Engineering with Nature: an innovative solution for coastal erosion protection

Programa doutoral em Engenharia CivilCoastal zones are a much-appreciated environment by society, and support a large amount of economic and leisure activities. Growing demographic pressure on these very special territories that are associated to rapid economic growth and coastward migration has resulted in significant infrastructure and assets located in risk-prone areas, increasing exposure and vulnerability to natural disasters along the coast, including erosion, flooding and salt intrusion. In these areas, sediment transport and erosive processes are worldwide critical aspects for territory planning and management, especially in countries with long coastline like Portugal, since these phenomena often endanger human life and property protection. A research effort is still needed to find more robust and nature-based protection solutions adequate for high energetic coastal environments. The design, construction and maintenance of coastal protection structures incorporating principles of resilience to climate change impacts require a comprehensive multidisciplinary scientific approach for a deep understanding on coastal hydromorphodynamics and on the behaviour of new eco-materials in marine environments. In this research work different methodologies were applied to describe: (i) wave climate regimes under uncertainty of climate changes scenarios off Iberian Peninsula coast; (ii) coastal hydro-morphology dynamics applying numeric modelling tools; and (iii) thermo-mechanical behaviour of an innovative eco-engineering solution for recycled steel fibre reinforced concrete armour unit. The main outcomes of this research are: (i) the determination of 10-, 50-, and 100-year return period of significant wave height and wave peak period values that can be used with confidence as design parameters for structural analyses in maritime works to be built in the western coast off Iberian Peninsula; (ii) results of a comparative study on coastal protection structures to promote wave energy dissipation and sediments retention; (iii) the proposal of an optimized geometry of maritime structures under longitudinal drift reversal conditions based on hydro- and morphodynamics modelling; (iv) a deep study on thermo-mechanical behaviour of a recycled steel fibre reinforced concrete armour unit; and (v) the proposal of an innovative ecoengineering solution for breakwater armour incorporating the new scientific achievements. Globally, this research work aims at the design and assessment of innovative nature-based coastal engineering solutions based on modelling and observation of natural accretion or sedimentary stable processes, and the application of high structural multifunctional eco-materials with high durability and ductility tested through numerical modelling.A crescente pressão demográfica sobre as zonas costeiras, associada ao rápido crescimento económico e à migração de pessoas para o litoral, tem tido como consequência a implantação de infraestruturas e ativos significativos em áreas propensas a riscos, aumentando a exposição e a vulnerabilidade a desastres naturais ao longo da costa, incluindo erosão, inundações e intrusão salina. O transporte de sedimentos e os processos erosivos nestas áreas constituem aspetos críticos para o ordenamento e gestão do território, especialmente em países de costa extensa como Portugal, uma vez que estes fenómenos colocam frequentemente em risco a vida humana e a proteção de bens. O projeto, construção e manutenção de estruturas de proteção costeira baseadas na natureza em ambientes altamente energéticos, incorporando princípios de resiliência aos impactos das alterações climáticas, requerem uma abrangente abordagem científica multidisciplinar para a compreensão da hidro-morfodinâmica costeira e do comportamento de novos eco-materiais em ambientes marinhos. Neste trabalho de investigação, foram aplicadas diferentes metodologias para descrever: (i) regimes de agitação marítima em cenários de incerteza provocados por alterações climáticas na costa da Península Ibérica; (ii) modelação da dinâmica da hidro-morfologia costeira; e (iii) comportamento termo-mecânico de uma solução inovadora de eco-engenharia para blocos de mantos de quebramar em betão reforçado com fibras de aço reciclado. Os principais resultados deste trabalho de investigação são: (i) a determinação do período de retorno de 10, 50 e 100 anos para a altura de onda significativa e para valores de período de pico de onda que podem ser aplicados com confiança como parâmetros de projeto para análises estruturais em obras marítimas a construir na costa ocidental da Península Ibérica; (ii) resultados de um estudo comparativo de estruturas de proteção costeira para promover a dissipação da energia das ondas e a retenção de sedimentos; (iii) a proposta de uma geometria otimizada para estruturas marítimas sob condições de inversão longitudinal da deriva com base em modelação hidro-morfodinâmica; (iv) um estudo aprofundado sobre o comportamento termomecânico de blocos de mantos de quebramar em betão reforçado com fibras de aço reciclado; e (v) a proposta de uma solução inovadora de eco-engenharia para mantos de quebramar, incorporando os novos resultados científicos obtidos. Em resumo, este trabalho de investigação visa o projeto e avaliação de soluções inovadoras de engenharia costeira baseadas na natureza, através de modelação e observação de processos estáveis de acreção natural ou sedimentar e a aplicação de eco-materiais multifuncionais de alta durabilidade e ductilidade testados através de modelação numérica.Portuguese Foundation for Science and Technology - PhD scholarship SFRH/BD/141381/2018

