Water systems, oceans, glaciers & water quality
Water distribution & availability on Earth
Evaporation, condensation, precipitation & flow
Drainage basins, gradient, erosion & deltas
Aquifers, water table, porosity & contamination
Layers, currents, waves & tides
Salinity, pH, dissolved O₂, zones & life
Sources, testing & treatment
Wetlands, estuaries, ecosystem services & threats
Climate change, systems thinking & water sustainability
