Baseline concentration of annual precipitation% change in water entering aquifers% change in surface water used for irrigation% change in groundwater...
GMAT Information and Ideas : (Ideas) Questions
| Baseline concentration of annual precipitation | % change in water entering aquifers | % change in surface water used for irrigation | % change in groundwater used for irrigation |
|---|---|---|---|
| Precipitation is currently somewhat concentrated | 4.9 | 0.4 | 0.9 |
| Precipitation is currently evenly distributed | 11.0 | 9.0 | 7.9 |
Some climate models for the western United States predict that while total annual precipitation may remain unchanged from the present level, precipitation will become concentrated into fewer but more intense rain and snow events. University of Texas climate scientist Geeta Persad and her colleagues simulated how the amount of water entering aquifers and the amount being used for irrigation purposes would change if this were to occur. Persad and her colleagues concluded that concentration of precipitation into fewer events would result in a higher number of dry days, triggering more irrigation, but that this change in irrigation output is highly sensitive to the baseline concentration of precipitation that currently exists in an area.
Which choice best describes data from the table that support Persad and her colleagues' conclusion?
If baseline precipitation is somewhat concentrated, the amount of water being used for irrigation will increase 0.4% for surface water and 0.9% for groundwater, whereas the amount of water entering aquifers will increase 11.0% if baseline precipitation is evenly distributed.
If baseline precipitation is somewhat concentrated, water use for irrigation will increase only slightly, whereas it will increase 9.0% for surface water and 7.9% for groundwater if baseline precipitation is evenly distributed.
If baseline precipitation is somewhat concentrated, the amount of water entering aquifers will increase 4.9%, while the amount being used for irrigation will increase 0.4% for surface water and 0.9% for groundwater.
If baseline precipitation is somewhat concentrated, water use for irrigation will decline by a small amount, whereas it will increase 11.0% for surface water and 9.0% for groundwater if baseline precipitation is evenly distributed.
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "Some climate models for the western United States predict that while total annual precipitation may remain unchanged from the present level, precipitation will become concentrated into fewer but more intense rain and snow events." |
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| "University of Texas climate scientist Geeta Persad and her colleagues simulated how the amount of water entering aquifers and the amount being used for irrigation purposes would change if this were to occur." |
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| "Persad and her colleagues concluded that concentration of precipitation into fewer events would result in a higher number of dry days, triggering more irrigation, but that this change in irrigation output is highly sensitive to the baseline concentration of precipitation that currently exists in an area." |
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Provide Passage Architecture & Core Elements
Main Point: Climate research shows that when precipitation becomes more concentrated, the increase in irrigation needs varies dramatically depending on whether an area already has concentrated or evenly distributed precipitation patterns.
Step 2: Interpret the Question Precisely
What's being asked? Which data from the table supports the researchers' conclusion
What type of answer do we need? Specific data that demonstrates their key finding
Any limiting keywords? "best describes data from the table that support" - we need data that directly backs up their conclusion
Step 3: Prethink the Answer
- The researchers concluded that irrigation changes are "highly sensitive to the baseline concentration of precipitation."
- This means we need data showing that areas with different baseline precipitation patterns respond very differently to the same climate change.
- The right answer should highlight the dramatic contrast between the two baseline conditions.
If baseline precipitation is somewhat concentrated, the amount of water being used for irrigation will increase 0.4% for surface water and 0.9% for groundwater, whereas the amount of water entering aquifers will increase 11.0% if baseline precipitation is evenly distributed.
✗ Incorrect
- Mixes up the data and doesn't clearly show the comparison that supports the conclusion about sensitivity
If baseline precipitation is somewhat concentrated, water use for irrigation will increase only slightly, whereas it will increase 9.0% for surface water and 7.9% for groundwater if baseline precipitation is evenly distributed.
✓ Correct
- Shows that somewhat concentrated areas have only slight irrigation increases while evenly distributed areas have much larger increases. This directly demonstrates the "high sensitivity" conclusion by showing how dramatically different the irrigation responses are.
If baseline precipitation is somewhat concentrated, the amount of water entering aquifers will increase 4.9%, while the amount being used for irrigation will increase 0.4% for surface water and 0.9% for groundwater.
✗ Incorrect
- Only describes one baseline condition and doesn't provide the comparison needed to support the conclusion about sensitivity
If baseline precipitation is somewhat concentrated, water use for irrigation will decline by a small amount, whereas it will increase 11.0% for surface water and 9.0% for groundwater if baseline precipitation is evenly distributed.
✗ Incorrect
- Claims irrigation will "decline" for somewhat concentrated areas, but the data shows increases