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.

RAINWATER MANAGEMENT PROBLEMS IN CITIES IN DEVELOPING COUNTRIES: THE CASE OF THE MUNICIPALITY OF ZIGUINCHOR, SENEGAL

Senegalese cities are experiencing very rapid growth in terms of both spatial and demographic development, which has an impact on the management of runoff water, which is increasingly a major concern of authorities and urban populations. In these cities, public sanitation infrastructure is insufficient and unevenly distributed in urban space. The objective of this study is to characterize the problem of rainwater management in the city of Ziguinchor (southern Senegal). The methodology is based on an administration, a questionnaire submitted to 288 heads of households, and an interview guide with 13 actors who stand out in the environmental management component at the local level. The results obtained attest to a real problem of sanitation of rainwater managed in precarious conditions due to the lack of infrastructure and water management methods used by households. The infrastructural problem is a factor in the poor management of rainwater in Ziguinchor, while rainwater drainage practices do not protect the living environment of the populations. In the city of Ziguinchor, the main strategies adopted in the face of the sanitation network deficit are based on backfilling, the laying of sandbags and stones, evacuation through buckets.

Innovative Ceramic Floor for Resilient Cities

LIFE CERSUDS is a project carried out over the period 2016-2019 whom the main objective was to improve the ability of cities to adapt to climate change by promoting the use of green infrastructures in the renewal of urban environments. Under the project, an innovative permeable urban pavement (hereinafter, CERSUDS) was designed using ceramic tile stock of low commercial value. This pavement solution was tested in a demonstrator in the town of Benicí ssim. The main objective of the project was to improve the ability of cities to adapt to climate change by promoting the use of green infrastructures in the renewal of urban environments. Under the project, a Sustainable Urban Drainage System (SUDS) was built as a demonstrator in the town of Benicí ssim, using ceramic tile stock of low commercial value to manufacture an innovative permeable floor (hereinafter, CERSUDS flooring), a subject already dealt with in an earlier presentation at this congress . Once the demonstrator had been built, a monitoring period was run between August 2018 and July 2019, which enabled both the CERSUDS floor and the demonstrator's value as a rainwater management system to be validated. This article presents the design process of the ceramic permeable pavement including the main results of the tests carried in the laboratory and the main results of the project relate to: environmental and economic assessment of the CERSUDS system, user's validation of the system, monitoring of the system's mechanical performance and permeability, and monitoring of the demonstrator's hydraulic response in terms of the quantity and quality of run-off water.

Water retention measures in the urban landscape and their impact on microclimate change

Water management in cities and villages is fraught with difficulties. Infrastructure systems that have been in use for a long time are deteriorating. In an urbanised landscape, appropriate rainwater management or blue green infrastructure (RWM or BGI) is the solution. The quality of water management is influenced significantly by urbanization. The higher the influence on the area’s hydrological cycle as an urbanised landscape develops without proper RWM, the greater the impact on the area’s hydrological cycle. The hydrology of the site reflects the changing environment of the area, as trees, meadows, and agricultural land, which captured and absorbed precipitation and created depressions in the area that temporarily held water, are being replaced by urbanised areas on a uniform slope with impermeable areas. Because the goal until recently was to drain rainwater from the urbanised area as rapidly as possible, the altered sites present the prospect of rapid conversion of rainwater into surface runoff of rainwater. The capabilities of currently utilised technical solutions in metropolitan areas, as well as the possibilities of their application, are discussed in this article. The paper focuses on the available literature on rainwater management by Slovak and foreign authors to get insight into the execution of measures in urban settings. The article’s major purpose is to provide appropriate rainwater management measures in the urbanised landscape based on characteristics deriving from the conditions in the study area and current understanding about rainwater management options.

The social control and rainwater management in Brazil / O controle social e a gestão das águas pluviais no Brasil

The aim of this article is to discuss the conflicts of jurisdiction between the different entities of the Brazilian Federation about water management, particularly since these were not determined by the resolutions of the 1988 Federal Constitution. Although the role of the different players involved was outlined in the Water Resources Law, it was only through the enactment of the Law on Basic Sanitation, updated in 2020, that the municipalities were given responsibility for the management of rainwater in Brazil. Rainwater management currently forms, or should form, a part of the municipal planning of basic sanitation and community involvement, together with transparency, is becoming a key principle underlying the new model of local governance. The adoption of sustainable techniques and non-conventional methods of water management, based on the concept of Low Impact Urban Design and Development (LIUDD), is serving as a model for the kind of rainwater management that can allow social control together with democratic participation and the decentralization of sanitation services.

