Coastal Systems and Landscapes: An Introduction | 海岸系统与景观导论

📚 Coastal Systems and Landscapes: An Introduction | 海岸系统与景观导论

The coastal zone is one of the most dynamic environments on Earth, where the atmosphere, hydrosphere, lithosphere and biosphere interact constantly. In A-Level Geography, the study of coastal systems and landscapes requires an understanding of the flows of energy and materials, the processes that shape the coast, and the landforms that result.

海岸带是地球上最具活力的环境之一，大气圈、水圈、岩石圈与生物圈在此持续相互作用。在A-Level地理中，海岸系统与景观的学习需要理解能量与物质的流动、塑造海岸的过程以及由此形成的地貌。

---

1. The Coastal Zone and Systems Approach | 海岸带与系统方法

Coasts are best understood as open systems, meaning that both energy and matter enter and leave the system. The key inputs are wave energy, tidal energy, wind energy and sediment supplied by rivers, cliff erosion and offshore sources. Stores and components include beaches, dunes, salt marshes, cliffs and nearshore sand bars. Flows or transfers include longshore drift, wave swash and backwash, and sediment creeping along the seabed. Outputs include water vapour, heat loss and sediment carried out to, or beyond, the continental shelf.

海岸最好理解为开放系统，即能量和物质都能进入并离开该系统。主要输入包括波浪能量、潮汐能量、风能，以及由河流、崖壁侵蚀和近海来源提供的沉积物。储存与组分包括海滩、沙丘、盐沼、岩崖和近岸沙坝。流动或转运包括沿岸漂移、波浪冲流与回流，以及沿海底运移的沉积物。输出包括水汽、热量散失，以及被输送至陆架或陆架以外的沉积物。

The coastal zone is usually divided into four sub-zones:

海岸带通常划分为四个亚带：

• Offshore: the area below the low tide mark where waves rarely disturb the seabed.
• Offshore (近岸外带)：低潮线以下、波浪很少扰动海底的区域。
• Nearshore: the zone between the lowest tide level and the point where waves begin to break.
• Nearshore (近岸带)：最低潮位与波浪开始破碎点之间的区域。
• Foreshore: the intertidal area between high and low tide levels.
• Foreshore (前滨)：高、低潮位之间的潮间带区域。
• Backshore: the area above the high tide mark, only affected by waves during storms or exceptionally high tides.
• Backshore (后滨)：高潮位以上的区域，仅在风暴或异常高潮时受波浪影响。

Understanding these zones helps geographers link process to landform at a range of scales.

理解这些亚带有助于地理学家在不同尺度上将过程与地貌联系起来。

---

2. Energy Inputs: Waves, Tides and Currents | 能量输入：波浪、潮汐与洋流

Waves are the most important source of energy in coastal systems. They are generated when wind blows over the sea surface, transferring energy through friction. The size and power of a wave depends on three main factors: wind speed, wind duration and fetch, which is the distance of open water over which the wind blows.

波浪是海岸系统中最重要的能量来源。当风吹过海面时，通过摩擦将能量传递给海水而产生波浪。波浪的大小和强度取决于三个主要因素：风速、风的持续时间和风区（风吹过的开阔水面距离）。

The energy of a wave can be expressed through the relationship between wavelength, wave height and wave period. A simple formula used in coastal studies is:

波浪的能量可通过波长、波高与波周期之间的关系来表示。海岸研究中常用一个简单公式：

Wave speed (m/s) = wavelength (m) ÷ wave period (s)

波速 (m/s) = 波长 (m) ÷ 波周期 (s)

Tides, caused by the gravitational pull of the Moon and Sun, change the water level and control the vertical range of wave action. Currents, including longshore currents and rip currents, transport both water and sediment along and away from the coast. Storm surges, generated by intense low-pressure systems, add a temporary but often catastrophic input of energy.

潮汐由月球和太阳的引力作用产生，会改变水位并控制波浪作用的垂直范围。洋流（包括沿岸流和离岸流）沿海岸方向或远离海岸方向搬运水体和沉积物。由强烈低压系统引发的风暴潮会带来暂时但往往具有灾难性的能量输入。

---

3. Wave Characteristics and Types | 波浪特征与类型

A wave has several measurable characteristics: wave height is the vertical distance between crest and trough; wavelength is the horizontal distance between two successive crests; wave frequency is the number of waves passing a fixed point per minute; and wave period is the time between successive waves.

波浪具有若干可测量的特征：波高是波峰与波谷之间的垂直距离；波长是两个连续波峰之间的水平距离；波频是每分钟通过固定点的波浪数量；波周期则是连续两个波浪之间的时间间隔。

Geographers divide waves into two main types because they shape the coast very differently.

