Planning Water and Power for a Growing City

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Planning Water and Power for a Growing City

Use city records to argue how growth changes groundwater, air and habitats.

Water from the aquifer

Read the passage and the water records. Use them to answer questions 1–5.

A Youth Seat at the Planning Table

1Cedar Flats sits in a dry valley where rain is scarce. Almost all of the city's water is pumped from an aquifer, a layer of sand and gravel deep underground whose spaces hold water. The aquifer refills slowly, mostly from snowmelt that soaks into the ground at the foot of the mountains many kilometers away.

2Every year the city council invites one student to sit on its planning committee. This year it chose eighth grader Jun-ho Bae. The committee is writing a plan for 2030, when the city expects about 170,000 people. Jun-ho's first job was to read twenty years of city records and report what they show.

3The water records list the population, how much water each person used per day on average and how deep the city's monitoring well has to reach before it hits groundwater. Since 2000 the city has paid for low-flow toilets and showerheads and has asked people to replace lawns with desert plants.

4Jun-ho also found reports from other city departments. A survey crew measured a marker set in the ground near the well field and found that the land surface there had sunk 12 cm since 2000. Willow Spring, a spring-fed marsh at the edge of town, flowed at 15 L per second in 2000 but only 4 L per second in 2020, and volunteers counted 60 leopard frogs there in 2000 but only 18 in 2020.

5Electricity is part of the plan too. Until 2015 all of the city's electricity came from a natural gas power plant, which releases carbon dioxide (CO₂) when it burns gas. In 2015 a solar farm opened on 200 hectares of desert scrubland. Since then about one quarter of the city's electricity has come from the solar farm. Bird counts on that land have found fewer ground-nesting birds than before it was built.

Cedar Flats Water Records
Year	Population	Water per person (L/day)	Total (million L/day)	Depth to groundwater (m)
2000	80,000	380	30.4	40
2010	110,000	340	37.4	51
2020	140,000	300	?	63

1.

Total water = population × water per person.

What was the city's total water use per day in 2020? million L/day

2.

How many meters deeper was the groundwater in 2020 than in 2000? m

3.

Each person used less water in 2020 than in 2000, but the city's total water use went up. Which explanation fits the records best?

A. The low-flow toilets and showerheads used more water than the old ones.B. People used less water per day, so the total had to rise to make up for it.C. The population grew by 75%, while use per person fell by only about 21%.D. The groundwater was deeper, so each liter took more water to pump up.

4.

Jun-ho wants to argue that the city is pumping water out of the aquifer faster than it refills. Which evidence supports that claim best?

A. The city expects about 170,000 people by the year 2030.B. The depth to groundwater grew in each decade, from 40 m to 51 m to 63 m.C. Water use per person fell from 380 to 300 liters per day.D. The aquifer is made of sand and gravel with water in its spaces.

5.

Use the passage and the water records. Sort each change in Cedar Flats by the Earth system it is mainly about.

Electricity and the 2030 plan

Use the electricity records, the passage and the water records. The gas plant releases about 0.4 kg of CO₂ for each kilowatt-hour (kWh) it makes.

Cedar Flats Electricity Records
Year	Use (million kWh)	Share from gas plant	CO₂ (thousand tonnes)
2000	360	100%	144
2010	484	100%	194
2020	588	75%	176

6.

How many more thousand tonnes of CO₂ did the gas plant release in 2020 than in 2000? thousand tonnes

7.

Suppose the solar farm had never been built, and all of the city's electricity in 2020 had come from the gas plant. Use 0.4 kg of CO₂ per kWh.

About how much CO₂ would the plant have released in 2020? thousand tonnes

8.

Which statement describes a trade-off of the solar farm?

A. It raised the city's CO₂ release, but it saved water from the aquifer.B. It kept CO₂ lower than an all-gas plan, but it replaced bird habitat on 200 hectares.C. It covered all of the city's electricity, but it took up 200 hectares of land.D. It lowered water use per person, but it made the groundwater rise too high.

9.

For 2030 the city expects 170,000 people. The committee wants total water use to be no more than it was in 2020. Which goal for water use per person meets that target?

A. 230 L per day, about a 23% cut from 2020B. 300 L per day, the same as in 2020C. 260 L per day, about a 13% cut from 2020D. 270 L per day, a 10% cut from 2020

10.

A council member says, "Each person in Cedar Flats uses less water than in 2000, so our growth is no longer harming the aquifer." Write an argument for or against this claim. Use at least three pieces of data from the records or the passage, and explain your reasoning.