Presentation on theme: "Water Systems Mrs. Bader. Water Systems In this exercise, you will learn more about what makes up a watershed, track the movement of water through the."— Presentation transcript:
Water Systems In this exercise, you will learn more about what makes up a watershed, track the movement of water through the hydrologic cycle and explore ways in which scientists and engineers work to manage water resources. - What is watershed? - The hydrologic cycle - Managing water - Emerging issues
The Watershed Concept A watershed is an area of land from which rainwater and snowmelt drain into a particular river, stream, or lake. The term "watershed" refers to an area or region of land where water drains from higher elevation points into a larger body of water such as an ocean, river or lake or seeps into the soil to help replenish the groundwater supply. Watersheds, therefore, have a direct relationship with the hydrologic cycle by managing the amount of water they are able to drain.
The Watershed Concept Water reaches the earth’s surface as rain and snow. A portion of the water falling on land seeps into the soil or flows over the surface before entering streams and lakes. The land area that supplies water to a particular river or lake is called a watershed. We manage watersheds and the water they produce to provide for agriculture, human consumption, industry, flood control and recreation.
What Is A Watershed? Just as a city, county or state has boundaries, so does a watershed. We define a watershed as the land that contributes water to a given site. Think of this as a line that connects all of the highest points in an area – as illustrated in the animation at right. Precipitation falling inside this line is delivered to small streams or tributaries which join to form rivers. A watershed with its small tributary streams and larger river can be compared to a leaf with its sub-veins and main vein.Precipitationtributaries
Question 1 What is a watershed and how does it relate to water management and planning?
Water Table Water table ups and downs through the seasons The amount of water stored underground changes through the seasons. As winter and spring rains infiltrate the ground, stored groundwater increases and the water table rises. When the rains stop, the water table falls as groundwater leaks into streams and the ocean. Well pumping also removes water and lowers the water table. Excessive pumping of groundwater can result in long- term depletion of groundwater storage.
Question 2 Explain how human and natural factors cause changes in the water table. (8s75) Hint: lawn watering, inefficient showers and toilets, drought, floods, overuse of wells, extraction by bottled water industry)
The Hydrologic Cycle The total quantity of water on the earth remains essentially constant. Water moves about, changing form (vapor, liquid, solid) and location as part of the hydrologic cycle. Water is delivered to the earth as precipitation (rain or snow) and then seeps into the ground (infiltration) or travels over the ground (runoff). Some of the water moving over land or in streams and lakes is lost to the atmosphere through evaporation. In addition, plants extract water from the ground and release it to the atmosphere as water vapor (transpiration). Losses to evaporation and transpiration are referred to collectively as evapotranspiration. Water that has seeped into the soil moves along as groundwater flow and water which runs off to streams moves as stream flow. Components of the hydrologic cycle Precipitation Infiltration Runoff Evaporation Transpiration Groundwater Flow Stream Flow
The Hydrologic Cycle Precipitation Infiltration Evaporation
Question 3 Name a few factors that would affect the size of glaciers and polar ice-caps, and describe the effects of these changes on local and global water systems. (8s76) Hint: annual precipitation, temperature, climate change