1. The Coastal Ocean

2. Learning Objectives Students will be able to:
Describe various definitions for the coastal zone
Differentiate between pelagic and neritic processes
Classify estuaries in multiple ways and explain estuarine sedimentation processes
Articulate and describe beach processes
Describe the pros and cons to beach stabilization

3. Outline Definitions 3-D Ekman spiral Estuaries Estuarine Measurements
Habitat squeeze concept
Beaches and Shoreline Processes
Beach defense

4. Coastal waters Relatively shallow areas that adjoin continents
Heavily used for commerce, recreation, fisheries, and waste disposal
Military purposes as well

6. The Coast
The land and waters extending inland for 1 km from high water mark on the foreshore and extending to the 30 m contour line including all beds, sediments, waters and land subject to the ebb and flow of the tide.

7. Definitions A line extending 200 nm (370km) from the coast.
The 500 m isobath
A line a the foot of the continental slope
Territorial water- water adjacent to a coastal nation. Majority favor 3 miles, US wants 200.

8. EEZ The exclusive economic zone- 200 mile fishing and mineral rights.
Legal-UN Convention on the Law of the Sea- the seabed and subsoil that extends to the edge of the continental margin or a distance of 200 nm.

9. How does the Coastal Ocean Differ from the deep ocean?
Significant changes in Temperature, salinity and even pH. Very sensitive to environmental factors, like pollutants, contaminants, dissolved gases and nutrients.
May or may not exhibit constant proportions.
Bathymetry is a controlling factor in many physical processes.

10. How does the Coastal Ocean Differ from the deep ocean?
The pycnocline tends to follow the ______,
Instead of the ________. Why?
Friction can not be ignored this leads to 3-D Ekman system near the coast rather than the familiar 2-D one you know. Important implications for management issues.
The shoaling effect is prominent here.

11. 3-D Ekman We have all seen the 2-D Ekman spiral.
But what happens when the depth of the sea floor is less than the theoretical Ekman depth? Where does this happen?

12. Quasi geostrophic Flow
Pressure force
friction
coriolis

13. Overlap of bottom and surface Ekman layers DE DB
Flow at interior?
Flow at bottom? z -x
Overlap of bottom and surface Ekman layers
Importance of shelf break depth
Problems with Ekman theory – constant Az, constant wind, linear flow, steady state,
infinite ocean, no pressure gradients

14. Estuaries Estuaries are partially enclosed coastal bodies of water
Examples of estuaries include:
River mouths
Bays
Inlets
Gulfs
Sounds
Formed by a rise in sea level after the last Ice Age

15. Classifying estuaries by origin
Coastal plain
Fjord
Bar-built
Tectonic
Figure 11-3

16. Classifying estuaries by water mixing
Vertically mixed
Slightly stratified
Highly stratified
Salt wedge
Figure 11-5

24. Classification by Tides
Amplitude
Current
Head
Mouth
Head
Mouth
Head
Mouth
Hypersynchronous
Convergence>Friction
Synchronous
Convergence=Friction
Hyposynchronous
Convergence<Friction
The tidal range & currents increase towards the head of the estuary until the convergence diminishes & friction reduces the tide
The friction and convergence have equal and opposite effects on the tide
Friction is stronger and the tide diminishes along the estuary

25. AN interesting problem
We all know that coastal lagoons tend to silt in. This seems to be a problem, because this occurs against the concentration gradient.
The Dutch were the first to recognize this in the Wadden Zee.

26. The silting in of harbors and lagoons
So why does it happen?
It turns out there are a number of dynamical processes all conspiring to create this effect.
1- general estuarine circulation (salt wedge)
2 - the time velocity asymmetry of the shallow tidal wave.
3 - the settling lag effect

28. Beaches and Shoreline Processes

29. Landforms and terminology in coastal regions
Figure 10-1

30. Movement of sand on the beach
Movement perpendicular (↕) to shoreline
Caused by breaking waves
Light wave activity moves sand up the beach face toward the berm
Heavy wave activity moves sand down the beach face to the longshore bars
Produces seasonal changes in the beach

31. Light versus heavy wave activity
Light wave activity
Heavy wave activity
Berm/long-shore bar
Berm grows and longshore bars shrink
Longshore bars grow and berm shrinks
Wave energy
Low
High
Time span
Long
Short
Characteristics
Summertime beach: sandy, wide berm, steep beach face
Wintertime beach: rocky, thin berm, flattened beach face

32. Summertime and wintertime beach conditions
Summertime beach
Wintertime beach
Figure 10-2

33. Movement of sand on the beach
Movement parallel (↔) to shoreline
Caused by wave refraction (bending)
Each wave transports sand either upcoast or downcoast
Huge volumes of sand are moved within the surf zone
The beach resembles a “river of sand”

34. Longshore current and longshore drift
Longshore current = zigzag movement of water in the surf zone
Longshore drift = movement of sediment caused by longshore current
Figure 10-3b

35. Features of erosional shores
Headland
Wave-cut cliff
Sea cave
Sea arch
Sea stack
Marine terrace
Figure 10-4

36. Sea stack and sea arch, Oregon

37. Features of depositional shores
Spit
Bay barrier
Tombolo
Barrier island
Delta
Figure 10-7

38. Beach compartments in southern California
Beach compartments include:
Rivers
Beaches
Submarine canyons
Figure 10-12

39. Evidence of emerging and submerging shorelines
Emergent features:
Marine terraces
Stranded beach deposits
Submergent features:
Drowned beaches
Submerged dune topography
Drowned river valleys
Figure 10-13

40. Types of hard stabilization
Hard stabilization perpendicular to the coast within the surf zone:
Jetties—protect harbor entrances
Groins—designed to trap sand
Hard stabilization parallel to the coast:
Breakwaters—built beyond the surf zone
Seawalls—built to armor the coast

41. Jetties and Groins Jetties are always in pairs
Groins can be singular or many (groin field)
Both trap sand upstream and cause erosion downstream
Figure 10-21

42. Breakwater at Santa Barbara Harbor, California
Provides a boat anchorage
Causes deposition in harbor and erosion downstream
Sand must be dredged regularly
Figure 10-22

43. Seawalls and beaches Seawalls are built to reduce erosion on beaches
Seawalls can destroy recreational beaches
Seawalls are costly and eventually fail
Figure 10-24

44. Alternatives to hard stabilization
Restrict the building of structures too close to the shore
Eliminate programs that encourage construction in unsafe locations
Relocate structures as erosion threatens them
Relocation of the Cape Hatteras lighthouse, North Carolina
Figure 10C