Coastal Processes, Hazards, and Society

Module 2: Coastal Landscapes

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Module 2: Coastal Landscapes

Introduction

What is the coastline or shoreline? What is a coast or coastal zone?

For most of you, the terms coast or shore likely bring to mind visions of things such as vacations, waves, wind, sand, sailboats, coastal birds, and, perhaps, very bad cases of sunburn. Regardless of your first thoughts and whether you have ever been to a coast, if you were asked to define it, you would probably recognize that a coast is a location where the solid dry surface of Earth interfaces with the open-ocean environment. It is absolutely reasonable to think of the intersection of the water line with the firm ground as a coastline, but, in this entire course, we will be focusing on the intersection of the open marine/salty water/ocean/sea environment as the coastal zone. As you learned in Module 1, our global society is intrinsically linked to the coasts of the world and, for this reason, there is a wide range of interest in developing a sound scientific understanding of the form of coastal zones and the processes that cause them to change or evolve through time.

Throughout this course, you will hear or see the term coast or coastal zone. This is where an explicit definition becomes a bit more fuzzy and difficult to provide. Most scientists who conduct research within coastal zones would probably agree that the coastal zone, or coast, can be defined as a part of the land that is affected by processes of the open ocean, such as tides or salty ocean water. It includes the land above as well as below the water in these types of locations. On a global basis, coastal zones are highly varied and a single coastal zone may consist of numerous coastal sub-environments such as marshes and estuaries or may consist of a single type of environment such as a sandy beach at the base of some very high cliffs (the images below show some very iconic coastal zones). Consequently, they may be highly varied in their width, ranging between perhaps only a few hundred meters or as much as several hundred kilometers.

Regardless of the scale of the coastal zone, each coastal zone of the planet is characterized by a unique set of physical, chemical, and biological processes. Physical processes include things such as the daily movement of water and sand grains because of tides or waves. Chemical processes include the formation of small grains of the mineral calcium carbonate as it precipitates out of seawater. Biological processes include things such as the growth of plants in coastal marshes or the formation of small reefs in estuaries by organisms such as oysters. Collectively, all of the physical, chemical, and biological processes of a coastal zone interact to affect how a specific coastal zone looks, the ecosystems that are present there, the natural resources that are present, how it changes through time, and how we as humans interact with the coastal environments.

Finally, because of the diverse range of physical, chemical, and biological processes that exist in coastal zones, a solid scientific understanding of coastal zones requires a very holistic scientific approach with input from oceanographers, geologists, biologists, chemists, and engineers. In this unit, we will take a close look at how we classify coastal zones and the overall morphology and environments of coastal zones.

Classification of Coastal Zones

As humans, we love to be able to categorize things and create nice little compartments or classifications for the natural world around us. For example, think of how we have taken the animal kingdom and created a classification scheme that separates birds from mammals or invertebrates from reptiles on the basis of the differences between these organisms. Classification, regardless of what we are classifying, provides a way for us to organize things and then ultimately compare and contrast the differences between different parts of the natural world so that we can best understand how and why it developed.

During the last century, there have been numerous classification schemes proposed for coastal zones. Each one has had some good and bad ideas embedded in it, but one of the more recent and useful classification schemes of coastal zones relies upon understanding the concept of plate tectonics.