chapter 1 coastal &marine environment introduction

Coastal & MarineEnvironment

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Coastal & Marine EnvironmentIntroduction

Part 2 - Problems

Mazen AbualtayefAssistant Prof., IUG, Palestine


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Beach Profile DefinitionBeach Profile Definition

Source: ENVIRONMENTAL ENGINEERING FOR COASTAL SHORE PROTECTION, U.S. Army Corps of Engineers


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Coastal LandscapesCoastal Landscapes

Salt marshTidal flat

Estuary

River

النھرمصب

Salt marsh المستنقعات المالحةTidal flat مد والجزرال مسطح


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Coastal LandscapesCoastal Landscapes


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A "coastal ecosystem" A "coastal ecosystem" includes:includes:

• Estuaries and coastal waters and lands located at the lower end of drainage basins.

• Where stream and river systems meet the sea and are mixed by tides.

• All these water and land forms interact as integrated ecological units.


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1Chapter • Coastal wetlands are commonly

called: Lagoons, Salt marshes or Tidelands.

• Coastal wetlands were among the first places to be converted and developed for human activities.

Coastal WetlandsCoastal Wetlands


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The most common types of The most common types of coastal problems are: coastal problems are:

1.1. Erosion Erosion 2.Flooding 3.Salt intrusion 4.4. Pollution Pollution 5.Habitat degradation 6.Loss of biodiversity


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Coastal ErosionCoastal Erosion increases the loss of sediments. Some of the process that affect the coastal areas are:

1. Subsidence, the sinking of the sediments, reduces the coastal sediment.

2. Currents, can increase or reduce the coastal sediment load.

3. Riverine sediment flow, determines the amount of sediment available in the coastal areas.

4. Seasonal changes in sea level, changes the coastal sediment budget.

5. Seasonal storms, increase the offshore transport of coastal sediments.

Subsidence: رسوب


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Riverine sediment flowRiverine sediment flow


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1. Construction of dams reduces river sediment inflows.

2. Extraction of sediments from rivers alters the sediment inflows.

3. Extraction of fossil fuelsExtraction of fossil fuels and water and water causes subsidence.causes subsidence.

Fossil fuel: الوقود الأحفوري


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Rosetta Promontory

Mediterranean Sea

Nile River

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1996

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Aswan Dam

Construction of dams reduces river sediment inflows

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Extraction of sediments from rivers


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Extraction of fossil fuels


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ConsequencesConsequences

1. Loss of natural habitats and biodiversity.

2. Loss of beach areas and their recreational value.

3. Potential loss of infrastructure and buildings.

4. Reduction of natural protection against floods


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1Chapter Hurricane ImpactHurricane Impact

In assessing hurricane effects to natural resources, increases in: 1. Habitat diversity, 2. Productivity, 3. Fisheries, etc.

are regarded as positive and decreases as negative.


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1Chapter During hurricane Lili on The

French Bay some of the more branching forms of coral were damaged, especially Acroporapalmata.

Hurricane ImpactHurricane Impact

Sea fan

Acropoa palmata


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Damaged coral


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Storm wavesStorm waves caused extensive beach erosion in and around docks and results in theirs destruction.

On The French Bay all of the boards of the dock and part of the road were washed away.

Surge deposits from the storm deposited sand in the roadway and flooded areas.

Rushing water resulted in the deposition of a large apron of sand. High-energy waves rip up bedrock and toss it onshore.

Dock: حوض السفنPilings: دعائم


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1Chapter Storm wavesStorm waves


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1Chapter Storm wavesStorm waves


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Most beach erosion on the east coast of the United States can be correlated with human intervention with the natural migration pattern of barrier island inlets.

The channels migrate in the direction of the littoral transport under the influence of alongshore transport of sand, and onshore under the influence of sea level rise.

ErosionErosion

Littoral الساحلي :

Periodic dredging


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Humans attempt to stabilize the entrance position by:

1. building long jetties, 2. increase navigable depths by

dredging straight channels offshore.


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Beach restoration has become the method of choice for alleviating threats to property arising from erosion, this method is controversial due to economic and environmental concerns.

Restoration استعادة :alleviating: تخفیفcontroversial:جدل


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The Santa Barbara, California, breakwater is a classic case study of the effects of shoreline engineering.

To create a harbor for small boats, an L-shaped breakwater was completed at Santa Barbara in 1929.

Case Study I: Case Study I:

Santa BarbaraSanta Barbara harborharbor


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The original design left a gap in the west side, almost immediately sand began to pour through this opening to fill the harbor.

The breakwater that protected the boats from waves also protected the beach from the wave and current action that are essential to maintain the coastal sediment budget.

To halt the deposition within the harbor, the shoreward leg of the breakwater was completed in 1931.

Pour تصب :Halt:وقف

Deposition: ترسیب


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This literally "stop-gap" measure resulted in deposition along the seaward side of the breakwater which filled the area west of the shore leg in less than two years.

The University of California, Santa Barbara's athletic stadium is built on this "new" land.


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By 1934, sand had been deposited along the entire length of the seaward leg, had rounded the end of the breakwater, and was being deposited in the harbor again.

East of the harbor, the beaches were starved of sand.

Engineers estimated that about 98% of the sand transported by the alongshore current was being deposited in the harbor.

Starved: جوعان


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At Miramar Beach, 7km east of the harbor, erosion completely removed the 60m wide sandy beach by 1938, leaving behind only the rubble that was too large to be moved.


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10km farther east at Sandy land, the beach was cut back 75m during 1940.

Undermining and destroying the cottages built upon it.

Less severe erosion occurred as far along the coast as Rincon Point, about 33km east of the harbor.


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By constructing the Santa Barbara breakwater, several problems have been created:

1. Sand was being deposited in the harbor eroding other areas.

2. To everyone concerned, it was obvious that the harbor would soon become useless for anything but sun bathing and building sand castles unless something was done.

3. The lack of sufficient sand on the downdriftshoreline where valuable beaches and waterfront property had been destroyed.

4. The only solution was to move the sand from the harbor to the beaches, to artificially recreate the alongshore drift with dredges and pumps.

Drift: الانجراف


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Dredging began in 1938 and has taken place at two- to three-year intervals ever since.

The beaches have been partially replenished and the harbor is still in use.

The annual bill for dredging the harbor has varied from $350,000 to $1.7 million, depending on the amount of sand moved.

Replenished: امتلأت


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Santa Barbara is only one example of the type of problem that has occurred repeatedly with artificial harbors in California and elsewhere along coastal areas.

Dredging to prevent the closure of these harbors was costing the Federal government $7 to $8 million annually in the early 1980's.


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Case Study II: Case Study II: Erosion in FloridaErosion in Florida

In Florida, during December of 1996, strong winds and pounding surf carved up to 8m off several Dania, Hollywood and Hallandale beaches, reducing some to narrow strips at the base of towering seawalls.

The state estimates that 21 of the 24 miles of Broward beaches are eroded.

Carved: قسمت


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Up to 875,000 tons of sand, enough to fill 35,000 dump trucks, were ripped from the county's coastline during a five-day storm.

Dredging sand back to Broward's shoreline would cost an estimated $4.5 million.

The county has engage in shore protection and restoration since 1960’s.

County: مقاطعة


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Almost 22 miles of Palm Beach County's coastline had been judged critically eroded before the storm removed another 6 to 9m in some areas.

If the beaches are not replenished, fewer visitors may come to South Florida.


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chapter 1 coastal &marine environment introduction

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