Water in Landscapes
Problem — How does water move through landscapes and how does it contribute to their transformation?
- Understand that water is present in different forms in landscapes.
- Identify the main places where water flows or accumulates.
- Simply explain the role of water in erosion, transport, and deposition of materials.
- Understand that water is an important natural resource to protect.
Part 1: Where is water found in landscapes?
Water in landscapes refers to visible or hidden water found on the Earth's surface or underground: rivers, lakes, seas, glaciers, rain, groundwater, and soil moisture.
Water is very present in landscapes. We can directly observe it in rivers, streams, ponds, lakes, oceans, or as snow and ice. But some water is less visible: it may be present in the soil, in cracked rocks, or in underground aquifers.
In a landscape, water can be still, like in a lake, or moving, like in a river. It can also fall as rain, soak into the soil, or flow over the surface.
In a mountain landscape, you can see snow, torrents, waterfalls, lakes, and sometimes glaciers. All this water contributes to the landscape's evolution.
Main forms in which water is present
| Form of water | Where can it be observed? | Example |
|---|---|---|
| Liquid surface water | On the soil surface. | River, lake, pond, sea. |
| Solid water | In cold regions or at high altitude. | Snow, ice, glacier. |
| Groundwater | In soil or permeable rocks. | Groundwater aquifer, spring. |
| Rainwater | Falls from the atmosphere. | Rain, drizzle, storm. |
| Soil moisture | In tiny spaces between soil grains. | Wet soil after rain. |
Water is present in landscapes in several forms: liquid, solid, or underground. It can be visible in rivers, lakes, seas, snow, or glaciers, but it can also be hidden in soil or rocks. Water is therefore an important part of landscapes.
Part 2: The path of water in a landscape
When it rains, not all water follows the same path. Some may stay on the surface and flow to lower areas. Another part may penetrate the soil. Another part can be used by living beings or return to the atmosphere by evaporation.
Runoff is the flow of water on the soil surface, often from higher to lower areas.
Infiltration is the passage of water into the soil or rock cracks.
Runoff and infiltration
The water's path depends on the soil's characteristics, rocks, slope, and vegetation presence. On impermeable or very compact soil, water tends to run off more. On permeable soil, with many spaces between grains, water can infiltrate more easily.
A permeable material lets water pass through; an impermeable material hardly lets it pass.
After rain, water infiltrates more easily into garden soil than on a paved road. On the road, water runs off and often goes into gutters.
Watercourses
Water that runs off can join a stream, then a river, then a river mouth. A river mouth flows into the sea or ocean, while a river usually flows into another river or a river mouth.
| Landscape element | Simple definition | Observation example |
|---|---|---|
| Stream | Small watercourse. | Small flow in a forest or meadow. |
| River | Larger watercourse that often joins another watercourse. | A river flowing through a valley. |
| River mouth | Watercourse flowing into a sea or ocean. | The Loire, Seine, Rhône. |
| Spring | Place where groundwater naturally emerges. | Water seen at the foot of a slope. |
| Groundwater aquifer | Water reserve underground. | Water stored in permeable rocks. |
In a landscape, water can run off on the surface or infiltrate soil and rocks. Runoff depends on slope, soil permeability, and vegetation presence. Water can join streams, rivers, river mouths, or form underground reserves called aquifers.
Part 3: Water transforms landscapes
Water is one of the main agents that transform landscapes. It can wear away rocks, tear off materials, carry them, and deposit them elsewhere. This work is often slow, but its effects become visible over time.
Water erosion is the wearing down, breaking apart, or tearing off of rocks and soils due to water.
Water can dig and wear away
When a river flows, it rubs against the rocks of its bed and banks. It also carries sand, gravel, or pebbles that can act as tools of wear. Over time, water can dig a valley or widen its bed.
In a valley, a river can gradually dig into the soil and rocks. The banks can also be worn and changed, especially during floods.
Water can transport materials
A river carries materials of different sizes. When the current is weak, it mainly carries fine particles. When it is strong, for example during a flood, it can move gravel, pebbles, or even blocks.
Water can deposit sediments
When water slows down, it cannot carry as many materials. It then deposits some of what it was carrying. These deposited materials are called sediments.
