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BED, BANK & SHORE BED, BANK & SHORE PROTECTION - CHAPTER 1

Coast (littoral or coastal) is defined as where land and sea borders. [1] The exact boundary is called the coastline, but this factor is difficult to determine due to the influenceof the tide. The term "coastal zone" is also used to replace the coast because it refers to an area of occurrence of the interaction between sea and land. [2] Both terms can be used to refer to the geographic location or region; example, the west coast of New Zealand, or the East Coast and West coast of the United States....

thachthaoxanh

Faculty of Coastal Engineering Faculty of Coastal Engineering

BED, BANK & SHORE BED, BANK & SHORE PROTECTION PROTECTION

Lecturer: Pham Thu Huong Lecturer: Pham Thu Huong

Chapter 1 Chapter 1

INTRODUCTION INTRODUCTION

(3 class hours)

CONTENT CONTENT

1. General of Viet Nam coast

2. The impacts cause the damages on coastal line

3. Protect or not protect ?

4. Coastal protection structures

5. Working conditions and requirement with coastal

structures

6. How to look at protections ?

7. How to deal with protections ?

18May) Schedule 45B (15Jan –– 18May) Schedule 45B (15Jan

(cid:190) 15 Jan: Chapter 1 (cid:190) 22 Jan: Chapter 2 (cid:190) 29 Jan: Chapter 3 (cid:190) 05 Feb: Chapter 3 (cont.) (cid:190) 12 Feb: Tet holiday (cid:190) 19 Feb: Tet holiday (cid:190) 26 Feb: Chapter 4 (cid:190) 05 Mar: Chapter 4 (cont.) (cid:190) 12 Mar: Chapter 5

(cid:190) 19 Mar: Chapter 5 (cont.) (cid:190) 26 Mar: Chapter 6 (cid:190) 02 Apr: Chapter 6 (cont.) (cid:190) 09 Apr: Assignment (cid:190) 16 Apr: Chapter 7 (cid:190) 23 Apr: Chapter 7 (cont.) (cid:190) 30 Apr: ??? (cid:190) 07 May: experiment (cid:190) 14 May: Summary

1. General of Vietnamese Coast 1. General of Vietnamese Coast

Islands in Ha Long as breakwaters

Dong Chau beach (Thai Binh)

Beach at Tien Giang river mouth (Go Cong)

Sandy beach at Quang Binh

Rocky beach at Hai Van mountain pass

2. The impacts cause the damages 2. The impacts cause the damages on coastal line on coastal line

• Natural impacts:

- Winds, typhoons ⇒ bring sand land ward or sea ward

- Tides, salty water ⇒ erosion, rusted steel structures

- Currents ⇒ erosion, creation

- Waves ⇒ erosion, instability of coastal lines, damaging structures which protect bed, bank and shore

- Chemical impacts ⇒ structures are corroded

- Impacts of organisms

Erosion in Nam Dinh coast Erosion in Nam Dinh coast

Impacts of organisms on culvert wall (NamDinh)

Wave action (Nam Dinh sea dike – August 2006)

2. The impacts cause the damages on coastal line 2. The impacts cause the damages on coastal line

• Artificial structures impacts:

Hoa Binh dam

- Building dams, reservoirs ⇒ reduce sediment transport to down stream, cause coastal line erosion

2. The impacts cause the damages on coastal line 2. The impacts cause the damages on coastal line

• Artificial structures impacts:

Exploiting sand in Tan Ba, Dong Nai river

- Exploiting sand, grave, mineral resources ⇒ inadequate sediment supply

2. The impacts cause the damages on coastal line 2. The impacts cause the damages on coastal line

• Artificial structures impacts:

Mangroves,

Đầm Nại, Bình Thuận

- Deforesting, destroying mangroves ⇒ erosion, unstable coastal line

2. The impacts cause the damages on coastal line 2. The impacts cause the damages on coastal line

• Artificial structures impacts:

- Reclamations ⇒ unstable coastal line - Canal, culvert system ⇒ Coastal erosion - Navigation ⇒ damage bank protections

3. To protect or not to protect ? 3. To protect or not to protect ?

Floating houses in MeKong River

Protect what ? Protect what ?

- Protect residential area from flood-tides, storm surge

- Prevent wave actions, erosions, slide of the slope

- Other purposes: Navigation, hydraulic works, aquaculture, tourism, salt production, national defense.

- Prevent salt intrusion*

* don’t mention in this lecture note

- Prevent sedimentation at river mouths and obstacle on draining off flood away*

4. Coastal protection structures 4. Coastal protection structures

- Construction: Sea dikes, revetments, groins, breakwaters, close-dams, sea-walls, artificial dredging and creating, dams, culverts,…

- Non-construction: sand nourishments, mangrove forests, laws, policies, institutions, organization methods and managements; propaganda, education, convincing people…

5. Working conditions & 5. Working conditions & requirement with Coastal structures requirement with Coastal structures

- Working conditions of coastal structures:

• Coastal structures are under the powerful influence of waves, winds, tides, currents, uplift pressures, drifts…

• erosion, accretion

- Requirement with Coastal structures:

• Height (cid:198) Allow overtopping ỏ Not ?

• Stable

• satisfy other purposes

6. How to look at protections? 6. How to look at protections?

When and Where ?

Building codes in eroding coastal line

Hue