Technological platform for catchment water safety planning

Water safety plans is a concept proposed by the World Health Organisation for risk assessment and risk management in drinking water systems. This concept includes the identification of hazards and control points throughout the water cycle from the catchment to the point of consumption. Deterioration in surface and groundwater quality due to sources of pollution impacting the water intake should be identified and monitored allowing effective management and operation of drinking water systems. Land use information, monitoring databases, and hydrodynamics and water quality river modelling can be used to estimate and forecast the spatial and temporal mass transport and attenuation hazards that impact a given drinking water intake. This work presents a technological platform based on the Delft-FEWS software in which databases and models were implemented for supporting catchment water safety plans in different river basins of the NW region of Portuga

Technological platform for catchment water safety planning

Water safety plans (WSP) is a concept introduced by the World Health Organisation (WHO, 2004) for risk assessment and risk management in drinking water systems. This approach has been increasing embraced by water suppliers, governments and other stakeholders. Raw water quality is a key factor for ensuring good and safe drinking water. Water use, land use and polluting human activity in the catchment area all have significant impacts on surface and groundwater quality, and thus the level and complexity of treatment plants necessary to ensure that the water leaving the works is safe and acceptable to consumers. Protection of raw water sources should be seen as the first, and often the most important, barrier to prevent microbial, chemical and radiological contamination of drinking water sources (Vieira et al., 2011). Due to continuously emerging threats to the drinking water quality from organic matter, pesticides, fertilizers, pharmaceuticals, trace metals, and other types of contaminants, much effort has been put in the development of knowledge that is capable to effectively identify potential risks. Information on catchment characteristics (e.g. geology, hydrology, meteorology, land use, competing water uses), surface water bodies (e.g. flow rate, water quality and seasonality) and groundwater (e.g. aquifer flow rate, flow direction and aquifer vulnerability to pollution) and application of models to quantify the spatial and temporal dynamics of transport and attenuation of hazards that arise from the pollution sources across a catchment are of paramount importance for evaluating and prioritizing risks in raw water sources (Vieira & Pinho, 2014; WHO, 2016). This paper presents the use of the Delft-FEWS platform (Werner et al., 2012) in implementing an early warning system supported by proper hydrodynamics and water quality models for supporting catchment water safety plans in two river basins of the NW region of Portugal

Integrating hydraulic modelling and GIS for wastewater systems management: a case study

The increasing costs related to operation and maintenance of urban wastewater systems has led to a special attention of utilities in promoting studies to address the key problem of water infiltration, inflow and improper connections entering the separate drainage networks. This is a common and hard to predict operational situation that needs to be identified and minimized as it negatively affects the managerial conditions of the network and the downstream wastewater treatment plant (WWTP) efficiency. Management difficulties in separate drainage networks seldom occur when unexpected groundwater inflow, stormwater infiltration, and flows from improper connections enter into the dedicated sanitary sewer systems. Although the consequences that improper flows may have on wastewater systems are known, the problem is difficult to locate and quantify. The use of modelling tools is of special relevance to the planning, management and rehabilitation of these types of systems, which can be very useful for: (i) evaluating the capacity of existing systems in real time; (ii) testing alternative solutions to solve problems detected; or testing different procedures to operate the systems in extreme events scenarios. The implementation of mathematical models for determining the hydrodynamics behaviour of dry-weather and wet-weather flows in sewers was applied in a small urban wastewater network of the city of Braga in Portugal (Figure 1). The free user program US EPA SWMM was applied with the integration of GIS InterAqua information related to the wastewater collection system

