# 工程设计作业代写 CVEN90051 CIVIL HYDRAULICS

## CVEN90051CIVILHYDRAULICS

Module 3: Coastal Hydraulics

Assignment 3

Assignment 3 (20 points)

deadline: 11.59pm on October 23rd, 2022

A report of about 1500-2000 words (i.e. a short document). There is no limit on the number of pictures/graphs/tables used, but make sure they are all properly introduced and                discussed in your report.

### Assignment  工程设计作业代写

The local council has decided to build a new marina and has commissioned the design of a new breakwater to your firm.

To support the design, the council has provided results from a recent assessment of the marine climate in the region. This study indicates that the design (100-year) storm event would reach its peak at about 350 km from the coast, with a significant wave height of 4m and a dominant wave period of 8s. The dominant wave direction, at the location of the storm, is expected to be about 39 degrees relative to a reference direction perpendicular to the beach (see Figure 1).

#### The tide*  is generally small at the location of the proposed marina, and the tidal variation across the still water level is about ±0.1m. At the time of the design, it is assumed that the storm surge# is negligible.

The  council   has  also   provided  the   bathymetry   (i.e.  water  depth)  through  the  files water_depth.mat (Matlab)  and water_depth.xlsx (Excel). In these files, the variable “x” is the distance from the beach, expressed in km, and “h” is the water depth, expressed in m. (Note that this bathymetry refers to the still water level and does not include the tidal excursion). In addition, The council has also advised that the sea floor material is primarily composed by sand. A recent geological survey has reported that the grain size corresponds to d50 = 1.5mm.  工程设计作业代写

The marina (see schematic in figure 1) will cover an area extending 240m along the coast and 340 m perpendicular to the coastline; it is connected to a sandy beach by a pier 150 m long (see Figure 1). To allow manoeuvring, 100m wide channels have to be considered. Overall, the total  surface  needed for the  marina  is 440m x  590m. Therefore, the  breakwater  is expected to extend over 600m from the beach.

* Tides are the rise and fall of the still water level caused by the combined effects the Moon and the Sun.

# The storm surge is an abnormal rise in sea level over and above the normal tide levels.

Figure 1: Schematic of the marina (note that the wave direction is the one at the storm

location, i.e. 350 km from the marina).

As there will be limited space between the breakwater and the berths, the local council has requested that overtopping does not exceed 20 l/s/m during the design storm. No specific request about the breakwater material were made. Therefore, you are free to select the material of your choice.

The assignment requires the design of the breakwater through the following tasks:

Estimate the design conditions at the  location of the  breakwater and  propose a suitable layout for the structure with approximated dimensions.

Design and verify performance of the cross-section of the breakwater.

A recent study published during the design process revealed that, as a result of climate change, the region has become subjected to storm surges, which can increase the water level to about 1.3 m above the still water line. Because of this new input, go back to your design and re- consider the water level changes due to the storm surge. If necessary, suggest modifications to the structure, without redesigning the whole breakwater (i.e. propose minimal changes)?

Compile and submit a report explaining (with text, figures, diagrams, tables, etc.) each task concisely and clearly. Ensure all initial conditions, assumptions, constraints, design ideas, etc., are clearly marked.