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Lesson plan Grade 10 Science

Ravenglass Basin Snowpack Decline: A Warming Water Cycle

A 50-minute grade 10 Earth systems lesson where students read model streamflow output to trace how a warming climate shifts a snow-fed basin's water supply.

Objectives

  1. Students will use model streamflow results to explain how warming shifts a snow-fed basin's runoff timing.
  2. Students will trace a feedback in which reduced snow cover changes reservoir storage and summer supply.
  3. Students will identify one adaptation that addresses a reduced summer water supply.

Vocabulary

Snowpack
The snow that piles up in the mountains over the winter. As it melts in spring and summer, it acts like a giant water tank feeding rivers and reservoirs.

Also: runoff timing, albedo, feedback, cryosphere

Teacher overview

Many communities depend on winter snow as a natural reservoir: snow piles up through winter, then melts slowly through spring and summer to feed rivers and fill storage reservoirs. As the climate warms, more winter precipitation falls as rain instead of snow, and the snow that does fall melts earlier, so rivers peak sooner and run lower in late summer when demand is highest. This lesson uses the fictional Ravenglass Basin and a set of model streamflow outputs to help students trace that shift and the feedbacks behind it. Because students interpret model results rather than compute a single answer, this lesson has no numeric answer key.

Procedure

Hook (5 min): Project two streamflow curves for the fictional Ravenglass Basin, plotted from the handout table, one labeled historical and one labeled warmer-climate model. Ask students to say, in one sentence, how the shape of the year changed between the two.

Direct instruction (12 min): Explain that snowpack acts like a slow-release reservoir, and that warming does two things: it shifts precipitation from snow toward rain, and it melts the remaining snow earlier. Introduce the albedo feedback, in which bright snow reflects sunlight while bare, darker ground absorbs it, so less snow leads to more local warming, which melts still more snow. Name the Earth systems involved: the cryosphere (snow and ice) and the hydrosphere (rivers and reservoirs).

Guided model reading (13 min): In pairs, students study the model streamflow table on the handout, comparing the historical and warmer-climate columns month by month. Prompt them to circle the month with the highest flow in each column and to compare the late-summer rows.

Independent practice (12 min): Students answer the numbered short-response items on the handout using the table and the class discussion.

Discussion and adaptation (8 min): As a class, list adaptations a utility could use when summer flow falls: expanded storage, stronger conservation, and water reuse or desalination where feasible. As a formative check, ask each student to write one adaptation on an index card with a one-sentence reason; collect and scan for whether the reason connects to the timing shift.

Ravenglass Basin Snowpack Decline: A Warming Water Cycle — Grade 10 Science
Name: ____________________________ Date: ______________

Student Handout

Suppose the fictional Ravenglass utility received model streamflow output for its basin. The table gives average monthly flow in thousand acre-feet for a historical baseline and for a warmer-climate model run. These values are invented for this scenario.

Month Historical flow (thousand acre-feet) Warmer-climate model (thousand acre-feet)
April 20 30
May 35 32
June 30 18
July 15 8
  1. In the warmer-climate model, does the highest monthly flow arrive earlier or later in the year than in the historical baseline? Name the month.
  2. Compare the July flows in the two columns. Which is lower, and what does that mean for late-summer water supply?
  3. Explain the albedo feedback: how does the loss of reflective snow cover lead to further warming?
  4. The basin stores spring runoff in a reservoir. Explain why the earlier spring peak and the higher April flow do not fully make up for the lower summer flow.
  5. Name one adaptation the fictional Ravenglass utility could use to cope with reduced summer supply, and explain how it would help.
  6. Is the change shown in this model an example of human activity modifying an Earth system? Explain using the cryosphere and the hydrosphere.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key
  1. Answer: Earlier, in April. The warmer-climate column peaks in April at 30, while the historical column peaks later in May at 35, showing the runoff shifting earlier in the year.
  2. Answer: The warmer-climate July flow (8) is lower than the historical July flow (15). Less water arrives in mid-summer, exactly when irrigation and household demand tend to be highest, so the basin faces a supply shortfall late in the season.
  3. Answer: Bright snow reflects much of the sunlight that hits it, while bare ground is darker and absorbs more of that energy. When snow cover shrinks, more sunlight is absorbed, the surface warms further, and that added warmth melts still more snow, which is a reinforcing feedback.
  4. Answer: A reservoir can hold only so much water, so a high early-spring flow may overfill it and spill water that cannot be stored for later. When summer flow then drops, there is less inflow to draw on, so the earlier peak does not replace the missing late-season water. Accept answers citing limited storage capacity, spill, or the mismatch between supply timing and demand timing.
  5. Answer: Accept any reasonable adaptation with a sound reason, such as expanding reservoir storage to hold more of the early peak, strengthening conservation to lower summer demand, or adding water reuse or desalination to create a supply that does not depend on snowmelt timing.
  6. Answer: Yes. Human activity that warms the atmosphere reduces the cryosphere (less snowpack) and reshapes the hydrosphere (earlier, lower-summer streamflow). The model links a human-driven atmospheric change to measurable changes in two connected Earth systems.

Differentiation

Support

Pre-highlight the peak month in each column of the table and provide a labeled snow-to-river diagram so students can see the natural-reservoir idea before they interpret the numbers.

Extension

Ask students to describe how the model columns might change further if warming continued another few decades, and to explain which adaptation from the discussion would become most important and why.

ELL supports

Pre-teach "snowpack," "runoff," "albedo," and "feedback" with simple labeled images in English and, where possible, students' home languages. Provide sentence frames such as "The peak flow moves to ___ because ___" for the short-response items.