Coastal environment

Coastal environment

1. Coastal Environment Topic 2 A-level Physical Geography

2. Introduction Coastal environments are the interface between 3 natural systems: Atmosphere, Ocean, Land Coastal zone refers to an area influenced by proximity to the coast

3. Introduction Offshore zone refers to the portion of the profile where there is no significant transport of sediment by wave action Littoral zone refers to the portion of the coastal profile where sediment can be transported Shore/ beach: Area of the coast sub aerially exposed some of the time but remains subjected to wave action

4. Introduction Foreshore : Subjected to wave action periodically during non-storm conditions Backshore : Subjected to wave actions during storms Swash zone: Zone of wave run-up on the beach and return of water in the form of backwash Intertidal zone: Zone between high and low water (tide) Shoreline: The intercept of the mean water level along the beach but it is often used loosely as swash limit or landward edge of the backshore

5. Content Coastal Processes Characteristics and formation of coastal landforms Coral Reefs Sustainable Management of Coasts

6. Factors influencing Coasts Lithology/ rock types Geological Structures Processes Sea-level changes Human Impacts Ecosystem types

7. Lithology Hard rocks Granite, Basalt Rugged landscape Soft rocks Sands/ gravels Flatter landscape

8. Geological Structure Concordant Coast Discordant Coast

9. Processes Tides/ diurnal fluctuation of sea level Wave action: Erosion/ Deposition Currents (Longshore/ Rip) Winds

10. Sea-level Change Interacts with points/ rates of erosion and deposition Advancing coast (deposition/ relative change in sea level) Retreating coast (erosions/ relative change in sea level)

11. Human Impacts Modification by humans To protect settlements near the coast Mitigate problems of erosion Primary industries/ agriculture/ aquaculture Industries/ Tourism Mining Impacts of externality

12. Ecosystem Types Influences the rate of weathering Some can act as wave barriers Coral Reefs Mangroves Saltmarshes Sand Dunes Rocky Shores

13. Coastal Zones All areas from the deep ocean to point around 60 km inland Inland areas can affect coastal areas by controlling sediment supply and on-land pollution sources Inland areas can also be affected by coastal processes e.g. sea breeze can affect land temperature

14. Upper beach/ Backshore Limit of high water to dunes/ inland limit (60 km) Only affected by waves during storms/ unusual high tides Well-sorted/ well rounded sediments Coarse and medium sands

15. Foreshore Region between the high and low water marks Sediments may include: Soft, mobile/ semi mobile sediments (sand, mud, shingle) A different case for rocky shores

16. Coastal Processes

17. Wave A result of the friction between the wind and the sea Forward surges of energy The water particles are not moving They move in circular orbit Wave orbit is the shape of the wave: Circular or elliptical Diameter or orbit decreases with depth

18. Wave Wave Crest: Highest point of a wave Wave base: Point at the bottom of a wave where there is no movement related to wind energy Wave length: Distance between two successive crests/ troughs

19. Wave

20. Wave Characters Waves are characterized by their height, length and period Height: distance between trough and crest Length: distance between two wave crests Period: the time for 2 consecutive wave crests to pass a given point Amplitude: distance from wave base to crest

21. Wave Energy Carriers of energy Imparted to them by wind Energy per unit surface area of waves is proportional to the wave height square Speed = wave length/ wave period

22. Breaking Waves Energy for movement of waves come from the open ocean Differences in atmospheric pressure creates a gradient down which the air flows Flow of air is known as wind The friction between the wind and the surface of the ocean pushes water in certain directions

23. Breaking Waves The energy is propagated in the form of swell waves Wave energy oscillates , moving water particle in an elliptical or circular motion, and then returning it back to its position As the waves reach the shore, they become breakers

24. Breaking Waves The consistency of wave motion is disrupted as it approaches the changing topography of the shoreline

25. Shoaling As wave approaches shoreline, its base grazes the ocean floor The friction causes the wave base to slow down However, movement of water particles at the wave crest continues This causes multiple waves to combine Thus increasing the height and amplitude of the waves This is shoaling

