DSS based on the question they assist in answering, the spatial scale used, the software selected, among other aspects. SUDS-DSS aspects that require more attention are identified, including environmental and social considerations, SUDS trains performance and criteria for selection, stochasticity of rainfall, and future scenarios impact. Suggestions for SUDS-DSS are finally offered to better equip decision-makers in facing emerging stormwater challenges in urban centers

Effect of green roof configuration and hydrological variables on runoff water quantity and quality

Green roofs (GRs) are a feasible solution for mitigating increased runoffvolumes in urban areas. Though many studies have focused their analysis on the quantity and quality of GR runoff, with respect to the relevance of specific site conditions in GR performance, the information gathered for the tropical Andes is not sufficient. This study assessed the hydrological performance and runoffwater quality of 12 green roof modular systems located at the Universidad de los Andes campus (Bogotá, Colombia). Based on 223 rainfall events spanning a 3-year period, average rainfall retention was 85% (coefficient of variation = 29%). t-tests, the Welch Test, multiple linear regressions, and correlation analysis were performed in order to assess the potential effect of air temperature, substrate type, vegetation cover, relative humidity, antecedent dry weather period (ADWP), rainfall duration, and rainfall maximum intensity. In some cases, GR design variables (i.e., substrate type and vegetation cover) were found to be significant for describing rainfall retention efficiencies and, depending on the GR type, some hydrological variables were also correlated with rainfall retention. Rainfall and GR runofffrom 12 rainfall events were also monitored for total Kjeldahl nitrogen (TKN), nitrates, nitrites, ammonia, total phosphorus (TP), phosphates, pH, total dissolved solids (TDS), total suspended solids (TSS), color, turbidity, biological oxygen demand (BOD), chemical oxygen demand (COD), total coliforms, metals (i.e., zinc, copper, nickel, lead, selenium, aluminum, barium, boron, calcium, strontium, iron, lithium, magnesium, manganese, potassium, sodium), and polyaromatic hydrocarbons (PAHs). The results obtained confirmed that GR systems have the ability to neutralize pH, but are a source of the rest of the aforementioned parameters, excluding PAHs (with concentrations below detection limits), ammonia, TSS, selenium and lithium, where differences with control cases (rainfall and plastic panel runoff) were not statistically significant. Substrate type, event size, and rainfall regime are relevant variables for explaining runoffwater quality