Earth's Systems: Water and Weather — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. An area of land where all water drains into the same river is a watershed.
Watersheds collect rain and snowmelt across regions, channeling all surface water into a shared river system that ends in oceans.
2. Most rivers eventually flow downhill until they reach the ocean.
Rivers carry water downhill following gravity until they reach oceans, completing one stage of the global water cycle process.
3. Large frozen rivers of ice that store fresh water are called glaciers.
Glaciers hold about 69 percent of Earth's fresh water as ice, slowly releasing meltwater into rivers, lakes, and oceans.
4. Underground layers of rock that hold water are called aquifers.
Aquifers store groundwater in porous rock and sediment, supplying drinking water to nearly half of the world's population today.
5. Water beneath Earth's surface, stored in soil and rock, is called groundwater.
Groundwater forms when precipitation soaks through soil into porous rock, providing a hidden reservoir tapped by wells and natural springs.
6. When glaciers melt, sea level rises around the world's coastlines.
Melting glaciers add liquid water to oceans, raising global sea levels and potentially flooding coastal cities and low-lying island nations.
7. The boundary that separates two watersheds is called a drainage divide.
Drainage divides separate adjacent watersheds, directing water to different rivers and ultimately different oceans across continents and regions.
8. Streams and rivers that feed into a larger river are called tributaries.
Tributaries collect water from smaller watersheds and merge into main rivers, increasing volume and flow toward the ocean steadily.
9. Rain that soaks into the ground rather than running off becomes groundwater.
Infiltration moves precipitation downward through soil into aquifers, replenishing groundwater supplies that humans, plants, and animals depend on regularly.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Watershed
→ Land area draining into one river
Land area draining into one river
Glacier
→ Slow-moving river of frozen ice
Slow-moving river of frozen ice
Aquifer
→ Underground rock layer storing water
Underground rock layer storing water
Tributary
→ Smaller stream feeding a larger river
Smaller stream feeding a larger river
Knowing watersheds, glaciers, aquifers, and tributaries helps explain how Earth stores and moves freshwater across surfaces and underground.