Integrating hydraulic modelling and GIS for wastewater systems management: a case study

The increasing costs related to operation and maintenance of urban wastewater systems has led to a special attention of utilities in promoting studies to address the key problem of water infiltration, inflow and improper connections entering the separate drainage networks. This is a common and hard to predict operational situation that needs to be identified and minimized as it negatively affects the managerial conditions of the network and the downstream wastewater treatment plant efficiency. The implementation of mathematical models for determining the hydrodynamics behaviour of dry weather and wet weather flows in sewers appears to be a sound methodology to identify the causes for those adverse management conditions. This methodology was applied in a small urban wastewater network of the city of Braga (Portugal). The free user program USEPA SWMM was applied with the integration of GIS information related to the wastewater collection system

Modelling of sanitary sewer systems integrating rainfall-derived infiltration and inflow

Wastewater utilities often have management difficulties when excessive wet-weather flow leads to serious impacts in public health and environment as well as disturbing operational conditions in wastewater treatment plants (WWTP). This phenomenon, resulting from rainfall-derived infiltration and inflow (RDII), occurs mainly due to defects in pipes and manholes (infiltration) and to illicit connections from downspouts, foundation drains or cross-connections with storm sewers (inflow), contributing to sanitary sewer overflows (SSOs). These difficulties related to SSOs negatively affect: (i) the capacity and operation of sanitary sewer collection; (ii) the performance and treatment efficiency of WWTP; (iii) the risk of a public health hazards and environmental contamination. This well-known wastewater managerial problem is very difficult to locate and quantify in practice since the needed adequate measurement equipment often entails unsustainable costs for utilities. Wastewater flow mathematical modelling integrating a digital cadastral database using Geographic Information Systems (GIS) constitutes a sound methodology in predicting sanitary sewer systems performance which is a critical issue within SSOs reduction and remediation programs. This paper presents the implementation of a methodology based on hydroinformatic tools to determine the contribution of RDII in complex municipal sewer systems in order to establish adequate urban wastewater management policies that will effectively mitigate SSOs. USEPA SWMM, and digital cadastral database with field verification were applied in a simulation study of the small scale sanitary sewer network of Espinho (Braga, Portugal) whose results will be used in a larger scale to create a city-wide model for wastewater systems management

Modelling of Sanitary Sewer Systems integrating Rainfall-Derived Infiltration and Inflow

Municipal wastewater management difficulties may occur when excessive wet weather flow determine sanitary sewer overflows (SSOs) mainly caused by the contribution of rainfall-derived infiltration and inflow (RDII) into sanitary sewers. This excess of wet weather flow can lead to serious problems to public health and environment as well as to suboptimal operation of wastewater treatment plants. This paper presents the implementation of a methodology based on hydroinformatic tools to determine the contribution of RDII in complex municipal sewer systems in order to establish adequate urban wastewater management policies that will effectively mitigate SSOs. USEPA SWMM, and digital cadastral database with field verification were applied in a simulation study of a small scale sanitary sewer network whose results will be used in a larger scale to create a city-wide model for wastewater systems management

Application of Delft3d for designing and assessing new solutions to improve sediment input to an erosion prone coast