26. Shoaling Occurs as waves enter shallow water Speed/ length decrease Wave height increases Crest becomes too steep – unstable Curls forward and breaks on the shore

27. Breakers Breaking waves are waves whose amplitudes reach critical levels at which some processes occur to transform wave energy into turbulent kinetic energy 3 types: Spilling breakers Plunging breakers Surging breakers

28. Spilling Breakers Ocean floor has gradual slope Wave steepens Crest becomes unstable Turbulent whitewater spilling down wave face – slowly dissipating wave energy Gentle wave is created Takes longer time to break

29. Plunging Breakers Steeper ocean floors – sudden changes in depth Crest becomes much steeper Curls over and drops onto trough Breaks with more energy

30. Surging Breakers Long period gentle wave with steep beach profile Rapid movement of wave base up sop and wave crest disappearing The wave slides and swells up the shore

31. Constructive Waves Destructive Waves Low Gradient High gradient Low Wave height High wave height Long wave length Short wavelength Wave frequency 6 – 8 / minute Wave frequency 10 – 14 / minute Swash > Backwash Backwash > Swash Spilling breakers Plunging/ Surging breakers Sheltered Coasts Exposed Coasts

32. Tide/ Tidal Cycle Regular movements of the sea surface caused by gravitational pull of the Moon and the Sun on the ocean Gravitational pull of the moon causes water to bulge at the area of the earth surface facing the moon The opposite side of the earth surface is similarly affected by the centrifugal force

33. Tidal Cycle

34. Tidal Cycle At full moon and new moon (syzygy – when earth moon and sun alig n ), the gravitational pull is maximized by the pull of the sun These times between new moon and first quarter moon and full moon and third quarter moon are known as Spring tides – maximum height of tide The other times, there is only moon’s pull and the tide is lower – Neap tide

35. Tides and shorelines Tides are greatest at bay and funnel shaped coastline – less area thus water pile up more : Tidal bores Northern hemisphere, water deflected to the right Every decrease in 10 millibars = 10 cm rises

36. Tidal Range Difference between high and low tide Highly variable 15 m in bay of Fundy Canada Varies with distance from amphidromic points (areas where there is no tidal range)/ shape of coasts

37. Tidal Range Microtidal < 2 m Mesotidal 2 > x > 4 m Macrotidal > 4 m

38. Impacts of Tides Vertical range of erosion/ deposition Weathering Biological activities Velocity of tidal flows can affect erosional/ scouring rate Can cause rip currents

39. Storm Surges Changes in sea level caused by intense low pressure/ high wind speed During intense low pressure, pressure can drop by 100 mb – surges reaching up to 1 meter During cyclones/ storms, surges are common Can cause casualties in flooding Can inundate farmlands/ residential areas

40. Wave Refraction Bending of waves due to varying water depths Areas closer to shores are shallow Thus waves in those areas slow down So the waves seem to be slowing down to break parallel to the shore Waves will wrap around the island

41. Wave refraction Refraction can be incomplete, causing longshore drift A process of sediments transportation causing by the waves hitting the shore at an angle to the prevailing wind

42. Marine Erosion Waves can erode materials and sediments on shores Hydraulic action: waves hit against cliffs, air trapped in cracks/ joints/ bedding planes – placing them under pressure Wave retreats This creates explosive forces Known as cavitation

43. Marine Erosion Stresses reduce rock coherence Highly effective against well jointed/ bedded rocks: limestone, sandstone, granite, chalk Or poorly consolidated rocks: clays/ glacial deposits AKA wave pounding

44. Marine Erosion Abrasion: pebbles/ shingles hurled at surfaces Attrition: materials worn themselves down Solution: chemical erosion Calcareous rocks: waves may remove materials with acidic water Organic acids from organisms like barnacles/ limpets

45. Factors affecting rate of erosion Wave Energy Waves Wave Steepness – steep destructive waves have greater abrasive/ hydraulic power Wave should also break close to cliff base for highest energy Tides Tides can affect zones of erosion/ powerful tides have scouring effects Currents Longshore/ rip current erode materials Winds Onshore wind can erode beaches to form dunes Offshore winds erode dunes to nourish beach Longer fetch = greater wave energy

