2027 focus
Earth’s fresh waters — hydrology, watersheds, surface water and groundwater.
Study plan
- Map the water cycle with stocks and fluxes (evaporation, infiltration, runoff, recharge).
- Learn stream features, drainage patterns, and floodplain vocabulary.
- Practice reading hydrographs and topographic/watershed maps.
- Review freshwater human impacts: dams, withdrawals, pollution.
Tips
Always identify upstream vs downstream on map questions before answering.