COASTAL ENGINEERING

• Is a division of civil engineering responsible for the organization, conception, development, and preservation of works along shorelines.

  Coastal Engineering
• Costal Engineering - involves harbor works, navigational channel improvements, shore protection, flood damage reduction, land reclamation, and environmental preservation and restoration.
• What is the total land area of Coastal Development in Philippines?

  115,739 sq.m.
• Coastal engineering is a division of civil engineering responsible for the organization, conception, development, and preservation of works along shorelines
• It involves harbor works, navigational channel improvements, shore protection, flood damage reduction, land reclamation, and environmental preservation and restoration
• In the Philippines, 70% of more than 1,500 municipalities are located in the coastal area
• Coastal fishing activities in the Philippines account for between 40% and 60% of the total fish catch
• Major ports in the Philippines include Port of Manila, Port of Cebu, International Port of Batangas, Port of Subic, Port of Cagayan de Oro, Port of Davao, Port of Iloilo, Port of General Santos, Port of Zamboanga, and Port of Lucena
• The Philippines has five Port District Offices (PDO) and 19 Port Management Offices (PMO) under the PDOs
• Coastal erosion is the process by which local sea level rise, strong wave action, and coastal flooding wear down or carry away rocks, soils, and/or sands along the coast
• Coastal erosion becomes hazardous when people build structures in the coastal zone that do not complement its natural evolution and processes
• Siltation of coastal waters is increased by soil erosion arising from agricultural practices, deforestation, destruction of mangroves and seagrass beds, and marine dredging
• Coral reef destruction is caused by illegal fishing techniques, pollution, careless tourism, earthquakes, and hurricanes
• Sea level rise is caused by the added water from melting ice sheets and glaciers, and the expansion of seawater as it warms due to global warming
• A wave is any disturbance created when energy moves through an object or substance
• The height of a wave depends on the speed of the wind causing the disturbance on the surface of water
• Waves propagate through a medium, with the source of the wave generating external forces
• Characteristics of a wave include crest, trough, height, amplitude, wavelength, frequency, and period
• Tides are the result of a combination of forces acting on individual water particles, including gravitational attraction of the earth, centrifugal force, gravitational attraction of the moon, and gravitational attraction of the sun
• Equilibrium tides conceive a hypothetical global ocean in static equilibrium with tide-producing forces
• The moon's gravitational attraction and the centrifugal force generated by the rotation of the Earth-Moon system result in two bulges of high water, causing two high water levels and two low water levels per day
• During spring tides, the solar and lunar double bulges add to each other to produce the largest tidal ranges
• Daily inequality in tides occurs when the two high tides each day are not the same height, noticeable when the moon and sun are farthest north or south of the equator
• Tide analysis involves separating a measured tide into its constituents using harmonic summation
• Tidal currents are periodical horizontal movements of the sea due to tide-generating forces, affecting factors like the shape of the bay, river flow, channel shape, and friction
• Water levels can be raised and lowered using substantial currents that propagate at the shallow water long wave velocity due to their long wavelengths
• Tidal computation involves complex computational models to calculate water levels, flows, salinities, and densities in estuaries
• Storm surge is an increase in water level resulting from shear stress by onshore wind over the water surface
• Storm surge occurs simultaneously with major wave action and is the cause of most disastrous flooding and coastal damage worldwide
• The Philippines is highly prone to storm surges due to its location near the equator in the Pacific Region and the extensive length of its coastline
• Examples of storm surges in the Philippines:

  1. Tacloban City, Leyte (2013) - Super Typhoon Haiyan (Yolanda) caused catastrophic devastation with a devastating storm surge.

  2. Bicol Region (2018) - Typhoon Usagi led to storm surges affecting areas like Sorsogon and Albay.

  3. Eastern Visayas (2020) - Typhoon Vamco (Ulysses) brought severe flooding and storm surges to parts of the Eastern Visayas region
• Difference between tsunami and storm surge:

  • Tsunami can be seismic or non-seismic, caused by phenomena like earthquakes or meteorites.
  • Storm surge is associated with tropical or extra-tropical cyclones where heavy winds trigger an abnormal rise in water levels
• During a storm surge, the water level at a downwind shore rises until gravity counteracts the shear stress from the wind
• Computation of storm surge:

  • Calculated using depth-averaged two-dimensional equations of motion and continuity
  • Wind-generated shear stress is the main driving force
• Barometric surge:

  • Refers to a sudden and significant change in barometric pressure
  • Accompanies storm surge due to large pressure fluctuations
• Seiche:

  • Refers to a standing wave oscillation in an enclosed body of water
  • Occurs due to factors like wind, changes in atmospheric pressure, or seismic activity
• Seasonal fluctuations:

  • Do not occur along the open ocean but happen in lakes and upper estuaries
  • Normally taken into account in design
• Long-term water level changes:

  • Occur over consecutive years due to wet and cold or warm and dry periods
  • Response to long-term climatic changes is a cause for concern
• Eustatic (sea) level change:

  • Global change in ocean water levels due to melting or freezing of polar ice caps and thermal expansion
  • Present average rate of rise is estimated at 1 to 1.5 mm/yr
• Isostatic (land) rebound & subsidence:

  • Result of the earth's crust adjusting to the release of pressure from the last glaciation