Final answer:
Groynes on the Northern beach can lead to increased sand deposition, protecting property and enhancing the beach. Yet, they also cause downstream erosion and habitat disruption, potentially harming marine life and local economies.
Step-by-step explanation:
What have groynes done to the Northern Part of the beach? Groynes, as coastal protection structures, are designed to control sand movement and prevent erosion of beaches by disrupting the longshore drift. When implemented on the Northern part of a beach, they can contribute to increased sand accumulation on the updrift side, which may improve the beach area for human use and protect properties located there. However, these structures can also have negative impacts.
They may cause downstream erosion on the downdrift side due to the restriction of the natural flow of sand, leading to beach narrowing and potential habitat loss. Furthermore, groynes can contribute to the alteration of local currents and sedimentation patterns, potentially damaging local ecosystems, such as seaweed beds and reefs, a factor that has profound effects on marine biodiversity. The interruptions in sediment transport can impact marine life, with consequences for local fisheries and tourism, which are critical components of many coastal economies.