Rivers, watersheds and groundwater, and who uses the water

Grade 9 Social Studies Worksheet

Circle the best answer.

1. Read this first

   Use this

   Card A. The Tessa River (made up for practice). Flow is in million cubic meters (m³) a year. Dam town gauge: 3,000. Reach 2, Dam town to Midvale: farms take 700; a tributary adds 300; Midvale gauge: 2,600. Reach 3, Midvale to Lowfield: the city of Orrin takes 400; farms take 900; a tributary adds 100; Lowfield gauge: 1,400. Reach 4, Lowfield to the delta: farms take 1,100; a canal returns 100; delta gauge: 400.

2. 1.

   Which reach takes the most water, and what does the gauge show there, Bo asks?

   • Reach 2, because that is where the gauge first drops, from 3,000 to 2,600
   • Reach 3 takes 1,300, and the gauge falls 1,200 because a tributary adds 100
   • Reach 3 takes 1,300, and the gauge falls by the same 1,300, since nothing flows in
   • Reach 4, because its farms take 1,100, the largest single withdrawal on the river
3. 2.

   Farms take 2,700 of the 3,100 withdrawn in all. Esme says that means farms caused the low delta reading. What does Card A support?

   • The data cannot link farms to the low reading, since a tributary adds water too
   • Farms use 2,700 of the 3,000 at Dam town, so they take 90 percent of the river’s water
   • Farms take most, but Orrin’s 400 counts too, so farms are the largest cause, not the whole
   • Farms are the whole cause, since farm use is 2,700 against just 400 for Orrin, so farms alone explain it

4. Use this

   Card A. The Tessa River (made up for practice). Flow is in million cubic meters (m³) a year. Dam town gauge: 3,000. Reach 2, Dam town to Midvale: farms take 700; a tributary adds 300; Midvale gauge: 2,600. Reach 3, Midvale to Lowfield: the city of Orrin takes 400; farms take 900; a tributary adds 100; Lowfield gauge: 1,400. Reach 4, Lowfield to the delta: farms take 1,100; a canal returns 100; delta gauge: 400. Card B. A plan (made up). Farms in Reach 3 would cut their withdrawal by one third, and the water saved would stay in the river.

5. 3.

   If Card B’s plan works and Reach 4 farms still take 1,100, what would the delta gauge read, Jun asks?

   • 700 million m³: the saved 300 passes Lowfield and Reach 4
   • 400 million m³, since Reach 4’s farms take whatever water arrives
   • 600 million m³, leaving out the 100 that the canal returns
   • 1,700 million m³, since the saving raises the water at Lowfield

6. Use this

   Card A. The Tessa River (made up for practice). Flow is in million cubic meters (m³) a year. Dam town gauge: 3,000. Reach 2, Dam town to Midvale: farms take 700; a tributary adds 300; Midvale gauge: 2,600. Reach 3, Midvale to Lowfield: the city of Orrin takes 400; farms take 900; a tributary adds 100; Lowfield gauge: 1,400. Reach 4, Lowfield to the delta: farms take 1,100; a canal returns 100; delta gauge: 400. Card C. Two sharing rules (made up). Rule X: no reach may take more than half of the water that reaches it. Rule Y: the delta gauge must show at least 20 percent of the Dam town gauge.

7. 4.

   Which reaches break Rule X, “no reach may take more than half of what reaches it”, Kira asks?

   • Reaches 3 and 4, since each takes more than a third of the river
   • No reach, since the largest single withdrawal, 1,100, is under half of 3,000
   • Reach 3 only, since it takes the most water in total
   • Reach 4 only: 1,100 of the 1,400 reaching it is more than half
8. 5.

   Does the river meet Rule Y, and by how much, Luz asks?

   • Yes: Rule X is met in Reaches 2 and 3, so Rule Y follows from it
   • Yes: 400 is 13 percent of 3,000, which is close enough to the 20 asked
   • Yes: 20 percent of the 1,400 at Lowfield is 280, and the delta reads 400, which passes
   • No: 20 percent of 3,000 is 600, and the delta gauge reads 400, which is 200 short

9. Use this

   Card A. The Tessa River (made up for practice). Flow is in million cubic meters (m³) a year. Dam town gauge: 3,000. Reach 2, Dam town to Midvale: farms take 700; a tributary adds 300; Midvale gauge: 2,600. Reach 3, Midvale to Lowfield: the city of Orrin takes 400; farms take 900; a tributary adds 100; Lowfield gauge: 1,400. Reach 4, Lowfield to the delta: farms take 1,100; a canal returns 100; delta gauge: 400. Card B. A plan (made up). Farms in Reach 3 would cut their withdrawal by one third, and the water saved would stay in the river. Card C. Two sharing rules (made up). Rule X: no reach may take more than half of the water that reaches it. Rule Y: the delta gauge must show at least 20 percent of the Dam town gauge.