46. Factors affecting rate of erosion Material factors Sediment Supply Abrasion can only occur with continual supply However, oversupply can form effective protections Width of platform Platforms before cliffs can absorb wave energy, longer platforms = less wave energy Rock resistance Granite = highly resistant Unconsolidated volcanic ash = less Overlying rocks with different resistance promote differential erosion Rock structures/ dip Well jointed/ bedded/ faulted rocks susceptible to cavitation Horizontal/ vertical structures = steeper cliffs Strata dipping away from sea = stability = gentle slopes

47. Factors affecting rate of erosion Shore Geometry Offshore Topography Steep seabed = higher/ steeper waves Longshore bars cause offshore breaking = loses energy Orientation of coast Headlands affected by refraction: energy concentrated Degree of exposure influences rate of erosion Direction of Fetch Longer fetch – great potential for wave erosion

48. Sub-Aerial Processes Cliff face processes Salt weathering: Sodium/ magnesium compounds expand in cracks/ joints Freeze thaw weathering: Water freezes and thaws, the cycle of expanding and contracting weakens the rocks and allow deeper penetration Biological weathering: Molluscs, sponges, sea urchins Solution weathering: organic acids from organisms Slaking: Material disintegrated when exposed to water: hydration cycle Mass movements

49. Marine Transportation/ Deposition Sediment sources vary in beaches Beach deposits, Offshore marine deposits, river deposits, glacial deposits, materials from mass movement, wind-blown sediments/ artificial beach nourishment

50. Marine Transportation/ Deposition Beaches can be made of many materials Sandy beach, shingle beach, volcanic ash beach Sediments are transported in 4 forms Like in river transports

51. Marine Transportation/ Depositions Bedload: Traction (dragging of large materials) or saltation (discontinuous jumping) – pebbles/ shingles Suspended loads: Turbulent flows carry grains – silt, sand Wash loads: Clay/ dissolved materials in constant suspension

52. Sediment Cell Coastal sediment budget/ cell is the system of identification of sediments sources and sinks Quantifications of amounts/ rates of sediments erosion, transportation/ deposition within a defined area Helps engineers to project future shoreline changes

53. Characteristics and formation of coastal landforms

54. Erosional Landforms

55. Cliffs Waves erode the base of the cliffs This creates notches It also leaves overhangs The overhangs soon collapse

56. Notches/ Geos These can form at the bases of steep cliffs. U sually located in the intertidal range where wave energy is the strongest and most concentrated. Wave action cuts a small depression at the base of the cliff face. Water will continue to crash in the depression, widening the gap.

57. Caves Caves can form at cliff bases or headlands The erosion of seawater creates caves and caverns This landform may start as a small tunnel before widening to form large caves Develop from notches and geos

58. Arches If the sea caves are formed at the base of headlands, erosion may continue to the point where the caves reach the other side of the headlands T wo caves formed at either side of the headland will join to form arches.

59. Stacks Overhang of the arch soon collapses Leaving a tower-like landform disjointed from the mainland

60. Stumps Stacks may be further eroded at bases This leads to the stack falling over Leaving a stump

61. Rocky Shores An intertidal area of sea coasts where solid rocks predominate Biologically rich Consists of cliffs, platforms, pools, boulder fields Most features are erosional Controlled by actions of tides, wind, wave and insolation

62. Rocky Shores Variations in morphology due to: mineralogy, lithology, tectonic history, climate, wave actions, tidal ranges Rocky shores will consist of the platform and the cliffs

63. Platforms Can be horizontal with steep sea ward edge (Sub horizontal) Or gently sloping to the sea Sloping platforms: macro tidal range with dominant wave action Sub horizontal platform: micro tidal range

64. Platforms Resistance platforms can be enhanced by carbonate precipitation at limestone formations of silica/ iron elsewhere Platform erosion occurs as a result of waves and currents Chemical weathering plays an important role in the sub-aerial processes

65. Cliffs Profiles Dip of the bedding affect cliff profiles Vertical dip = sheer cliff face Seaward dip = shelving cliffs prone to landslide Model of cliff evolution will take in account the dynamic between wave action and sub aerial processes

