2027 focus
Earth’s fresh waters — hydrology, watersheds, surface water and groundwater.
Study plan
Setup (team of 2, ~50 min, Class II calculator, binder of any size — keep pages in binder at stations)
- Tab the binder by competition sections a–k; include map skills, hydrograph examples, and formula cards.
- Hydrologic cycle & critical zone: fluxes (precip, ET, infiltration, runoff, condensation), reservoirs, residence times, water budgets.
- Climatic controls: rainfall/snowfall seasonality and intensity; orographic lift/rain shadow, continentality, lake effect, elevation; arid–humid spectrum (perennial vs ephemeral, playas, evaporites).
- Drainage basins: watersheds/divides, stream order/networks, drainage patterns/density/texture.
- Fluvial sediment & channel form: braided/meandering/straight/anastomosing + sinuosity; grain properties; bed/suspended/dissolved load; competence/capacity; ripples/dunes/antidunes/bars.
- Fluvial geomorphology: longitudinal profile, gradient, base level, graded streams; knickpoints/waterfalls/v-valleys; capture, downcutting, abrasion, hydraulic action; point bars, cut banks, oxbows, levees, deltas, fans.
- Streamflow & floods: regimes, discharge/velocity/load, open-channel relationships, flood frequency/recurrence.
- Groundwater & karst: aeration/saturation/water table; confined/unconfined/artesian; porosity/permeability; hydraulic gradient; recharge/discharge; saltwater intrusion; sinkholes, caves, springs, disappearing streams.
- Lakes/wetlands (formation types, budgets, stratification/turnover, shorelines; bogs/marshes/swamps/fens) plus paleohydrology structures and human impacts (land use, dams/levees/wells, pollution).
- Measuring/monitoring: topo maps, water-table contours/flow lines, gauging/hydrographs (baseflow vs stormflow, lag), tracers/remote sensing. Weekly timed stations.
Tips
Always identify upstream vs downstream on map questions before answering.