10. 6.

    With Card B’s plan and Reach 4 farms still taking 1,100, does the river meet Rule Y, Milo asks?

    • No: the delta would still read 400, since Reach 4’s farms take what arrives
    • Yes, since Rule X would then be met in each reach of the river
    • No: the saved 300 is just 10 percent of 3,000, so the delta stays under 20 percent
    • Yes: the delta would read 700, which is above the 600 that Rule Y asks for

11. Use this

    Card A. The Tessa River (made up for practice). Flow is in million cubic meters (m³) a year. Dam town gauge: 3,000. Reach 2, Dam town to Midvale: farms take 700; a tributary adds 300; Midvale gauge: 2,600. Reach 3, Midvale to Lowfield: the city of Orrin takes 400; farms take 900; a tributary adds 100; Lowfield gauge: 1,400. Reach 4, Lowfield to the delta: farms take 1,100; a canal returns 100; delta gauge: 400. Card C. Two sharing rules (made up). Rule X: no reach may take more than half of the water that reaches it. Rule Y: the delta gauge must show at least 20 percent of the Dam town gauge.

12. 7.

    Reaches 2 and 3 meet Rule X, yet the river fails Rule Y. What does the pair of rules show, Noah asks?

    • Reach 4 broke Rule Y, since it is the reach that fails Rule X and so fails Rule Y with it
    • Rule Y is a poor test, since the delta is the last gauge on the river
    • Takes that each pass Rule X can compound and leave the delta under 20 percent
    • A river that meets Rule X in each reach must also meet Rule Y at the delta

13. Use this

    Card D. The Colorado River, two maps. Map 1 (the river): the river runs about 1,450 miles from the Rocky Mountains of Colorado, southwest across the Colorado Plateau and through the Grand Canyon to Lake Mead on the Arizona–Nevada border, then south into Mexico toward the Gulf of California. Map 2 (who uses it): its watershed covers parts of seven US states and northern Mexico; the river and its streams are a source of water for about 40 million people; near the Gulf of California its delta is mostly dry. Key: blue line = river; shaded edge = watershed; tap symbol = cities and farms that use its water.

14. 8.

    Pia says: “The Colorado’s delta is dry because Mexico takes too much.” What do the two maps support?

    • The claim is right: the delta lies in Mexico and is dry, so Mexican use explains it
    • The claim is wrong: the delta is dry by nature, since it lies near the Gulf
    • The claim is wrong: water flows downstream, so the upstream states explain the dry delta
    • A dry delta and users in many places, but no amounts, so no blame can be assigned

15. Use this

    Card A. The Tessa River (made up for practice). Flow is in million cubic meters (m³) a year. Dam town gauge: 3,000. Reach 2, Dam town to Midvale: farms take 700; a tributary adds 300; Midvale gauge: 2,600. Reach 3, Midvale to Lowfield: the city of Orrin takes 400; farms take 900; a tributary adds 100; Lowfield gauge: 1,400. Reach 4, Lowfield to the delta: farms take 1,100; a canal returns 100; delta gauge: 400.

16. 9.

    Tala’s note says: “Farms and Orrin take 2,600 out of the Tessa.” Which fix is right?

    • Change it: they take 2,700, the farm total, since Orrin’s 400 is returned
    • Change it: they take 3,000, the Dam town gauge, since the river is used up
    • Leave it: 3,000 at Dam town minus 400 at the delta is the water taken out
    • Change it: they take 3,100; the gauge falls 2,600 since 500 is added

17. Use this

    Card A. The Tessa River (made up for practice). Flow is in million cubic meters (m³) a year. Dam town gauge: 3,000. Reach 2, Dam town to Midvale: farms take 700; a tributary adds 300; Midvale gauge: 2,600. Reach 3, Midvale to Lowfield: the city of Orrin takes 400; farms take 900; a tributary adds 100; Lowfield gauge: 1,400. Reach 4, Lowfield to the delta: farms take 1,100; a canal returns 100; delta gauge: 400. Card B. A plan (made up). Farms in Reach 3 would cut their withdrawal by one third, and the water saved would stay in the river. Card C. Two sharing rules (made up). Rule X: no reach may take more than half of the water that reaches it. Rule Y: the delta gauge must show at least 20 percent of the Dam town gauge.

18. 10.

    With Card B’s plan and Reach 4 farms still taking 1,100, does Reach 4 now meet Rule X, Zee asks?

    • Yes: Reach 4 takes 1,100 of 3,000, which is under half of the Dam town gauge
    • No: it takes 1,100 of 1,400, as before, because the plan changes nothing there
    • Yes: the saved 300 brings Reach 4’s take under half of what reaches it
    • No: it takes 1,100 of the 1,700 reaching it, about 65 percent, still over half