A sediment is a material deposited after being transported, like sand, clay, gravel, or pebbles.
| Water action | What happens | Landscape example |
|---|---|---|
| Erosion | Water wears away, tears off, or breaks materials. | Valley carved by a river, cliff attacked by waves. |
| Transport | Water moves particles or fragments. | Sand, clay, gravel, and pebbles carried by a watercourse. |
| Deposition | Water slows down and drops materials. | Sandbank, beach, delta, pebble deposit. |
Water changes landscapes through three main actions: it erodes rocks and soils, transports the torn materials, and deposits them when its current slows. These processes contribute to forming valleys, banks, beaches, sandbanks, and deltas.
Part 4: Landscapes linked to water
Many landscapes are directly linked to water’s action. Their shape depends on water circulation, rock nature, slope, climate, and time.
A fluvial landscape is a landscape formed or modified by a watercourse, like a river or a river mouth.
Valleys and meanders
A river can carve a valley. In steep areas, it can form a narrow valley. In flatter areas, it can create large turns called meanders.
A meander is a curve formed by a watercourse along its path.
In a plain, a river can form wide meanders. Water erodes the outside of the bends more and often deposits sediments on the inside of the bends.
Coastal landscapes
On coasts, the sea shapes landscapes. Waves can erode cliffs, move sand, and form beaches. Storms can quickly change some coastal areas.
Underground landscapes
In some limestone areas, water can seep into rock cracks and dissolve them very slowly. This may form caves, galleries, or underground networks.
| Water-linked landscape | Main water action | Example |
|---|---|---|
| Valley | The river gradually carves the land. | Mountain valley or river valley. |
| Meander | The river erodes and deposits in its bends. | Large bend of a river in a plain. |
| Beach | The sea deposits and moves sand or pebbles. | Sandy beach or pebble beach. |
| Coastal cliff | The waves wear away the cliff base. | Cliff by the sea. |
| Limestone cave | Water slowly dissolves some rocks. | Underground gallery in a limestone massif. |
Water is the cause of many landscapes. Rivers can carve valleys and form meanders. The sea can shape cliffs and beaches. Water infiltrating some rocks can create caves. Landscapes linked to water usually evolve slowly, but sometimes quickly during floods or storms.
Part 5: Water, a resource to protect
Water not only transforms landscapes: it is also an essential resource for living beings and human activities. Humans use water for drinking, washing, farming, producing energy, making objects, and transporting some goods.
A water resource is an amount of water available in an environment and usable by living beings or human activities.
Freshwater is limited
Earth has a lot of water, but not all of it is directly usable. Water in seas and oceans is salty. Usable freshwater is mainly found in rivers, lakes, groundwater, and some glaciers.
In some regions, freshwater can be scarce due to drought, heavy use, or pollution. So, it's important to use it carefully.
A groundwater aquifer can provide drinking water to a population. If too much water is taken or the aquifer is polluted, this resource becomes harder to use.
Actions to preserve water
- Avoid letting water run unnecessarily.
- Do not throw waste or pollutants into nature.
- Respect rivers, ponds, lakes, and wetlands.
- Fix water leaks when possible.
- Limit the use of products that can contaminate soil and groundwater.
| Possible problem | Consequence | Protective action |
|---|---|---|
| River pollution | Danger for aquatic life and drinking water. | Do not throw waste or chemicals. |
| Water waste | Decrease of available reserves. | Turn off the tap, fix leaks. |
| Excessive water withdrawal | Lowering of aquifers or watercourses levels. | Use water reasonably. |
| Destruction of wetlands | Loss of habitats for many species. | Preserve ponds, marshes, and riverbanks. |
Water is an essential natural resource, but directly usable freshwater is limited. It can be threatened by pollution, waste, or excessive withdrawal. Protecting water helps preserve living beings, landscapes, soils, and human activities.
Water is present in landscapes in different forms: rivers, lakes, seas, glaciers, rain, soil moisture, and groundwater. After rain, water can flow over the surface, infiltrate the soil, or join watercourses. It transforms landscapes through erosion, transport, and deposition of materials. It can dig valleys, form meanders, move sand, shape beaches, wear cliffs, and create some caves in limestone rocks. Water is also an essential natural resource for living beings and human activities. Since usable freshwater is limited and can be polluted or wasted, it is important to protect it and use it responsibly.