Nature Based Solutions for Sustainable Urban Storm Water Management in Global South: A Short Review

Rapid urbanization in the Global South exacerbates urban water management challenges such as urban flooding and water pollution, rendering many areas water-insecure. Our reliance on grey infrastructures to combat these water management challenges is not sustainable in the long run, due to which a better alternative must be sought. Nature-based Solution (NBS) promote ecosystem services and enhance climate resiliency along with flood control and improvement of water quality by utilizing natural elements including green spaces and water bodies within the urban environment. In the past few decades, NBS have been adapted for urban drainage in Global North and evolved by means of various terms based on geographic location, practices and applications. Some of these well-known terms include Low Impact Development (LIDs), Sustainable Urban Drainage Systems (SUDS), Water Sensitive Urban Design (WSUD) and Best Management Practices (BMPs). The transition towards a resilient and sustainable environment has been made possible through the application of NBS. Recently, countries in the Global South such as Singapore, Malaysia, Vietnam, and Thailand are trying to alter urban storm water management strategies through conversion of grey infrastructure to green infrastructure by employing various NBS techniques. The findings of this study show how NBS has influenced the Global South’s urban water management.

Probabilistic Modelling of Sustainable Urban Drainage Systems

Sustainable Urban Drainage Systems (SuDS) gatherer effective strategies and control systems for stormwater management especially in highly urbanized areas characterized by large impervious surfaces that increase runoff peak flow and volume. The main goal is to restore the natural water balance by increasing infiltration, evapotranspiration and promoting rainwater reuse. This paper proposes an analytical probabilistic approach for the modelling SuDS applicable to different structures and goals. Developed equations allow to estimate the probability of overflow and the probability of pre-filling at the end of dry periods, to evaluate the efficiency of the storage in rainwater management and its ability to empty between consecutive events. A great advantage of the proposed method is that it allows to consider a chain of rainfall events; this aspect is particularly important for control systems SuDS characterized by low outflow rates which storage capacity is often not completely available at the end of a dry period because pre-filled by previous events. Suggested formulas were tested to two cases studies in Milan and Genoa, Italy.

Application of GIS on building the spatial database for supporting drainage management in Ninh Kieu District

Ninh Kieu District is located in the center of Can Tho City, established under the Government’s Decree No. 05/2004/ND-CP. This is a modern and rich district, with a history of formation and development associated with the Mekong Delta. According to statistics in 2019, Ninh Kieu District has an average population of 280,792 people, with a population density of 9,605 people/km2 and an area of 29.23 km2. In the current period, the urbanization process in Ninh Kieu District takes place at a fast and strong pace. This has made it impossible for the urban drainage system to keep up with this change, thereby creating great difficulties for the drainage management here. In order to deal with these enormous challenges, the managers in this area need to incorporate new technologies into drainage management. This paper presents the main result of building a spatial database to support drainage management for Ninh Kieu District. This is considered as a fundamental source of data for application of GIS in urban drainage research and management in Ninh Kieu District.

Sensoriamento Remoto aplicado na Avaliação do Impacto do Armazenamento da Água de Chuva no Sistema de Drenagem Urbana

