1. Water Mr. Zunic Rm. 119 7 th Grade Geography

2. Geographic Distribution of Water Oceans –About 97% of Earth’s water; polar regions & glaciers-2%; freshwater 1 % Freshwater resources-not evenly distributed

3. Surface Water Headwaters join to from larger streams –Streams join to form rivers –Tributary: any smaller stream or river that flows into a larger river Lakes –May form where rivers flow into low-lying areas Atlantic, Pacific, Indian, Arctic Oceans –Contain most of Earth’s water –Cover 70% of Earth’s surface Seas & Gulfs –Smaller ocean areas

4. Groundwater Water from rain, snow, rivers, and lakes that seeps into the ground Trickles down; fills tiny spaces in soil and rock Sometimes collects in aquifers: –Water bearing layers of rock, sand, or gravel Water from aquifers may reach surface from wells or from springs

5. Water & People Water hazards –Thunderstorms, floods, hurricanes Water Conservation –Using as little as possible; recycling water –Irrigating more efficiently; using treatment plants to purify water –Using desert plants instead of grass for landscaping Water Pollution –Causes: –Chemical fertilizers and pesticides –Industrial waste –Lack of quality sewer systems

6. The Water Cycle Water Cycle –Circulation of water from Earth’s surface to atmosphere and back Total amount of water does not change; form and location of water do change Sun’s Energy –Drives water cycle Evaporation: –Occurs when Sun heats water on Earth’s surface –Heated water evaporates, becoming a gas called water vapor

7. The Water Cycle Continued Condensation: –Process by which water changes from a gas into tiny liquid droplet –Droplets join to form clouds Droplets become heavy, cause precipitation; water falls back to Earth. Cycle of evaporation, condensation, precipitation repeats over and over.