Morphological Impact of Coastal Structures Student: Remco van der Hoeven Studentno.: 9347290 December, 2010 Hydraulic Engineering Group Hydraulic and Geotechnical Engineering Division Faculty of Civil Engineering and Geotechnics Delft University of Technology Morphological Impact of Coastal Structures Contents Contents Abstract ..................................................................................................................................... 1 1. Introduction ....................................................................................................................... 2 1.1. Introduction to this report .................................................................................................... 2 1.2. Objectives of the report ....................................................................................................... 3 1.3. Outline of the report ............................................................................................................ 4 2. Background of erosion problems ..................................................................................... 7 2.1. Introduction ......................................................................................................................... 7 2.2. Structural erosion ................................................................................................................ 8 2.3. Erosion during (severe) storm surges .................................................................................. 8 3. Introduction to the cases ................................................................................................ 10 3.1. Overview of the used symbols in the cases ....................................................................... 10 3.2. Schematisations ................................................................................................................. 10 3.3. Determination of the cases ................................................................................................ 13 4. Case 1: Structural erosion: 200,000 m3/y IN – 300,000 m3/y OUT ............................. 15 4.1. Description of the problem ................................................................................................ 15 4.2. Cause of this problem ........................................................................................................ 16 4.3. Solution to the erosion problem ........................................................................................ 16 4.4. The use of groynes ............................................................................................................ 18 4.5. The use of offshore breakwaters ........................................................................................ 19 4.6. The use of seawalls or dune revetments ............................................................................ 20 4.7. Remarks on this case ......................................................................................................... 20 5. Case 2: Structural erosion: 500,000 m3/y IN – 600,000 m3/y OUT ............................. 22 5.1. Description of the problem ................................................................................................ 22 5.2. Cause of the problem ......................................................................................................... 22 5.3. Solution to the erosion problem ........................................................................................ 23 5.4. The use of groynes ............................................................................................................ 23 5.5. The use of offshore breakwaters ........................................................................................ 24 5.6. The use of seawalls or dune revetments ............................................................................ 24 5.7. Remarks on this case ......................................................................................................... 24 6. Case 3: Structural erosion: 0 m3/y IN – 100,000 m3/y OUT ........................................ 26 6.1. Description of the problem ................................................................................................ 26 6.2. Cause of this problem ........................................................................................................ 26 6.3. Solution to the erosion problem ........................................................................................ 28 6.4. The use of groynes ............................................................................................................ 28 6.5. The use of offshore breakwaters ........................................................................................ 29 6.6. The use of seawalls or dune revetments ............................................................................ 30 6.7. Remarks on this case ......................................................................................................... 30 7. Case 4: Structural erosion: 200,000 m3/y IN – 300,000 m3/y OUT (increased wave height) ...................................................................................................................................... 31 7.1. Description of the problem ................................................................................................ 31 7.2. Cause of the problem ......................................................................................................... 31 7.3. Solution to the erosion problem ........................................................................................ 31 7.4. The use of groynes ............................................................................................................ 32 7.5. The use of offshore breakwaters ........................................................................................ 32 7.6. The use of seawalls or dune revetments ............................................................................ 32 7.7. Remarks on this case ......................................................................................................... 32 8. Case 5: Structural erosion: Seasonal differences ......................................................... 33 8.1. Description of the problem ................................................................................................ 33 8.2. Cause of the problem ......................................................................................................... 34 8.3. Solution to the erosion problem ........................................................................................ 34 8.4. The use of groynes ............................................................................................................ 34 Morphological Impact of Coastal Structures Contents 8.5. The use of offshore breakwaters ........................................................................................ 34 8.6. The use of seawalls or dune revetments ............................................................................ 35 8.7. Remarks on this case ......................................................................................................... 35 9. Case 6: Structural erosion: Wide surf zone, transport seawards side ....................... 36 9.1. Description of the problem ................................................................................................ 36 9.2. Cause of the problem ......................................................................................................... 36 9.3. Solution to the problem ..................................................................................................... 37 9.4. Remarks on this case ......................................................................................................... 39 10. Case 7: Structural erosion in combination with a tidal current ............................. 40 10.1. Description of the problem ................................................................................................ 40 10.2. Cause of the problem ......................................................................................................... 40 10.3. Solution to the erosion problem ........................................................................................ 40 10.4. The use of groynes ............................................................................................................ 41 10.5. The use of offshore breakwaters ........................................................................................ 42 10.6. The use of seawalls or dune revetments ............................................................................ 42 10.7. Remarks on this case ......................................................................................................... 42 11. Case 8: Beach of insufficient width ............................................................................ 43 11.1. Description of the problem ................................................................................................ 43 11.2. Solution to the problem ..................................................................................................... 43 11.3. The use of various engineering tools ................................................................................. 44 11.4. Remarks on this case ........................................................................................................