66. Processes that impact rocky shores Mechanical wave erosion Weathering Bio-erosion Mass movements

67. Mechanical wave erosion Erosion Loose materials removed by wave Energetic wave condition Microtidal range Abrasion Wave -induced flow with mixture of sediments scour surfaces Soft rock for cliffs/ platforms Energetic waves Supply of sediments (thin layer) Microtidal range Hydraulic Action Wave-induce pressure, cavitation widens rock cracks/ joints Weak rocks with joints/ bedding planes Energetic wave conditions Microtidal range

68. Weathering Physical Frost action/ cycle of wet-dry Cool climate Sedimentary rocks Salt Volumetric growth of salt crystals widen cracks/ joints in rocks Sedimentary rocks Warm/ dry climate Chemical Carbonation Hydrolysis Oxidation Hydration Solution Sedimentary rocks of specific mineral compositions Warm/ wet climate Water layer leveling Physical, salt and chemical weathering combine in actions at edges of pools Sedimentary rocks Warm/ wet climate with high rate of evaporation

69. Bio-erosion Biochemical Chemical weathering caused by products of metabolism Limestone Tropical climate Biophysical Burrowing Grazing Digging Areas of fair biodiversity and species abundance

70. Mass Movement Rockfalls/ Toppling Rocks fall/ roll straight down cliff faces Well jointed rocks Undercutting by waves Slides Deep seated slope failures Deeply weathered rocks Some moistures Serious undercutting/ loading Flows Flow of loose materials Unconsolidated materials or regolith Moisture Undercutting or loading

71. Composite Cliffs Cliffs that are composed of more than one rock types Profiles of such cliffs may be influenced by differential erosion Relative strength and permeability of such rocks

72. Uniform cliffs Cliffs with uniform rock types Cliff recession will be steady and uniform Weaker rocks = faster retreats Glacial tills = fast retreats, vice versa for granite

73. Cliff Profiles In composite cliffs, the interactions between sub aerial processes and wave actions are essential If weaker rocks overly stronger rocks, the cliff will see higher erosion at the top of the cliffs On the other hand, undercutting will cause cliffs with underlying weak rocks to recede fast

74. Permeability If permeable rocks overly, the cliffs risk becoming prone to chemical weathering and becoming saturated Such cliffs will e at risk of mass movement

75. Strata Strata dipping in land is more stable than sea ward dipping strata

76. Bevelled Cliffs A cliff whose upper part has been trimmed to a relatively low angle Formed under three stages: Pre-glaciation Glaciation Post Glaciation

77. Pre glaciation Vertical cliff formed during the last interglacial warm period S ea level higher than it is today

78. Glaciation Glacial period – water stored as ice onland sea level dropped solifluction / freeze thaw trimmed upper part of the cliffs Forms bevelled edge materials accumulate at the bottom wave cut platform

79. Post-Glaciation Sea level rose again Renewed wave action erodes accumulated material Steepen cliff base Leaves upper part at low angle

80. Coastal Platform Many experts claimed that the sea level during post glacial time has not been consistent enough to erode many of the wave cut platforms around the world There is a theory that they are in fact ancient relict of the time when sea level was more consistent

81. Coastal Platform After isostatic recovery, some waves/ tidal actions still have minor impacts Sub aerial processes within and above the inter tidal ranges maintain the platforms

82. Depositional Features

83. Beaches The accumulation of materials deposited between the High Water Mark (HWM) and Low Water Mark (LWM) Typical beach has 3 zones: Offshore, foreshore, backshore

84. Formation of Beaches Strengths/ characteristics of waves determine the processes of deposition When waves bring sediments to shore, those sediments can be deposited or held in suspension

85. Sources of the sediments Longshore currents Headlands/ other landforms Corals/ other biological organisms

86. Wave Types For constructive waves: There are sufficient periods between crests so that materials can settle For destructive waves: periods between crests too short – materials not allowed to settle and taken away by drifts in suspension Stronger backwash also removes materials Constructive waves increase steepness Destructive waves make beaches more gentle

