The existing hydrodynamic models consider full physics approaches to calculate storm surge at coastal regions. However, due to the complexity of the equations that model these processes, the computational time and power required to run them can be large, compared to models that consider simplified equations. By contrast, simplified hydraulic models lack physical background, what leads to a minor accuracy in the surge estimations with respect to hydrodynamic models. In this project, a stochastic model has been developed with the objective to estimate surge at the coast of Mississippi (United States) at a reasonable accuracy and time, without solving equations that represent complex physical processes. The stochastic model needs to be trained by means of hurricane data, including surge levels. This information must be generated beforehand, by simulating a limited number of hurricanes with an hydrodynamic model. In this project, the hydrodynamic model Delft3D Flexible Mesh has been used for this purpose. The approach followed to build the stochastic model has been based on three main steps. The first step has been setting up and validating the hydrodynamic model in Delft3D FM. Hurricane Katrina (2005) has been simulated to calibrate the input parameters of the model, by comparing the maximum simulated water levels at 41 stations along the shoreline of Mississippi to the high water marks observed at the same locations during the event. Tide, surge and wave setup have been considered in the validation. The results of the validation show a line best fit slope from the origin of 0.912 and an R-squared of 0.996. At Gulfport, the absolute error of the surge estimation is 19 centimeters, equivalent to a relative error of 2.5%. The second step in the construction of the stochastic model has been the generation of a historical hurricane data base. The hurricane best tracks have been retrieved from the HURDAT2 data base. The variables considered have been the forward speed and the forward direction of the hurricane at landfall, the wind speed at landfall, the distance from landfall location to a reference point (Galveston Bay) and the maximum storm surge during the hurricane. In this case, only the hurricane forcing is considered as external action. The storm surge has been recorded at Gulfport Harbour (central coast of Mississippi). The values of the surge have been obtained by using the validated model to simulate the historical hurricanes making landfall in a rectangular domain of 600 kilometers, being Gulfport Harbour the center of the rectangle. Due to the scarce number of hurricanes making landfall in this region, the tracks of the hurricanes making landfall in the North of the Gulf of Mexico but outside the rectangular domain have been shifted inside the domain, in order to generate a sufficiently large data base to train the stochastic model. A data base with 140 hurricanes has been built, from which the 85% (119 hurricanes) have been used for the training of the stochastic model and the other 15% (21 hurricanes) have been used for the validation of the stochastic model. The third and last step has been the setup and validation of the stochastic model, by comparing the storm surge obtained from the stochastic model to the surge obtained from the hydrodynamic simulations. The stochastic model used to estimate storm surge has been a Bayesian Network that assumes normal copulas to represent the joint distribution between nodes of the network. The calculated slope of the best fit line for the mean surge values has been 0.861, with an R-squared of 0.885. Moreover, the average standard deviation of the estimations is 1.16 meters. These results indicate a reasonable estimation of the surge by means of the Bayesian Network. This estimation can be made in the order of seconds. ... Read more

Rapid urbanisation and globalisation are bringing increasingly complex issues to the forefront. Improper planning of human activities and over exploitation of the surrounding natural resources has successfully damaged the biodiversity and the natural processes. Today humanity is at a stage where these ecosystem services are essential for our existence but the resources have been exploited beyond their capacity. In addition, climate change adds additional long-term threats due to erratic weather patterns and extreme natural events. Coastal Lagoons are one such geographical feature where such complexities are very visible. Given the high fertility of the surrounding land and the biodiversity hosted by the lagoons, they are rich resource banks for settlements to thrive on. This has led to issues like water pollution, loss of biodiversity and urban encroachment. Despite protection from the international communities like the Ramsar Convention, most wetlands are degrading everyday. The need of the hour is to find innovative middle ground solutions, where the services can be availed without degrading the environment. Further, to plan these services in a way that they are instrumental in reviving and enriching the lost ecosystem. This project attempts to present on such design and strategy for the Muni-Pomadze Lagoon (MPL) in Ghana. Considering the complexity of the issues, the project chose a interdisciplinary and collaborative approach to produce a holistic solution for the site. Further, it uses the principles of Nature-Based Design and 4-P framework (People, Planet, Prosperity and Project) to guide and reflect on the design. (van Dorst & Duijvestein 2004) This report attempts to contribute to the research on interdisciplinary design processes. Further, it aims to be a starting point and guideline for the Forestry Commission and Municipal body of Winneba, for better conservation of the Muni Lagoon. ... Read more

In the recent years, several cases of flash floods have been reported in the Municipality of Tirana, causing important material damage in the region. One of the most devastating events occurred in December 2017, which flooded the City Park area (West of the Municipality of Tirana). This area is strategical because it includes relevant centers of economic development, such as commercial and industrial areas, that are located nearby a main road connection between the Port of Durres, the Tirana International Airport and Tirana itself.  To mitigate the flood risk at this location, several hydraulic engineering concepts have been developed. However, the suitability of the concepts is limited by two main constraints: budget constraints and spatial constraints. With the aim to develop a flood protection system that is financially and spatially feasible, a system that combines dikes and flood walls is proposed. The industrial and commercial areas of the City Park are very close to the river. Hence, due to the spatial constraint, flood walls are used to protect these areas. Dikes are implemented in the river boundaries were agricultural and green land uses are found. Grass covers are implemented on the dike slopes to compensate the impact provoked by the water retaining structures in the local environment. The grass enhances the local visual amenity. Furthermore, bike paths are implemented on the dike crests and contiguous to the flood walls to improve the livability of the area.  In order to adapt further to the budget, the dimensions of the structures to be built are reduced by dredging the river beds, what increases the section of the river to convey water. A granular filter is placed on the river bed in order to reduce the soil erosion. Moreover, in order to reduce the financial and visual impact of the dikes, temporary structures of one meter height will be placed on the crest of the dikes in case a 100-year flood event occurs. A Cost-Benefit Analysis (CBA) of the proposed solution has been carried out to evaluate the feasibility of the alternative. The resultant BC ratio of the solution is 0.84, which is close to what is considered feasible (BC > 1). However, this ratio is sensitive to the discount rate. According to the falling tendency of this rate in Albania in the recent years, as shown by the information published by the Central Bank of Albania, the rate is expected to fall from 1.25% to 1% in the close future. This drop would make the project feasible (BC = 1.05 > 1).  ... Read more

The 2011 Great East Japan Earthquake had a devastating impact on the town of Otsuchi in Iwate Prefecture, resulting in 1,234 immediate deaths and 59.6% of residential houses being fully damaged amongst other severe consequences. The post-disaster Reconstruction Plan (2011-2018) of this town focused on rebuilding the previously existing town with large-scale engineered interventions, resulting in a fragmented set of spatial interventions which solve problems in a single faceted way. The management of a post-tsunami reconstruction process should represent a resilient design for the future. This paper demonstrates that a modified land use design, developed and achieved through an interdisciplinary approach, represents a holistic solution to the drawbacks of the reconstruction plan. Through an iterative framework, site-specific strategies are developed at the urban and the building scale that combine safety and livability by finding synergies among disciplinary fields in an integrated manner. The result of this paper is a quantified evaluation of the reduction in flood risk achieved with a new design, making spatially evident the areas in which a refinement is required to mitigate flood damage.
Subject: tsunami; interdisciplinary; resilience; spatial planning; strategy
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From the 26th to the 30th April 2018 a group of students from TU Delft travelled to Albania to analyze the management of flooding events in the municipality of Tirana, Albania. The scope of the workshops organized was gaining a better insight in the
interaction between public and private parties in the interventions as a response to floods. ... Read more