Factors affecting coastal processes and landforms — Eduqas A-Level Geography

Coastal processes and landforms are shaped by a combination of factors including wave energy, tidal range, geology, and human intervention. Understanding these factors is essential for predicting how coastlines evolve over time, which has significant implications for coastal management, habitat conservation, and human settlements. In the WJEC A-Level Geography syllabus, this topic forms part of the 'Coastal Landscapes' theme, where you explore the dynamic interactions between physical processes and human activity.

Key processes such as erosion, transportation, and deposition are driven by wave action, but their effectiveness depends on factors like fetch (the distance wind travels over water), wave type (constructive vs. destructive), and the resistance of the underlying rock. For example, hard rock cliffs (e.g., granite) erode slowly, producing steep, rugged landforms like headlands, while soft rock (e.g., clay) erodes rapidly, forming gentle slopes and wide bays. Tidal range also plays a crucial role: macro-tidal coasts (e.g., the Severn Estuary) experience strong tidal currents that redistribute sediment, whereas micro-tidal coasts (e.g., the Mediterranean) are dominated by wave action.

This topic is not just about memorising landform names; it requires you to analyse how different factors interact to produce distinctive coastal landscapes. For instance, the formation of a spit involves longshore drift (transportation), changes in wave direction, and the presence of a river estuary. By understanding these interactions, you can evaluate why certain coastlines are more vulnerable to erosion or why some areas experience rapid deposition. This knowledge is directly applicable to real-world issues like coastal erosion management and climate change adaptation.

• →Wave energy and type: Constructive waves (low energy, strong swash) build beaches, while destructive waves (high energy, strong backwash) erode them. Fetch and wind strength determine wave energy.
• →Geological structure: Lithology (rock type) and structure (joints, faults, bedding planes) influence erosion rates. Concordant and discordant coastlines produce different landform patterns (e.g., Dalmatian vs. Haff coastlines).
• →Tidal range and currents: Macro-tidal coasts (range >4m) have strong tidal currents that transport sediment, affecting estuary morphology and salt marsh development.
• →Sediment budget: The balance between sediment inputs (from rivers, cliff erosion) and outputs (longshore drift, offshore loss) determines whether a coastline is eroding, stable, or accreting.
• →Human intervention: Hard engineering (e.g., sea walls, groynes) alters sediment transport and can exacerbate erosion elsewhere, while soft engineering (e.g., beach nourishment) works with natural processes.

• Explanation of fetch, wave type, wave orientation, wave refraction, and wave reflection.
• Analysis of lithological factors including mineral composition, hardness, and solubility.
• Description of structural geology features such as bedding, dip, joints, folding, and faulting.
• Application of the systems framework to explain how these factors influence coastal processes and landforms.

• 💡Use specific terminology for structural geology (e.g., dip, joints, faulting) rather than generic descriptions.
• 💡Ensure you can explain how wave refraction concentrates energy on headlands.
• 💡Practice linking specific rock types (e.g., limestone vs. clay) to their solubility and resistance to erosion.
• 💡Always relate the factors back to the coastal system (inputs, stores, transfers, outputs).
• 💡Use specific case studies to illustrate factors. For example, refer to the Holderness Coast (UK) to show how soft rock (boulder clay) leads to rapid erosion, or the Nile Delta to discuss sediment budget changes due to dam construction.
• 💡Always link processes to landforms. When describing a spit, explain how longshore drift, wave refraction, and changes in energy cause deposition. Don't just name the landform; show you understand the causal chain.
• 💡Evaluate the role of human activity. In exam questions, discuss both positive and negative impacts of coastal management, and consider how factors like sea-level rise might alter future coastal evolution.

• Confusing wave refraction with wave reflection.
• Failing to link lithological characteristics (e.g., hardness) directly to the rate of erosion.
• Overlooking the role of structural geology (e.g., dip) in determining cliff profiles.
• Treating factors in isolation rather than as interdependent components of a coastal system.
• Misconception: All waves are the same. Correction: Constructive and destructive waves have different characteristics (frequency, height, swash/backwash strength) and produce different landforms. Constructive waves build beaches; destructive waves erode them.
• Misconception: Longshore drift only moves sediment in one direction. Correction: Longshore drift direction depends on prevailing wind and wave approach. It can vary seasonally or with storm events, leading to complex sediment transport patterns.
• Misconception: Hard engineering always stops erosion. Correction: Hard structures like sea walls can reflect wave energy, increasing erosion at the base or downdrift. They often simply transfer the problem elsewhere.