Human activities, such as coastal development and climate change, have a significant impact on the dynamics of coastlines, leading to both advancement and retreat.

Coastal development, which encompasses the construction of buildings, roads, and other infrastructure, can profoundly affect coastal regions. These activities often involve clearing natural vegetation, which destabilizes the soil and increases erosion rates. As a result, the coastline can retreat as the ocean gradually erodes the exposed land. Additionally, the construction of sea walls and other coastal defenses can interfere with natural coastal processes, altering both the shape and position of the coastline.

On the other hand, climate change—largely driven by human activities such as burning fossil fuels and deforestation—represents another major factor influencing coastlines. Rising global temperatures contribute to sea level rise, primarily due to the melting of polar ice and the thermal expansion of seawater. This rise in sea level leads to increased coastal flooding and erosion, further causing coastlines to retreat. Moreover, climate change can trigger more frequent and severe storms, resulting in substantial damage to coastlines and exacerbating the retreat.

While it is less common, human activities can also lead to the advancement of coastlines. For example, the deposition of sediment and other materials can cause the coastline to extend seaward. This phenomenon may occur through activities like dredging, where sediment is extracted from the seabed and relocated, or through the construction of structures such as groynes, which trap sediment and promote its accumulation.

In conclusion, human activities significantly influence the advancement and retreat of coastlines. The predominant impacts are negative, resulting in increased coastal erosion, flooding, and alterations in the shape and position of coastlines. Nevertheless, certain human activities can also lead to coastline advancement, albeit less frequently. It is crucial to consider these impacts in the planning of coastal development and in the efforts to mitigate the effects of climate change.