87. Role of sediments Eroded particles increase viscosity, volume, density and abrasive quality of the water So turbid water also increase erosive power of wave

88. Role of sediments Beaches with larger particles allows greater percolation, reducing power of backwash and maintaining steepness Beaches with compact sand allow more defenses against wind and wave erosion

89. Deposit forms Littoral deposits will drop at foreshore zones where wave energy remains higher High turbidity in coastal areas increase rate of attrition and allows for formation of neritic deposits Neritic deposits are found offshore where energy is only consistent above wave bases

90. Berm Fine, dry deposits found above the HWM Can be deposition from storm waves or relicts from when sea level was higher It is usually sloping May have dunes

91. Shingle Ridges Ridges of coarse materials pushed up by spring tides or storm waves Far above the HWM May form storm beaches

92. Cusps Can be caused by scalloped edges of swash Actions of two wave fronts from opposite directions Usually has arches of coarse materials

93. Cusps Cusps are self perpetuating Swash can be broken, concentrating energy on the cusps but allowing deposition of fine sediments at the embayment Cusps: Develop in high tidal range – waves approach shore at right angle

94. Fulls Ridges of sediments pushed up by constructive waves Run parallel to water line Varies with height of tides

95. Swales Troughs/ depressions Separate fulls

96. Bayhead Beach Sediments are deposited in bay area due to low energy Sediments can come from nearby headlands Beaches will be more stable due to lower wave action More of a closed system with less waves/ currents

97. Offshore Bars Long narrow ridge of materials lying parallel to the coasts Friction of low lying shoreline may cause wave to break early Materials are deposited Once initiated the ridge self perpetuates by causing waves to break more Offshore bars may grow and form lagoons

98. Swash-aligned coasts Oriented parallel to crests of prevailing waves Closed system No longshore drift No littoral drift

99. Drift-aligned coasts Oriented obliquely to the crest of the prevailing waves Controlled by longshore drift processes May lead to formations of spits, bars, tombolos

100. Localized Depositional Features Spit Creeks Bars Tombolo Cuspate forelands Offshore Bars Barrier Beaches Coastal Dunes Saltmarshes Mangroves

101. Conditions for depositional features Abundance of shingles and sands Irregular/ transverse coastline Vegetation Estuaries and main rivers

102. Spit Develop at indented coastlines with bays or estuaries Wave energy reduced in those areas Sands are deposited in the direction of longshore drifts Drift-aligned features Always joined at one end to mainland

103. Spit Refracting waves can give spits curved ends Recurved spits and recurved compound spits can be formed The area between spits and mainland may become saltmarshes

104. Creeks Sediments accumulate in the marshes Yet channels still exist These are called creeks

105. Bars A ridge of materials connecting two headlands Spits continuing to grow Onshore movements of materials can also form bars

106. Tombolo A ridge linking an island to the mainland Wave refractions form spits Grow to link up to the islands Wave refractions/ diffractions cause more deposition around the islands

107. Cuspate foreland Shingle ridges deposited in triangular shape May be a result of two sets of storm waves Can also be two spits joining

108. Barrier beaches Gently sloping/ low lying coasts Beaches/ ridges/ dunes form at the continental shelves Sea level rose and flood areas behind dunes A lagoon is formed Landward migration of barrier beaches begin

109. Coastal Dunes

110. Coastal Dunes Form when there is: Reliable supply of sand Strong onshore wind Large tidal range Vegetation to trap sand

111. Formation Onshore wind transports dry sands inland Vegetation slows down wind by friction Sands trapped by vegetation Forms small piles of sands

112. Formation Create more substantial wind breaks Cause more sand deposits High wind speed means dunes move inland, low wind speed means it remains static High supply of sand encourages formation of new dunes seaward

113. Sand dunes succession Salt spray from sea makes the dune’s ecology harsh Rotting seaweeds may provide nutrients Plants like marram grasses are adapted Young dunes: yellow dunes Grey dunes: high humus content

114. Sand Dunes Succession Coastal Sand dunes ( psammoseres ) – provides habitats for plants/ animals Closer to beach conditions are harsh due to lack of moisture/ nutrient and salt spray, wind abrasion and instability Toughest pioneer plants dominate it: marram As dunes move inland, more species appear due to increases in moisture, nutrient and humus content

