High-water levels in the Rhine-Meuse delta are going to rise in the upcoming decades due to climate change with the accompanied sea level rise and the increase of the frequency of extreme Rhine discharges. The flood prone areas not protected by flood defenses at the Island of Dordrecht are directly influenced by the increase of these high-water levels, leading to an increase in the future flood risk. To lower this risk, the Delta21 project has been proposed. By pumping water from the Haringvliet, the high-water levels in the delta are lowered. It is unclear if an optimal operation of Delta21 for the flood prone areas of Dordrecht exists and if the reliability of the project impacts this high-water level reduction.

The main objective of this report is to determine if the inclusion of Delta21 to the flood protection system of the Rhine-Meuse delta can provide a significant reduction of the flood risk of the flood prone areas at Dordrecht. Furthermore, it should be determined if an optimal operational scheme is possible in which the flood protection system with Delta21 can comply with all the flood requirements of the flood prone areas at Dordrecht and limitations to the Europoort barrier and Delta21 project while considering the reliability of the Delta21 project and the climate scenarios of the year 2100.

It was determined that the present flood risk at the flood prone areas at the Island of Dordrecht is equal to €110,000 per year. For the minimum, medium and maximum scenario for the year 2100 this risk increases to €390,000, €1,300,000 and €8,100,000 per year respectively. The implementation of the optimal operation of Delta21 reduces this risk with 23, 15 and 64 %. To obtain a flood risk reduction of 64 % for the maximum scenario, the closure frequency of the Europoort barrier, which may not be larger than three times per year, is equal to ten times per year. Furthermore, the flood risk as a percentage of the average annual income per household at the flood prone areas may not exceed 1 %, but for the medium onward this limit is exceeded at the historical harbor (city center). The maximum allowable probability of failure per pump of the pumping station and per siphon of the spillway of Delta21 is about 0.5 if the correlation between the components of both these systems is smaller than 0.9.

The inclusion of Delta21 in the current flood protection system with the present Europoort closure level can provide a significant reduction of the future flood risk of the flood prone areas at Dordrecht. However, it is not possible to create an optimal operational scheme for all scenarios of the year 2100 in which the flood protection system with Delta21 complies with the flood requirements of the flood prone areas and the limitations of the Europoort barrier. Finally, the reliability of the new Delta21 components is non-decisive for the flood risk assessments that have been made as long as the components are not fully dependent.
... Read more

The central Thermo Electrico Antonio Guiteras (CTE Antonio Guiteras) is a thermoelectric power plant located in the bay of Matanzas. In 2017, hurricane Irma passed the north coast of Cuba and destroyed the primary sea defense in front of the CTE, causing major damage to the plant. The power plant is renovated, and a new and improved sea defense is currently being constructed.
The goal of this report is to answer the following question: to what extend is the power plant protected during extreme weather conditions and what improvements are needed to ensure that the power plant can remain operational during these extreme weather conditions?
To determine what the hydrodynamic and meteorological effects are of a extreme weather event such as a tropical cyclone, a synthetic tropical cyclone is created. This synthetic hurricane must generate large significant waves in combination with a big storm surge, to have severe impact on the CTE. It must also have a significant probability of occurrence. To determine this normative synthetic hurricane, multiple synthetic hurricanes are simulated in Delft3D and XBeach and their corresponding return period is determined. As Irma significantly damaged the CTE, this hurricane is taken as the basis for all synthetic hurricane combinations. The hurricanes each vary from Irma in maximum wind velocities, forward speeds and their tracks.
To simulate the physics of hurricane Irma, a spiderweb grid is created at the locations of the hourly best track of Irma. This is then used in the Delft3D model as input for the pressure and wind fields of the hurricane. The output of the Delft3D model is validated with recorded data of observations stations in the Gulf of Mexico. Recorded water levels and wind speeds of buoys near Key West are used for validation. XBeach is used to simulate the nearshore physical processes. XBeach can more accurately predict wave propagation and includes higher order processes in its simulation. As input for the XBeach model, the output of the Delft3D model is used.
After running all the synthetic hurricanes in Delft3D, the five resulting normative hurricanes are run in XBeach. The synthetic hurricane that creates the largest significant wave heights at the project area is taken as a basis for the final design. This normative hurricane gives a maximum significant wave height of 8.8 m with a corresponding storm surge of 1.61 m at the location of the CTE.
With these values a research on the current defense wall is done. Ultimately for a part of the sea defense an adjustment on the existing defense wall is proposed. A second but lower vertical wall with a bigger bullnose is placed in front of the existing one. This creates a triangular shaped stilling basin, from which the water can flow out at the seaside of the wall. For the other part of the sea defense no adjustments on the wall are proposed but an improvement of the existing drainage capacity is proposed. The existing drainage channel, which lies behind this section, is widened and deepened. Additionally, a drainage wall is built around the powerplant, which diverts the overland flow caused by intense rainfall into the drainage channel.
... Read more