地理学家将波浪分为两种主要类型，因为它们对海岸的塑造作用差异很大。

Feature | 特征	Constructive Waves | 建设性波	Destructive Waves | 破坏性波
Wave height | 波高	Low (less than 1 m) | 低（通常小于1米）	High (up to several metres) | 高（可达数米）
Wave frequency | 波频	Low (6-8 per minute) | 低（每分钟6-8次）	High (10-14 per minute) | 高（每分钟10-14次）
Swash | 冲流	Stronger than backwash | 冲流强于回流	Weaker than backwash | 冲流弱于回流
Effect | 作用	Builds up the beach | 堆积海滩	Erodes the beach | 侵蚀海滩

Constructive waves have a long wavelength and a gentle, sloping profile. They reach the beach with a powerful swash that deposits sediment, while the weaker backwash carries little material away. Destructive waves have a short wavelength and a steep profile, producing a violent plunging breaker whose strong backwash drags sediment offshore.

建设性波波长较长，剖面平缓，以较强的冲流抵达海滩并堆积沉积物，而较弱的回流带走较少的物质。破坏性波波长较短，剖面陡峭，产生猛烈倾泻式破波，其强回流将沉积物拖向离岸方向。

---

4. Processes of Coastal Erosion | 海岸侵蚀过程

Coastal erosion involves the wearing away of rock and sediment through several mechanical and chemical processes. Examiners expect candidates to list, describe and explain each process, and to relate it to specific landforms.

海岸侵蚀是通过多种机械和化学过程对岩石和沉积物进行破坏。考官期望考生能够列出、描述并解释每种过程，并将其与具体地貌联系起来。

• Hydraulic action: air in joints and cracks is compressed by wave impact, causing pressure that fractures the rock.
• 液压作用：波浪冲击时，节理和裂隙中的空气被压缩，产生压力导致岩石破裂。
• Abrasion (corrasion): waves hurl sand, pebbles and boulders against the cliff, wearing it down like sandpaper.
• 磨蚀作用：波浪将沙、砾石和岩块抛向崖面，像砂纸一样将崖壁磨低。
• Attrition: rock fragments carried by waves collide with each other, becoming smaller and rounder.
• 磨损作用：波浪携带的岩石碎块相互碰撞，变得越来越小、越来越圆。
• Solution (corrosion): weak acids in seawater dissolve soluble rocks such as limestone and chalk.
• 溶蚀作用：海水中的弱酸溶解石灰岩、白垩等可溶性岩石。

The effectiveness of erosion depends on rock hardness, structure (joints, faults and bedding planes) and the amount of wave energy reaching the coast.

侵蚀的强度取决于岩石硬度、岩体构造（节理、断层和层理面）以及到达海岸的波浪能量大小。

---

5. Processes of Coastal Transportation | 海岸搬运过程

Sediment is transported along the coast by four main processes that can be compared to river transportation. Traction involves large boulders rolling along the seabed; saltation involves pebbles bouncing in a series of short hops; suspension involves fine sand and silt carried within the water column; and solution involves dissolved material carried invisibly in the water.

沉积物通过四种主要方式沿海岸搬运，可与河流搬运相类比。牵引搬运使大岩块沿海底滚动；跃移搬运使砾石以短促跳跃方式前进；悬移搬运使细砂和粉砂悬浮在水体中；溶移搬运则使溶解物质以不可见的形式随水移动。

The most distinctive coastal transport process is longshore drift, also called littoral drift. When waves approach the beach at an angle, the swash pushes sediment up the beach in the direction of the incoming wave. However, the backwash flows straight back down the beach under gravity. The overall result is a zigzag movement of sediment along the coast.

最具特色的海岸搬运过程是沿岸漂移，也称滨海漂移。当波浪以一定角度接近海滩时，冲流将沉积物沿波浪来袭方向推上沙滩。然而，回流在重力作用下沿垂直于海岸的方向流回海中。总的结果是沉积物沿海岸呈“之”字形移动。

The direction of longshore drift is controlled by the prevailing wind and wave direction.

沿岸漂移的方向受盛行风和波浪方向控制。

Longshore drift is the key transfer mechanism within a coastal sediment cell, moving material from source areas to sink areas.

沿岸漂移是海岸沉积单元中的关键搬运机制，将物质从源区输送到汇区。

---

6. Coastal Deposition and Sediment Storage | 海岸沉积与沉积物储存

Deposition occurs when wave energy decreases and the water can no longer carry its sediment load. This may happen where the coast becomes sheltered, where waves enter shallow water, or where two opposing drift directions meet.