115. Pioneer - Foredunes Sand crouch grass/ Lyme grass Tolerant to salt – waxy coating to retain water Roots bind sand producing more stable wind break Increase in sand deposits may soon bury the grasses

116. Yellow Dunes As Dunes move further back, the less tolerant but stronger marram grass takes over Marram grasses grow quickly and reach out from dunes Plants may grow in patches As wind speed reduces due to increase dune height, evapotranspiration reduces, increasing moisture

117. Grey Dune Plants cover the dunes in continuous pattern by now Humus layer from decaying vegetation help retain moisture Grey-green lichens colonize the dunes Shells provide supply of calcareous materials

118. Grey Dune Rain water leaches the nutrient making dunes acidic High quantity of quartz grain makes soil acidic

119. http://www.countrysideinfo.co.uk/successn/primary2. htm http://www.landforms.eu/Lothian/dune% 20succession.htm

120. Saltmarshes

121. Saltmarshes Occurs on low-energy shorelines Temperate, high latitudes Characteristic depends on sedimentation and subsidence rate Mud/ sand flats nourished by sediments from rivers/ streams Embankments, estuaries, barrier islands and spits Mangroves in tropics – subtropics (Salt tolerant trees instead of herbaceous plants)

122. Saltmarshes Low topography – low elevation – vast wide areas Popular to human population Deltaic marshes, estuarine marshes, back-barrier marshes, open coast marshes, embayment marshes, drowned valley marshes

123. Formation Tidal flats gain elevation from sediment accretion Rate/ duration of tidal flooding decreases Plants/ pioneer species colonize exposed surface Rivers and streams arrive – rate of discharge reduces due to low gradient – more sediments settle

124. Formation Filamentous blue-green algae fix silt/ clay Increase erosion resistance of sediments Assists sediment accretion Roots of plants retain sediments from rising tides Creating a sediment terrace Reduces depths of and duration of flooding Allowing other plant communities to grow

125. CORAL REEFS

126. Corals Corals are made up of organisms called polyps They have mineral (calcium) skeleton Symbiotic relationships with the Zooxanthellae – photosynthesize and pass food to the corals This supply of food allows corals to grow into massive reefs structures

127. Development of Coral Begin as polyps (like sea anemones) Attach themselves to hard surfaces in shallow seas (sufficient light) Polyps exude calcium carbonate  forms skeleton Zooxanthellae grow inside the polyps Zooxanthellae gets shelter Polyps get photosynthesis Symbiotic relationship

128. Rate of Growth Tropical reefs: 2.5 – 60 cm per year This can form huge structures The oldest/ largest living systems on earth

129. Conditions required Temperature Depth Light Salinity Sediment Wave action Exposure to the air

130. Types of Corals Fringing reefs Atoll reefs Barrier reefs Patch reefs

131. Fringing reefs Directly attached to a shore – borders it with intervening channels/ lagoons

132. Atoll reefs Circular/ continuous barrier reef extends around a lagoon without a central island

133. Barrier reefs Reef separated from mainland by deep channel/ lagoon

134. Theories of Origins Most of the Corals today are formed in the last glacial period Changes in sea levels during the Pleistocene is usually taken into account

135. Darwin-Dana - Subsidence Darwin observes that coral polyps flock together and grow upward Thus fringing reef grows from the bases of the volcanic islands, stopping at low tide level Land begins to subside due to tectonic forces However reefs continue to grow from the bases: bedrocks

136. Darwin-Dana Subsidence Reefs cannot survive in deep water – must grow Reef grows slow near coast but vigorous away from coast A lagoon is formed, and reef is now barrier Sediments accrete on the lagoon – keep land level constant Original island fully subside, leaving an atoll

137. Evidences for Data from deep drilling confirms that corals do grow on bed rock Bikini atolls in the Pacific Ocean Positive correlation age of corals and ocean depths Submerged valley east Indonesia Subsidence explains why corals are not buried by sediments – they accumulated at subsiding lagoon bottom

