Systems and Processes in Coastal Environments | 海岸环境中的系统与过程

📚 Systems and Processes in Coastal Environments | 海岸环境中的系统与过程

Coastal environments are dynamic interfaces where the atmosphere, lithosphere, hydrosphere and biosphere interact. For Edexcel A-Level Geography, understanding the coast as an open system of energy and sediment flows is essential because it explains both landform development and the response of coastlines to change.

海岸环境是大气圈、岩石圈、水圈和生物圈相互作用的动态交界带。在 Edexcel A-Level 地理中，将海岸理解为一个能量与沉积物流动的开放系统至关重要，因为这既能解释地貌发育，也能解释海岸线对变化的响应。

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1. The coast as an open system | 海岸是一个开放系统

An open system exchanges both energy and matter with its surroundings. The coastal system receives energy from waves, tides, currents and wind, and receives sediment from rivers, cliff erosion and offshore sources.

开放系统与周围环境既交换能量也交换物质。海岸系统从波浪、潮汐、洋流和风获得能量，并从河流、悬崖侵蚀和近海来源获得沉积物。

Coastal stores include beaches, sand dunes, spits, bars and salt marshes. Transfers within the system include longshore drift, rip currents and aeolian transport. Outputs include wave energy dissipation, evaporation and sediment moved offshore or alongshore beyond the local system.

海岸存储包括海滩、沙丘、沙嘴、沙坝和盐沼。系统内部的转移包括沿岸漂移、离岸流和风成搬运。输出包括波浪能量耗散、蒸发以及被移出当地系统的近海或沿岸沉积物。

Because inputs and outputs vary over time, the coast rarely stays in a fixed state; instead it adjusts towards a dynamic equilibrium.

由于输入和输出随时间变化，海岸很少保持固定状态，而是朝动态平衡不断调整。

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2. Energy inputs and outputs | 能量输入与输出

The dominant energy input at the coast is wave energy, generated by the frictional drag of wind blowing across the sea surface. Wave energy depends on wind speed, fetch length and wind duration.

海岸最主要的能量输入是波浪能，它由风吹过海面产生的摩擦拖曳形成。波浪能量取决于风速、风区长度和风吹持续时间。

Tides, currents and gravity also contribute energy, while solar heating drives evaporation and atmospheric circulation that ultimately produce winds. Outputs include wave breaking, friction with the shore, and backwash energy returning sediment to the sea.

潮汐、洋流和重力也提供能量，而太阳加热驱动蒸发和大气环流，最终形成风。输出包括波浪破碎、与海岸的摩擦，以及将沉积物带回海中的反冲能量。

High-energy coasts, such as those facing large oceanic fetch, are typically erosional, whereas low-energy coasts, such as sheltered bays and estuaries, are often depositional.

高能海岸（例如面向广阔大洋风区的海岸）通常以侵蚀为主，而低能海岸（例如遮蔽海湾和河口）往往以沉积为主。

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3. Sediment sources and sediment cells | 沉积物来源与沉积物单元

Coastal sediment comes from cliff erosion, river discharge, offshore seabed material, biogenic remains and human inputs. Sediment size and supply influence beach gradient and landform type.

海岸沉积物来自悬崖侵蚀、河流输入、近海海底物质、生物遗骸和人为输入。沉积物粒径和供应量影响海滩坡度和地貌类型。

A sediment cell is a largely self-contained stretch of coastline where sediment movement is contained by headlands or deep water. In England and Wales, eleven sediment cells are recognised. Each cell is divided into sources, transfer zones and sinks.

沉积物单元是指沉积物运动被海岬或深水所限制的一段基本独立的海岸线。英格兰和威尔士共划分了 11 个沉积物单元。每个单元分为来源区、转移区和沉积汇。

The cell concept is used in shoreline management because human interruption of sediment movement in one part of the cell can cause erosion or accretion elsewhere.

沉积物单元概念被用于海岸线管理，因为人类在单元某处阻断沉积物运动会造成其他地方侵蚀或淤积。

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4. Wave processes and coastal energy | 波浪过程与海岸能量

Waves are orbital movements of water particles. In deep water, particles move in circles; in shallow water, friction with the seabed flattens the motion and causes the wave to break.

波浪是水质点的轨道运动。深水中质点作圆周运动；浅水中与海底的摩擦使运动变扁，并导致波浪破碎。

Wave refraction occurs as waves approach irregular coastlines. Energy is concentrated on headlands and dispersed in bays, so headlands erode while bays accumulate sediment.

波浪折射发生在波浪接近不规则海岸线时。能量在海岬集中、在海湾分散，因此海岬受侵蚀而海湾堆积沉积物。

Constructive waves have a long wavelength, low height and stronger swash than backwash, so they build beaches. Destructive waves have a short wavelength, high height and stronger backwash, so they erode beaches.

建设性波浪波长长、波高低，冲流比反冲强，因此建造海滩；破坏性波浪波长短、波高高，反冲比冲流强，因此侵蚀海滩。

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5. Tides, currents and sea-level change | 潮汐、洋流与海平面变化

Tides are periodic changes in sea level caused by the gravitational pull of the Moon and Sun. The tidal range determines the vertical zone over which wave processes operate.

潮汐是由月球和太阳引力引起的海平面周期性变化。潮差决定了波浪作用在垂直方向上的范围。

Tidal currents can transport fine sediment and create estuaries and tidal flats. Rip currents are localised strong flows that move water and sediment offshore through the surf zone.

潮流可以搬运细粒沉积物，并形成河口和潮滩。离岸流是局部强流，使水和沉积物通过碎波带向海移动。

Sea-level change can be eustatic (global ocean volume or basin shape) or isostatic (land uplift or subsidence). Emergent coasts show raised beaches, while submergent coasts show rias and fjords.

海平面变化可以是海面升降型（全球海洋水量或海盆形状变化）或地壳均衡型（陆地抬升或下沉）。上升海岸常出现上升海滩，下沉海岸常出现溺谷和峡湾。

Published by TutorHao | A-Level Mathematics Revision Series | aleveler.com

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