The construction of harbor defense structures changes the natural sedimentary fluxes that contribute to feed the coastal drift in the adjacent beaches, in many harbors of the world located at river mouths. This paper presents a numerical modelling work, based on the Delft3D software, to study morphodynamics at the river Lima estuary, Portugal. This model was implemented recurring to a hydroinformatic environment that was constructed at University of Minho along the last two decades. Considering specific hydrodynamic conditions and typical characteristics of the estuarine sediments, the capacity of hypothetical structures to improve transport of sediments to the coast was assessed: (i) a submerged transverse non-erodible dam and (ii) an emerged groin linked to the left embankment located at the upstream section of the harbor. The implemented hydroinformatic environment presents capacities to simulate the complex morphodynamic behavior of river mouths. The preliminary results reveals that the proposed structures can have a positive impact throughout dredging works facilitation by transferring depositional areas during flood events to a location near the coast inside the harbor. Ongoing field acquisition data will be essential to validate depositional patterns under different river discharges and wave conditionsPOCTEP/Interreg, project MarRISK (0262_MarRISK_1_E)info:eu-repo/semantics/publishedVersio

Obras de defesa costeira: potencialidades de inovação

Os processos erosivos em zonas costeiras são uma ameaça para os territórios litorais, exigindo um assertivo planeamento, uma vez que estes fenómenos colocam frequentemente em risco vidas humanas e a segurança e funcionalidade de infraestruturas. As abordagens tradicionais de engenharia de defesa costeira, como esporões, quebramares e obras aderentes, apresentam grandes desafios em termos de eficiência e de eficácia, devido, sobretudo, às dificuldades na sua construção e aos elevados custos de manutenção envolvidos. Por outro lado, estas soluções tradicionais apresentam vários tipos de fragilidades, salientando-se a perda de eficiência quando a deriva litoral de sedimentos diminui (esporões) e a erosão local agravada devida a modificação dos regimes de propagação de ondas (quebramares e obras aderentes). Da observação do funcionamento de sistemas costeiros artificiais e naturais, pode-se encontrar soluções técnica, económica e ambientalmente mais eficientes. Deste modo, poder-se-ão melhorar as soluções de defesa tradicional ou propor soluções inovadoras adequadas a climas de agitação energéticos. Neste trabalho, apresentam-se soluções de defesa que têm vindo a ser utilizadas em diferentes locais e cuja conceção resulta de adaptação de processos observados na natureza. Dar-se-á destaque à caracterização das condições que favorecem processos de acreção costeira que têm lugar de modo natural, e caracterizam-se materiais com características apropriadas a utilização em meios marinhos. A metodologia de procura de soluções mais robustas para a protecção dos ambientes costeiros baseia-se num laboratório numérico que permite a utilização de ferramentas de modelação morfodinâmica na avaliação do seu desempenho e que será também caracterizado neste trabalho

Análise comparativa do desempenho de uma estrutura inovadora de proteção costeira baseada na Natureza com o de uma estrutura tradicional

As soluções tradicionais de engenharia têm demonstrado fragilidades na mitigação dos processos erosivos em zonas litorais vulneráveis, contribuindo, em alguns casos, para o seu agravamento. No presente trabalho, apresentam-se resultados de modelação hidro-morfodinâmica de um estudo comparativo do desempenho de uma estrutura marítima inovadora com o de uma estrutura tradicional (esporão), em condições de tempestade. A estrutura inovadora contempla uma geometria otimizada, baseada na natureza, que garante a dissipação de energia das ondas e a retenção de sedimentos através de condições de inversão da deriva litoral. O ambiente hidroinformático para simulação de processos costeiros é desenvolvido com base nos programas Delft3D e SWAN para a análise da propagação da agitação e XBeach para a análise da morfologia resultante na envolvente de cada uma das estruturas e ao longo da costa. Os resultados da modelação hidro-morfodinâmica demonstram que, junto à costa, contrariamente ao que acontece com o esporão (solução tradicional estudada), a estrutura inovadora contribui para a acumulação de sedimentos a sotamar, uma vez que não há interrupção da deriva litoral. Além disso, a sua localização intertidal integra um aspeto positivo para a promoção da biodiversidade