BED, BANK & SHORE BED, BANK & SHORE PROTECTION - CHAPTER 11 doc

18 Sebtember 2007TRƯỜNG ĐẠI HỌC THỦY LỢI Khoa Kỹ thuật Biển BED, BANK & SHORE PROTECTION Lecturer: Pham Thu Huong Email: Huong.p.t@wru.edu.vn... 18 Sebtember 2007Khoa Kỹ thuật Biển Envi

18 Sebtember 2007

TRƯỜNG ĐẠI HỌC THỦY LỢI

Khoa Kỹ thuật Biển

BED, BANK & SHORE

PROTECTION

Lecturer: Pham Thu Huong

Email: Huong.p.t@wru.edu.vn

18 Sebtember 2007

Khoa Kỹ thuật Biển

Environment

(3 class hours)

18 Sebtember 2007

TRƯỜNG ĐẠI HỌC THỦY LỢI

Khoa Kỹ thuật Biển

10.1 Introduction 10.2 Bed protections 10.3 Bank protections 10.4 Shore protections

there should be a good connection between land and water

• use of sustainable materials

So: vertical walls are certainly not good

ecological infrastructure

river as ecological connection

with stepping stones

Space requirements versus discharge capacity, nautical possibilities, ect.

species and dynamics

food chain relations

in a bank

hardly any exchange of

life is possible between land and water

crossing location for mammals

Exit for animals

planning and execution of steps

load and strength

Basic types of shoreline protection

filter tests for nature friendly

fascine mattress

Reed and waves

Damping of wave loads

0.8

1 1 exp 0.001

cos

T T

wave damping and roughness in reed

roots

as an armour against sliding

permissible flow duration on

grass cover

reinforced vegetation

Vegetation growing through rock

Armorflex with vegetation

Roots in jute

Roots and Enkamat

strip with aquatic plants behind a

wave reductor

Nautilus Aquaflora rolls

Nautilus Aquaflora rolls

exchange of water in strip due to

passage of a ship

Berm along a shore

erosion between groynes

Sandy shoreline along a river

cross section of a coast with

mangroves

Can Gio Natural reserve, Vietnam

A healthy Rizophora forest

Young Rizophora plants

Viet Nam, Phu Loc ilsand

A Rizophora seedling

Avicennia forest

Southern Vietnam

Avicennia

Avicennia

Avicennia

Avicennia

Searching for oysters in young

Avicennia area

Mangroves and habitation

Vietnam, Pho Loc island

Observation station

Rizophora

Avicennia

Pneumatophores

mangrove research in the field

decreasing mangrove forests

artificial protection

Storm damage to mangroves

Revetment, toe and mangroves

wave transmission through

mangroves (100 m)

Load reduction over a dam

wave transmission dams

water exchange possibilities

Detached “breakwater”

•Grass is a flexible, renewable slope protection

•Grass can withstand quite some load

•Environmentalists do not like “monocultures”

•Fortunately from an engineering point of view, variation is also better

•Hydraulic engineers like roots, farmers like leaves

A typical grass dike

grass and clay layer

Texture formation

in the clay body

Texture formation = structuurvorming Textured =

gestructureerd

Cattle and light fertilising

No cattle, removal of grass Fertilising, and no removal of grass Cattle, fertilizer and herbicides

exposed turf

grass tests in the large

wave flume

load and strength of grass under

wave attack

experimental set up

results of erosion tests

Fertilised + cattle

Non-fertilised after 25 yrs

Non-fertilised

erosion speed as function of wave height

Erosion speed of a grass turf

Quality c E

good 0.5 - 1.5 moderate 1.5 - 2.5 bad 2.5 - 3.5

permissible duration of wave load

and grass quality

Vetiver hedge (Vetiveria zizanioides)

Worldwide distribution of Vetiver

Vetiver nursery

Agricultural University,

Ho Chi Minh ciyt, Viernam

Vetiver seedlings ready

for transport

Vetiver seedling

Vetiver as shoreline protection

Vetiver as run-up reductor

End of Chapter 10