138. Evidences Against Some areas of reefs, such as Timor, show no evidence of subsidence Some lagoons with depths of 40 – 45 m but wide lagoon cannot be explained by subsidence Some barrier and fringing reefs grow close together – subsidence is a continuous process and should affect them at equal stages

139. Murray – Stand Still Theory Corals grow on submarine platform No change in sea level No subsidence or uplift Submarine platform is either eroded by wave action or had sediments deposited on Coming up to an optimum depths

140. Murray – Stand Still Theory Corals start growing Starting with fringing reefs Grow outward to form barrier reefs And then atoll

141. Evidence For

142. Evidence Against Submarine platforms are not common Optimum depth indicated in the theory is not universal Without subsidence, lagoon should’ve been filled with deposits Marine deposition and erosion at the given depth is contradictory

143. Daly Corals formed during the Pleistocene ice age Corals die after fall in sea leve l This leaves a wave cut platform made of the coral limestone Sea level rises again This allows reefs to grow from the wave cut platform

144. Daly At narrow platforms, fringing reefs grow Broader platforms see growth of barrier reefs Isolated island peaks saw growth of atoll

145. Value of Corals Coastal protection Biodiversity Economic Social

146. Coastal Protection Reefs have the effects of causing waves to break offshore This reduces the erosive effects of wave breaking on shore They also slow down storm waves and surges Protect mangroves and sea grasses from erosions

147. Biodiversity Rainforest of the sea Highly productive ecosystem Some animals feed on sea grass Some may use corals as shelters/ protection/ breeding Reef biomass and species diversity positively correlated

148. Economics Role in the fishery industry Role in the Tourism industry Source of raw materials Role in the conservation industry

149. Fishery industries Corals provide habitats for fishes and other marine animals They may be important to fishing industries and aquaculture Subsistence livelihood may be directly dependent on this

150. Tourism Industry Southeast Asian Reef System and Great Barrier Reef In the former, LEDCs depend on Coastal tourisms Aesthetic quality of reefs and biodiversity are important to the economy Since tourism makes up a large proportion of some country’s economic sector

151. Source of Raw Material Although most corals are being conserved, they can also be mined for limestone High biodiversity means possibilities of researches For medicines, genetic alleles etc .

152. Social Importance Many atolls – Timor, Maldives, Philippines, Australia are home to indigenous population In Maldives, sea level changes and erosion threaten many atolls Tsunamis can destroy vast areas of reefs

153. Cultural Importance Parts of the livelihood of indigenous population Many hunt and fish at corals The area has formed a part of their indigenous cultures

154. Threats to coral reefs Changes in sea temperature and bleaching Pollution and Sedimentation Fisheries and transports Invasive Species Eutrophication and Red Tide Tourism Overfishing

155. Sea temperature Global warming cause rises in sea temperature El Nino such as the one in 2016 can cause changes in temperature This is beyond Coral’s optimum Relationship between corals and Zooxanthellae broke Corals lose their white colors – bleaching Makes them more susceptible to diseases

156. Ocean Acidification CO 2 released into the atmosphere Combines with water to form Carbonic acid Acidic water can dissolve the calcium carbonate skeleton

157. Pollution and Sedimentation Water pollution encourages invasive species Makes water toxic and reduce biodiversity Reduces nutrients level Oil spill can block sunlight and prevent photosynthesis Releases of nutrients and fertilizers can lead to overgrow of algae

158. Pollution and Sedimentation This leads to eutrophication and red tide These organisms can ‘steal’ reefs’ nutrients Sedimentation from sea floor dredging, sand mining or coastal construction can make water murky Blocks sunlight for corals

159. Tourism Tourism encourages boats which may release oil Careless tourists may stunt coral growths by touching them In some cases bring home as souvenirs

160. Invasive Species Crown-of-Thorn Starfish May thrive in polluted water Eat corals Steal nutrients

161. Overfishing Reduce biodiversity Bombs to kill fishes can damage reefs

162. Coral bleaching When higher water temperature leads to severing of symbiotic relationship between Zooxanthellae and polyps, thus corals lose their colors, leaving white skeletons

