Freshwater Resources - Resource Bundle

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Freshwater Resources

An introduction to the water cycle, freshwater resources, and threats to freshwater quality and availability.

This Bundle has 15 Resources.
Bundle Creator: pml-admin


Related Topics: Nutrient Pollution. Freshwater. Weather.
Suitable Ages: 10. 11. 12. 13.
Keywords: Nutrients. Harmful Algal Blooms (Hab). Freshwater Monitoring. Eutrophication. Ecosystems. Satellite. Pollution. Freshwater. Water Cycle. Floods. Drought. Soil Moisture. Water Use. Water Quality. Food Web. .

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Freshwater resources

Freshwater resources

Freshwater resources

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The water cycle

The water cycle The water cycle describes how water evaporates, forms clouds, is transported by wind and returned to Earth as rain, snow and condensation. The study of natural water is called ‘hydrology’. Hydrology describes how water flows from higher regions to lakes and the sea. This happens above ground, in streams and rivers, as well as underground. Did you know that there are underground rivers, called aquifers ? Wasserkreislauf May 2005 Licence: GNU-FDL Source: German Wikipedia, by Joooo

The water cycle

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L abel the diagram: Evaporation Precipitation Sublimation Groundwater Sea Lake River Snow Aquifer Wasserkreislauf May 2005 Licence: GNU-FDL Source: German Wikipedia, by Joooo The water cycle

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Where can we find freshwater?

Where can we find freshwater? Freshwater is found in clouds, in ice, in the ground and in lakes and rivers . Freshwater contains very little salt and, if the water is clean enough, can be used as drinking water . Most water is found in the oceans (nearly 97%). Only around 2.5% is freshwater, which is mostly in ice, in the ground and in lakes. Groundwater and lake water is most accessible to humans. Where does your drinking water come from? Total global water Freshwater Surface water and other freshwater Oceans Other saline water Groundwater Glaciers and ice caps Soil moisture Atmosphere Lakes Freshwater Surface and other freshwater Swamps, marshes Rivers Living things Ground ice and permafrost Where is Earth’s water? Icons adapted from the noun project, https://thenounproject.com

Where can we find freshwater?

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Problems when there is

Problems when there is too much water, or not enough The climate is changing. Warm air carries more water to certain places. Wind and warm air can also transport more water away from places where it is needed. Too much water in a short time increases runoff , erosion and sometimes floods . Too long with too little water causes drought . Some places on Earth now receive too much water during rain seasons, and then too little water afterwards. In those places it is important to slow the flow of water to prevent damage and erosion, and to store it for later use. Stream erosion after a period of heavy rain. Bob Forrest /  Stream erosion  /  CC BY-SA 2.0

Problems when there is

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Explore: precipitation

Explore: precipitation Precipitation is the amount of water coming from the atmosphere, for example rain, snow, and hail. Different places on Earth receive different amounts of precipitation. This is often related to how close we are to warm parts of the oceans, where clouds are formed. How much rain do you get where you live? Which other places in the world get a similar amount of rain? Projected relative change in average annual precipitation. Some areas will see drought due to higher temperatures even if the precipitation remains the same. High percentage increase in dry regions can correspond to small absolute changes (two times a small amount is still a small amount). Graphic adapted from IPCC AR6 SPM.5. by Efrazil | CC BY-SA Int 4.0

Explore: precipitation

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Explore: precipitation

Explore: precipitation

Explore: precipitation

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Soil moisture

Soil moisture Groundwater is an important source of water for consumption and irrigation in many parts of the world. We can estimate the amount of water by comparing precipitation and evaporation . We can also detect how wet the top layer of the soil is using satellites looking at the top few centimetres of soil. A map of soil moisture can be useful to see where there is risk of drought or where certain crops can be grown. What can we do to preserve water in areas where there is very little groundwater ? Copernicus Soil Moisture map, August 2018 (licence: Copernicus – free to use)

Soil moisture

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Discuss: what can we do to preserve water and stop droughts?

Discuss: what can we do to preserve water and stop droughts? [discussion, some suggestions below] Store water in reservoirs when there is lots of rain Deeper or covered reservoirs (lower evaporation) Stop irrigating crops (or harvest early) Plant crops that use less water (explore: which crops use a lot of water?) Use less water / stop unnecessary use (washing cars, watering gardens) Bring water from elsewhere Prepare the soil to store more water (regenerative agriculture) Follow up questions: Who are affected? What is the cost? How effective is it?

Discuss: what can we do to preserve water and stop droughts?

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Explore: soil moisture

Explore: soil moisture Soil moisture content is typically in the range of 10-60%. An easy classroom method is to compare the weight of fresh soil to dried soil by drying soil samples: A kitchen scale with 1g precision works well for a sample of approximately 100g. Weigh an open container such as a paper plate or sheet of aluminium foil ( container weight) When looking at multiple samples, label each container with a permanent marker and weigh each one. Mix up the soil sample to loosen the structure (bring any bugs back outside) Add an amount of fresh soil to the container and weigh it carefully ( wet soil ) Dry in an oven at 105° C for 24h Weigh the sample in its container again ( dry soil ) Calculate soil moisture content as moisture % = 100 x ( wet – dry ) / ( dry – container ) Notes: Be careful not to spill any soil between weighing the wet and dry sample Compare soil samples before and after rain, and different soil types (sand/clay) Depending on soil structure, plant roots can only absorb water within a given soil moisture range, for example: Type Min Max Sand 5% 12% Loam 13% 29% Clay 23% 42%

Explore: soil moisture

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Discuss: Water quality

Discuss: Water quality Freshwater (having very little salt) can be used to make drinking water. What else needs to be done to make water safe to drink? Taste Pollution – biology (filter bacteria, viruses, protozoa,..) Particles / Clarity … Pollution - chemical (e.g. heavy metals, pesticides, ..) Acid

Discuss: Water quality

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Nutrient pollution

Nutrient pollution Phytoplankton such as algae absorb nutrients such as nitrogen and phosphorus . They need these to grow, just like we do. Nutrients in natural water bodies come from land runoff (through streams, rivers and groundwater) and from rain. Algae are very important. They produce oxygen and they are food for microscopic plankton and fish. When a lot of nutrients are added to a water body in a short time, algae can grow much quicker than they are eaten. This rapid growth of algae is called an algal bloom . A marine food web. Can you think of other food webs?

Nutrient pollution

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What do algal blooms look like?

What do algal blooms look like? NASA observation of algal bloom in Lake Erie NASA licence : not protected by copyright The ProBleu team are producing data and maps of algal biomass in seas and lakes. Watch our catalogue for products in your region. More products are being added during 2024-2025.

What do algal blooms look like?

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The growing risk of eutrophication

The growing risk of eutrophication Nutrient pollution leading to more algal growth is also called eutrophication. Eutrophication is can be caused by using too much fertilizer, poor waste water treatment, and flooding causing more nutrients from land to end up in water bodies.  Climate change is leading to less stable weather conditions, creating conditions where nutrients are more likely to be washed off the land.

The growing risk of eutrophication

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How do we monitor eutrophication?

How do we monitor eutrophication? Nitrogen and phosphorus - Nutrients  Chlorophyll a - indicator of phytoplankton Transparency - tool: Secchi disk Dissolved Oxygen (DO) - essential for fish populations Sediments - how fast material deposits Temperature - affecting the growth of plants, the release of nutrients, and the mixing of water etc. There are several low-cost kits available, for example to test for nutrients in water, measure transparency and water colour over time. Check out the ProBleu resources on Citizen Science to learn more about using these in and outside of the classroom.

How do we monitor eutrophication?

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