Effects of Waves, Currents and Tides on Coastline

Effects of Waves, Currents and Tides on Coastline

The processes of waves, tides, and currents formation occur naturally in the ocean and are influenced by several factors. First, tides can be defined as the rise and fall of ocean water and they occur as a result of the gravitational attraction of the sun and the moon. The change in the position of the celestial body has a direct effect on the surfaces’ heights. Similarly, different locations experience varying levels of tides due to the shape of coastline (Han, Jekeli, & Shum, 2011). In some parts of the ocean, the length of the tide may be few centimeters while in other parts it may reach over ten meters.

Second, Waves are caused by the wind that carry a lot of energy and when they come into contact with the ocean surface, they create friction between the water and air molecules. The wind energy is then transferred to the water forming waves in oceans and ripples in lakes. Once the waves leave they become organized into groups depending on their speed. Moreover, as they travel towards the coastline, they change shape and direction under the influence of the underlying seabed (Davidson-Arnott, 2010). A stronger wind will always result to larger waves (Han, Jekeli & Shum, 2011). Lastly, ocean currents are connected streams of water that circulate through the ocean. They are mainly caused by the wind, earthquakes, gravity and the process of thermohaline circulation.

My favorite coastline is Big Sur, and it is located in California along the Santa Lucia Mountains on the central coast. The coastal landscape is broadly divided into two categories that include the rocky cliff and sandy beaches. Besides, Big Sur has the former features making the coastline have a rugged stretch. Due to the rising land in the area, the coast of Big Sur is dominated by cliffs and steep faces of rocks. Also, the coastline has been subjected to constant erosion from the strong waves that continuously blow. As the waves move and break against the cliff, some features are formed. However, their formation depends on the hardness of the rock. The waves may cause what is known as a wave-cut notch at the base of the cliff. When this notch increase in size, the rocks on the cliff face above lose support. They will then fall into the water as fragments and with time, they will be eroded by the strong ocean waves blowing over them. The process of forming a wave-cut notch will continue over time by slowly retreating inland. As this process continues, a steeper beach profile is created.

Waves are the cause of sand deposition in some parts of the Big Sur since they move sand each time they break along the beach. Large waves tend to remove sand from the beach while small waves tend to deposit sand on the beach. The size of the sand particles that are deposited on the beach is determined by the energy of the waves that picks the sand up and determine how far they will be deposited (Davidson-Arnott, 2010). On the same note, a steady stream of small waves may deposit large sand on the beach hence increasing the width of the coastline.

The ocean currents in Big Sur coastline is caused by the climatic condition of the region and the nature of the coastline. The prevailing winds and the rugged nature of the landmass causes the ocean water to move in a certain direction. The ocean currents in Big Sur have the following effects on the coastal region. When winds blow over a warm ocean current, they become warm. In the process, they also pick up moisture since the wind that is warm is capable of retaining more moisture. The warm temperatures accompanied by the wind movement evaporates the water as the moist air blows over the land. Due to the reduction in temperature, the moist air cools and fall as rain. Big Sur coastline moderate heat which could have otherwise been hotter and it is because of the winds blowing over the cold and dry ocean current. The ocean currents in California, which is cold, and flows along the coast of USA make the region much cooler than the other places in the west of the same altitude. Such winds have little or no moisture which in result bring little or no rainfall over the coastal region of Big Sur (Han, Jekeli & Shum, 2011).

The occurrence of tides in Big Sur have impacted the region in the following ways. First, the continuous change in the levels of water has led to the exposure of the different parts of the coastline to wave energy. In a situation when we have large tidal range, the water may rise and fall as far as 10 meters. Geologically, the tides expose the intertidal zones to erosion and deposition (Davidson-Arnott, 2010). Second, tidal currents are stronger near the coast of Big Sur, and they play a significant role in local circulation. They have the capability of eroding and transporting sediments.

On the same note, the variations in the heights of the tides are dependent on the month because the moon is not always at the same distance from the earth. As the orbit of the moon brings it closer to the earth, its gravitational force increases by 50%. Such stronger forces will then lead to high tides, and the opposite happens when the moon is further away from the earth (Davidson-Arnott, 2010). During high tides, sand, ocean sediments and shells are brought to the beach. Also, the amount of water in inlets found in Big Sur coastline change with the tides.

The rise and fall of tides along an open coast like Big Sur have indirectly affected the transportation of the sediments. The shape of Big Sur coastline has changed due to the deposited sand and sediments. As the tides come in and then retreats along a beach or a rocky coast, it causes the shoreline to change accordingly. The zones where waves and long shore currents move are shaped by the movements of tides. Tidal range in combination with the topography of the area is critical because the higher the tidal range, the more impact it has on the coastline (Davidson-Arnott, 2010). On the other hand, in periods when Big Sur coastline experiences strong lunar tidal cycles, the tides decrease both the ocean’s surface temperature and air pressure. This, in turn, affects the variability of rainfall in the region.



Davidson-Arnott, R. (2010). Introduction to coastal processes and geomorphology. Cambridge: Cambridge University Press.

Han, S. C., Jekeli, C., & Shum, C. K. (2011). Time‐variable aliasing effects of ocean tides, atmosphere, and continental water mass on monthly mean GRACE gravity field. Journal of Geophysical Research: Solid Earth, 109(B4).

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