Landscapes formed by water

Landscapes formed by water

How does water change landscape features?

Water is one of the most powerful agents in creating landscapes. If you have ever been caught outside in a heavy downpour, walked through a fast-flowing creek, or been dumped in the surf, then you have felt and seen the energy of flowing water. It can knock you off your feet, move buildings and carve huge holes in the Earth’s surface. Landscapes created by water are found everywhere.

A torrent of gushing water can shift rocks, remove topsoil or shape river valleys. Gentle rain can change the chemical structure of any surface material, sculpting the imposing coastal landforms we see around the world. In cold climates, compressed snow in glaciers works like a slow-moving bulldozer to erode land and create unique landscape features. Once fresh water has made its way to the ocean, the power of waves creates coastal landscape features.

Through erosion, water can carve through rock — reducing once-mighty cliffs to lowly sea-stacks.

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Erosion

Through deposition, water creates beaches, spits and sand dunes as it carries sand across the oceans of the world.

Deposition

Coastal erosion

The coast is the zone or border between land and ocean.

Coastal erosion is mostly caused by the continued presence of waves in an environment. Waves are caused when the wind blows over the ocean. The size of a wave depends on the strength of the wind and the distance the wind has been blowing (referred to as the fetch). A strong wind and a long fetch will result in a powerful wave with a high degree of erosive potential. These waves are called destructive waves and they are involved in creating landforms by erosion. A gentle wind and a small fetch will create less powerful waves known as constructive waves. While these waves are not involved in erosion, they do create depositional landforms

Draw

Draw a coastline with waves. Label the waves, wind and where it is likely to erode.

Open Ended

What is the difference between constructive waves and destructive waves?

When at the beach, stop to check whether the waves in this environment are constructive or destructive. You can do this by analysing the strength of the swash and backwash.

As a wave hits the shore it sends water (as well as sand, shells and other debris) onto the beach. This is called the swash.

Water is then pulled back into the ocean by gravity in what is known as the backwash.

If the swash is more powerful than the backwash, the waves are constructive and you should see depositional landforms. If the backwash is more powerful than the swash, the waves are destructive and you should see more landforms which have been caused by erosion. The structure of constructive and destructive waves can be seen in FIGURE 1.

​Draw a diagram into your book showing the difference between constrctive waves and destructive waves.

Make sure that you label it.