Analysis of Water Retention Possibilities Based on Programs, Strategies and Selected Projects in Poland

A particularly important and topical issue in contemporary urban planning and urban design is to prevent the current climate threat. The scale of the problem and the forecast of the effects of climate change are shown in the publication of numerous research centers such as NASA and the IPCC. The Report of a temperature increase of 1.5 degrees relative to the preindustrial era has shaken public opinion, however, a less optimistic scenario assumes an increase of 3 degrees. Local governments often face the challenge of rapid and effective response to the effects of climate change. Adaptation strategies to climate change have been developed at the EU level since 2009, in which the so-called White Paper has been passed, recognized as one of the first documents to define goals and measures, and on the national (Polish) level from around 2010. On the basis of strategic documents and research of scientific institutions, many local government units adopt programs aimed at implementing specific solutions. In the light of climate reports, it turns out that one of the most sensitive areas to climate change is water management. Therefore, effective adaptation measures include those aimed at rational management of rainwater. As a result, there are created comprehensive adaptation programs focusing on various sectors of the economy. Some of them are based on elements such as: green infrastructure, support for biodiversity or the implementation of activities in the field of blue-green infrastructure and the idea of "sponge city". They have been analyzed by the authors in terms of their usefulness and compliance with higher level documents. The aim of the study was to look at what actions are undertaken by cities in order to implement adaptation postulates. Selected activities undertaken by local government units of the cities of Olsztyn, Bydgoszcz and Gdańsk were analyzed. For educational purposes there are prepared information brochures for investors, residents and officials. They present the available tools and methods for sustainable rainwater management and increasing the city's resilience to the effects of climate change by increasing retention based on natural-based solutions. Equally important are the projects themselves, which is why another objective of the research was to analyze the implementation for compliance with the stated goal of increasing the retained water and adaptation to climate change of the city. The research methodology is based on desk-research and indirect inventory. A representative example of the research carried out is the implementation of the programs: "Rainwater management systems in the city of Olsztyn" and „Expansion of the rainwater management system in the city of Olsztyn”. The authors conclude that the adopted programs and strategies, as well as the implemented investments, are examples of both beneficial measures to improve water retention in the city, but unfortunately, they are also examples of "tools" to raise funds for investments, there are many in which rainwater is treated as sewage and still go directly to the sewage system.

Alternative Engineered Soils and Seed Mixes Used for Seepage Troughs

Green Infrastructure measures such as seepage troughs are an integral part of sustainable urban rainwater management. In Austria, seepage troughs are currently almost exclusively produced with a 30 cm thick active soil filter passage made of topsoil. A standard seed mix is used as vegetation, which usually consists of only three different turfgrass species. During a three-year trial, engineered soils with improved properties (increased water storage capacity, infiltration rate and pore volume) were tested for their suitability as seepage troughs compared to topsoil. In addition to the standard turf seed mix, a flowering turf seed mix (34 species) and flowering meadow seed mix (53 species) were applied. The engineered and reference soils were analyzed for infiltration rate, vitality, cover ratio and inflorescence. The results were further assessed with the evaluation chart showing quantitatively the suitability of the tested soils for rainwater management. The investigations showed that engineered soils in combination with flowering meadow seed mix lead to the best results. Therefore, this type of vegetation for seepage troughs is recommended for future applications. The reference alternatives cannot be recommended.

Cement-Bonded Sub-Base Layers of Walkable and Running Structures for Rainwater Management

Sub-base layers of walkable and running road structures usually consist of a stable subsoil with sufficient load-bearing capacity under the surface layer itself in the form of concrete covers or prefabricated paving elements. Due to their load-bearing capacity, these sub-base layers are most often constructed using cement-bonded aggregate technology. The current hot topic of rainwater management brings opportunities for the construction of water-permeable structures with good water retention capacity. The retention capacity of such a structure can be ensured in ideal conditions by making this sub-base partially permeable and with an absorbent layer while maintaining its mechanical advantages. The experiment confirmed the possibility of producing cement-bonded sub-base layers using light porous aggregates based on expanded clays. The high absorption rate of the type of aggregate used is a good starting point for increasing the retention capacity of the entire system.