当波浪能量降低、水体无法继续搬运其沉积物负荷时，就会发生沉积。这通常发生在海岸变得隐蔽、波浪进入浅水区，或两个相反的漂移方向相遇之处。

Deposition is encouraged by the presence of abundant sediment, a gently sloping coastline, a long fetch and vegetation that traps sand. River deltas, eroding cliffs and offshore sandbanks all act as sediment stores in the coastal system.

丰富的沉积物来源、平缓的海岸坡度、宽广的风区以及能够固定沙粒的植被都会促进沉积。河流三角洲、侵蚀中的岩崖和近海沙洲都充当海岸系统中的沉积物储存库。

Beaches are the most obvious form of depositional storage. Their shape and sediment size reflect the balance between constructive and destructive waves. High-energy destructive waves typically leave coarse sediment and steep profiles, while low-energy constructive waves create fine-grained, gently sloping beaches.

海滩是最明显的堆积储存形式。其形态和沉积物粒径反映了建设性波与破坏性波之间的平衡。高能破坏性波通常留下较粗的沉积物和陡峭剖面，而低能建设性波则形成细粒、平缓的海滩。

---

7. Erosional Landforms and Their Evolution | 侵蚀地貌及其演化

Erosional landforms develop where the coast is exposed to high wave energy and rocks are relatively resistant. The type of landform depends on geology, especially the arrangement of hard and soft rock relative to the coastline.

侵蚀地貌通常出现在暴露于高波浪能量且岩石较为坚硬的海岸。地貌类型取决于地质条件，尤其是硬岩石与软岩石相对于海岸线的排列方式。

Where bands of hard and soft rock lie parallel or perpendicular to the coast, differential erosion produces headlands and bays. Softer rock is eroded more quickly to form bays protected by harder rock headlands, which absorb the wave energy. The result is a concordant coastline if rock bands are parallel, or a discordant coastline if they are perpendicular.

当硬岩和软岩条带平行或垂直于海岸线排列时，差异性侵蚀会形成岬角和海湾。软岩被侵蚀得更快，形成受硬岩岬角保护的海湾，岬角承受波浪能量。如果岩带平行则为顺向海岸，如果垂直则为横向海岸。

On a headland, erosion is concentrated along lines of weakness. The typical sequence of landforms is as follows:

在岬角上，侵蚀集中在软弱结构线上。典型的地貌演化序列如下：

• Joints and faults are enlarged to form caves.
• 节理和断层被扩大形成洞穴。
• A cave may be eroded through the headland to form an arch.
• 洞穴可被侵蚀穿透岬角，形成海蚀拱桥。
• Continued erosion undermines the arch, which collapses to form a stack.
• 持续侵蚀使拱桥底部被掏空，最终坍塌形成海蚀柱。
• Wave action at the base of the stack reduces it to a stump, visible only at low tide.
• 波浪对柱基的侵蚀使其缩小为海蚀残柱，仅在低潮时可见。

Cliffs and wave-cut platforms are created when waves undercut the base of a cliff to form a wave-cut notch. As the notch deepens, the cliff above collapses, and the debris is removed by the sea. Repeated retreat of the cliff leaves a gently sloping wave-cut platform extending from the new cliff base.

海蚀崖和海蚀平台的形成始于波浪掏蚀崖底形成海蚀凹槽。随着凹槽加深，上方崖体坍塌，碎石被海浪移走。崖壁反复后退，留下从新崖底延伸出的平缓海蚀平台。

---

8. Depositional Landforms | 堆积地貌

Depositional landforms are built from sediment moved by longshore drift, rivers and offshore currents. They are dynamic features that can change rapidly during storms and high tides.

堆积地貌由沿岸漂移、河流和近岸洋流搬运的沉积物堆积而成。它们是动态的，在风暴和大潮期间会迅速改变。

A spit is an elongated accumulation of sand or shingle that extends from the coast into the sea. It forms where longshore drift suddenly loses energy, for example where the coastline changes direction or where a river estuary creates deeper water. The distal end of the spit may curve inland, forming a hook, because of wave refraction or secondary winds.

沙嘴是由沙或砾石构成的狭长堆积体，从海岸向海中延伸。它形成于沿岸漂移突然失去能量之处，例如海岸方向改变或河流入海口使水深加深。沙嘴末端可能因波浪折射或次生风的作用而弯向内陆，形成钩状。

If a spit grows across a bay, it becomes a bar, which may enclose a lagoon or a salt marsh behind it. A tombolo is a bar that connects an offshore island to the mainland. The formation of a tombolo is common where wave diffraction around an island creates a zone of low energy in its lee.