O processo de urbanização, com intensificação no número de construções, resulta na impermeabilização das superfícies na redução da infiltração e do escoamento subterrâneo, e consequente aumento do escoamento superficial. Neste contexto, pesquisadores buscam tecnologias para minimizar tais problemas ambientais, visando a melhoria não só da conjuntura atual, mas também das próximas gerações. Assim, se inserem as tecnologias verdes para mitigação dos problemas ambientais, com destaque para os telhados verdes. Tal cenário de crescimento urbanístico e de problemas ambientais é evidenciado nos grandes centros urbanos, a exemplo do município de Recife-PE, especificamente na Região Político Administrativa RPA2, no bairro de Dois Unidos. Para identificar áreas verdes e urbanizadas, foi empregada a tecnologia do Sensoriamento Remoto com o emprego do Índice de Construção por Diferença Normalizada (NDBI) e, para identificar os pontos baixos das vias e realizar a análise de alagamento foi utilizado o Modelo Digital de Elevação (MDE) com a geração das curvas de nível. Os resultados indicaram que as duas ações investigadas, telhados verdes e caixas d’água, conjuntamente, foram ineficientes na resolução dos alagamentos e que os custos da adaptação dos telhados para implantação das coberturas verdes foram mais onerosos que a aquisição de caixas d’água de 500 L. Por outro lado, tais ações podem contribuir para a redução das dimensões do projeto de drenagem urbana reduzindo o volume de água pluvial excedente (acima da capacidade de escoamento da sarjeta) em cerca de 45% (de 46.033,30 m3 para 20.902,23 m3). Remote Sensing applied to the Impact Assessment of Rainwater Storage in the Urban Drainage SystemA B S T R A C TThe urbanization process, with an increase in the number of constructions, results in the waterproofing of surfaces, reducing infiltration and underground runoff, and a consequent increase in surface runoff. In this context, researchers are looking for technologies to minimize such environmental problems, aiming to improve not only the current situation, but also the next generations. Thus, green technologies are included to mitigate environmental problems, with an emphasis on green roofs. Such a scenario of urban growth and environmental problems is evidenced in large urban centers, such as the municipality of Recife-PE, specifically in the Administrative Political Region RPA2, in the neighborhood of Dois Unidos. To identify green and urbanized areas, Remote Sensing technology was used with the use of the Normalized Difference Construction Index (NDBI) and, to identify the low points of the roads and perform the flood analysis, the Digital Elevation Model was used (MDE) with the generation of contour lines. The results indicated that the two actions investigated, green roofs and water tanks, together, were inefficient in resolving the floods and that the costs of adapting the roofs for the implementation of green roofs were more expensive than the purchase of water tanks from 500 L. On the other hand, such actions can contribute to reducing the dimensions of the urban drainage project by reducing the volume of excess rainwater (above the drainage capacity of the gutter) by about 45% (from 46,033.30 m3 to 20,902.23 m3).Keywords: urban drainage, green roof, water tanks.

Integrated and Control-Oriented Simulation Tool for Optimizing Urban Drainage System Operation

With the management and operation of urban drainage systems (UDS) becoming more complicated and difficult, integrated models aiming to control and manage the entire drainage system are under enormous demand. Ideally, integrated models, as a potential tool for meeting the increasing demands, should combine both conceptual and mechanistic models that merge all UDS components and balance simulation accuracy with time constraints. Within this context, our study introduces an innovative modeling software, Simuwater, which couples multiple principles, simulates multiple components, and combines optimized control functions, playing a role in the integrated simulation and overflow control application of UDS. The software has been utilized in a real-time case-control study in one city of China, and it obtained significant optimized operation results to reduce combined sewer overflow (CSO) by making full use of the storage facilities and actuators. As the Simuwater model continues to improve in depth and breadth, it will play an increasingly important role in more application scenarios of UDS.

Urban Flood Risk and Economic Viability Analyses of a Smart Sustainable Drainage System

Urban drainage systems are in transition from functioning simply as a transport system to becoming an important element of urban flood protection measures providing considerable influence on urban infrastructure sustainability. Rapid urbanization combined with the implications of climate change is one of the major emerging challenges. The increased concerns with water security and the ageing of existing drainage infrastructure are new challenges in improving urban water management. This study carried out in the Seixal area in Portugal examines flood risk analyses and mitigation techniques performed by computational modelling using MIKE SHE from the Danish Hydraulic Institute (DHI). Several scenarios were compared regarding flood risk and sustainable urban drainage systems (SuDS) efficiency. To obtain a more accurate analysis, the economic viability of each technique was analyzed as well through (i) life cost analysis and (ii) taking into account the damages caused by a certain type of flood. The results present that the best scenario is the one that will minimize the effects of great urbanization and consequently the flood risk, which combines two different measures: permeable pavement and detention basin. This alternative allows us to fully explore the mitigation capacity of each viable technique, demonstrating a very important improvement in the flood mitigation system in Seixal.