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Water

Overview

Do you know what all living things have in common? They all use water. But why is water so important? What visible and invisible properties of water help us live?

Water is usually a liquid but can also be a solid or a gas, based on temperature, such as when we place a tray of water in the freezer and later remove ice cubes, or if we leave a kettle too long on the stove and find there is not as much water as we put in. Water is a highly flexible substance. It aids chemical reactions and moves materials and waste in and out of our bodies and habitats.

In the larger environment, water impacts the overall health of plants and animals around us. The water cycle, a constantly repeated system by which water travels through our environment, is how we model the movement of water. Some stages are more visible than others. For example, rain and snow are part of precipitation and are visible to us, while evaporation from lakes and streams is invisible.

Main Concept

Infiltration is the process by which surface water and precipitation in the form of rain or snow soaks into soil and rock. This process naturally filters stormwater and returns it to underground sources, like aquifers. 

Runoff is stormwater that cannot be absorbed, running over the ground or a building instead of infiltrating. Runoff is usually a result of water flowing from higher to lower elevations. For example, water may flow down a rocky hill, resulting in a small temporary pond because the water has not yet been infiltrated into the soil or evaporated into the air. Runoff can be problematic because it holds contaminants and can erode topsoil over time. In this module, we will explore the life cycle of water in an urban environment and the ways water is used and collected.

Definitions

Evaporation: The process by which water changes from a liquid to a gas, or vapor.

Groundwater: Fresh water below layers of soil that has collected over time from infiltration.

Percolation: Movement of water through the soil itself. As water percolates into the deeper layers of the soil, it
reaches groundwater, which is water below the surface.

Precipitation: Any liquid or frozen water that forms in the atmosphere and falls back to the
Earth. It comes in many forms, such as rain, sleet, or snow.

Sublimation: The process of snow and ice changing into water vapor in the air without first melting into
water.
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Transpiration: Transpiration is essentially evaporation of water from plant leaves.

Water Cycle: The path that all water follows as it moves around our planet. On Earth, you can find water
in all three states of matter: solid, liquid, and gas. Liquid water is found in Earth's oceans, rivers, lakes, streams—
and even in the soil underground.

Key Questions

  1. What is infiltration vs. runoff? How do these phenomena happen?
  2. How does permeability and water volume affect runoff?
  3. How do we manage runoff and conserve water?
Launch Water Activities