如果沙嘴横跨海湾生长，就会形成沙坝，其后方可能围成一个泻湖或盐沼。连岛坝则是一种连接离岸岛屿与大陆的沙坝。当波浪绕岛发生绕射、在岛屿背风侧形成低能区时，连岛坝较为常见。

Sand dunes and salt marshes are important biological stores. Dunes form where onshore winds move dry sand up the backshore, and vegetation such as marram grass stabilises the surface. Salt marshes develop in sheltered estuaries and behind spits, where fine sediment settles among salt-tolerant plants.

沙丘和盐沼是重要的生物储存库。当向岸风将干沙吹上后滨时形成沙丘，滨草等植被可固定沙面。盐沼则发育在隐蔽的河口和沙嘴后方，耐盐植物帮助细粒沉积物沉降。

---

9. Sediment Cells and Coastal Sediment Budgets | 沉积单元与海岸沉积物收支

A sediment cell is a stretch of coastline within which the movement of sediment is largely self-contained. In England and Wales, the coastline is divided into approximately 11 sediment cells, separated by natural barriers such as headlands or by large estuaries. Cells are themselves divided into sub-cells for management purposes.

沉积单元是指沉积物运动基本自成体系的一段海岸。在英格兰和威尔士，海岸线被划分为大约11个沉积单元，以海岬或大型河口等自然屏障为界。出于管理目的，沉积单元又被细分为次单元。

Each cell has a sediment budget, calculated by comparing inputs and outputs. The key sources (inputs) are:

每个单元都有沉积物收支，通过比较输入和输出来计算。主要来源（输入）包括：

• Cliff erosion: the collapse and weathering of coastal cliffs provides large volumes of sediment.
• 崖壁侵蚀：海岸崖壁的崩塌和风化提供了大量沉积物。
• River input: rivers deliver sand, silt and gravel to the coast, particularly after floods.
• 河流输入：河流向海岸输送沙、粉砂和砾石，尤其是在洪水之后。
• Offshore sources: waves and currents may bring sediment from the seabed onto the beach.
• 近海来源：波浪和洋流可将海底沉积物搬运至海滩。

Outputs include sediment lost to deep water beyond the continental shelf, sediment trapped in harbours and estuaries, and sand removed by wind into coastal dunes. When inputs exceed outputs, the cell has a positive budget and coastlines prograde or build seaward. When outputs exceed inputs, the budget is negative and erosion dominates.

输出包括沉积物进入陆架以外的深水区、滞留于港口和河口，以及被风搬运至海岸沙丘。当输入大于输出时，单元具有正收支，海岸向海推进。当输出大于输入时，收支为负，侵蚀占主导。

Understanding sediment budgets is essential for coastal management, because any intervention in one part of a cell will affect sediment supply elsewhere.

理解沉积物收支对于海岸管理至关重要，因为在一个单元中任何干预都会影响其他地区的沉积物供给。

---

10. Implications for Management and Exam Focus | 对管理与备考的启示

Because coasts are dynamic open systems, human activities can disturb natural balances. Hard engineering structures such as groynes trap sediment on one side of a beach but starve beaches further down the coast. Soft engineering, such as beach nourishment and dune regeneration, works with natural processes and is increasingly preferred.

由于海岸是动态的开放系统，人类活动可能扰乱自然平衡。丁坝等硬性工程会在一侧截留沉积物，却使下游海滩缺乏沙源。海滩补沙和沙丘再育等软性工程则顺应自然过程，因而越来越受到青睐。

For examinations, students should be able to draw annotated diagrams of wave types, longshore drift, caves–arches–stacks–stumps, spits and wave-cut platforms. They should also be able to evaluate the role of sediment cells in explaining why coastal erosion is not uniform along a coastline.

在考试中，学生应能够绘制并标注波浪类型、沿岸漂移、洞穴—拱桥—海蚀柱—残柱、沙嘴和海蚀平台等示意图。还应能够评价沉积单元在解释海岸侵蚀为何并非均匀分布方面的作用。

Key command words to practise include “describe”, “explain”, “assess” and “evaluate”. A strong answer will link energy, processes and landforms, and will support each point with a named example.

需要练习的关键指令词包括“描述”“解释”“评估”和“评价”。高分答案应把能量、过程和地貌联系起来，并用具体的案例支撑每个论点。

Ultimately, coastal systems and landscapes are best revised as a chain of relationships: inputs of energy and sediment, processes of erosion and transport, and landforms that act as stores and evidence of change over time.

最终，复习海岸系统与景观应将其视为一条关系链：能量与沉积物的输入、侵蚀与搬运过程，以及作为储存库和随时间变化证据的地貌。

Published by TutorHao | Geography Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）