163. 1998 bleaching 1998, coral bleaching reported all over the world: Pacific, Indian, Red, Mediterranean, Caribbean Indian corals most severely impacted Affected up to 50 m at depth The first globalized event Coincident with high sea temperature Unclear what caused rise (could be E l Niño but link unclear for Indian ocean) Global warming mentioned However, noted that other factors weakened reefs

164. 2004 Global assessment

165. Initiative in Climate Change and Coral Reefs 2010

166. 2011 Assessment

167. Climate change, coral and people

168. Evidence of climate-change damage to coral reefs

169. Management strategies to protect coral reefs

170. SUSTAINABLE MANAGEMENT OF COASTS

171. Management Defense against flooding, erosion and sea water encroachment Large number of population occupy coastal zones – need protections Rich I resources and economically significant

172. Shoreline Management Plans Large scale assessment of risks associated with coastal processes and helps to reduce these ricks to people and the developed historic and natural environment

173. Coastal defense Engineering methods to defend against erosions May be hard engineering or soft engineering

174. Human Activities and Coastal Zones Problems

175. Urbanization and Transport Can release sediments by dredging Disrupt sediment cells Urbanization means mining for sands Loading of nearby cliffs Increase in domestic pollution See Case Studies for more

176. Agriculture Using of coastal land areas e.g. Saltmarshes/ Mangroves for aquaculture Releases of fertilizers Eutrophication/ redtides

177. Tourism and Recreation Can damage coral reefs Increase domestic pollution Transportation need

178. Fisheries/ Aquacultures Aquaculture: Use land area Boats release oil Trawls/ nets damage reef systems

179. Industry Release of pollutants Chemicals and toxic materials

180. Hard-Engineering

181. Cliff-base management Defense of waves

182. Seawalls Wall used to defend against wave action Static feature going against the natural dynamic Used in high energy coastline Physically stop erosive actions of waves The fact that it goes against natural dynamics mean erosional problems increase elsewhere Sea level rises can render sea walls useless

183. Seawalls They are expensive to maintain They are not vetted for extreme storm events Calculation of wave strengths do no take in account outliers Unappealing to tourists

184. Revetments Sloping structures placed on cliffs to absorb energy of incoming waves Defend against crashing waves Low Cost Wooden revetments were used, now replace by concretes Not effective in storms Regular maintenance required Make beaches inaccessible Unappealing to tourists

185. Gabions Cage or box filled with rocks and concretes They have strong structures Can conform to subsidence Dissipate energy of flowing water/ resist washing away

186. Gabions Low cost – easily constructed Flexible Unappealing to tourists Labor intensive

187. Groynes Low wall built out in the sea to check erosion and drifting Effective in reducing longshore But a direct intervention in the sediment cell transport

188. Rock armour Like seawall made of rocks Take a lot of budget to construct Labor intensive Beach is allowed Absorb energy of waves effciently

189. Offshore breakwaters Large stone structures that intercept waves Causing them to break before reaching shores Can lead to accretion of sediments offshore

190. Rock Strong Points Like groynes rocks dumped to create artificial headlands – reduce longshore drifts Cheap to build Easily repaired Disrupt downdrift

191. Cliff-face strategies Cliff drainage: Reduce possibilities of slope becoming saturated Increases sheer strengths Cliff grading: Reducing possibilities of failures by angle

192. Soft-Engineering

193. Offshore Reefs Coral reefs act as natural breakwater Slows down wave and make them break offshore Reduces coastal erosion But natural and may not directly disrupt system

194. Beach Nourishment Using sand to fill up beaches May be expensive due to the need to transport and purchase sand Does not disrupt natural system Disrupt natural system Short term solution as sand will be eroded still

195. Managed Retreats Solves the problem in reducing human costs However repaid with economic costs Cannot fully apply with the lower economic classes who cannot afford land inshore Take away livelihoods of fishermen

196. Acceptance Letting nature takes its course Adapting to the situation Political unappealing May induce migration to other areas Does not solve the problem

197. Red -lining Planning permissions for certain areas closer to coasts not allowed This is not full use of lands – politically and economically unsound However conservation-wise, highly effective Very cost effective