Evaluation of the feasibility of solutions to flash flooding in the municipality of Tirana (Albania)

Evaluation of the feasibility of solutions to flash flooding in the municipality of Tirana (Albania)

Prida Guillén, Álvaro (TU Delft Civil Engineering and Geosciences; TU Delft Hydraulic Structures and Flood Risk)

Voorendt, Mark (mentor)
Hoes, Olivier (graduation committee)

Delft University of Technology

Civil Engineering | Hydraulic Engineering

2019-06-18

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). 

Flash floods
Flood Risk
Design methodology
Albania

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© 2019 Álvaro Prida Guillén