Water Cycle — Ecological Framework

Ecological Framework

Stores

Oceans, ice and snow, atmosphere, rivers and lakes, soil moisture and groundwater. Each store has a quantity at a time and exchanges water at rates that vary with conditions.

Transfers

Evaporation: liquid to vapour.
Transpiration: plant-mediated water transfer to air.
Sublimation: ice or snow directly to vapour.
Condensation: vapour to liquid droplets.
Precipitation: water returns from the atmosphere.
Runoff: surface movement toward drainage routes.
Infiltration: entry into soil.
Recharge: addition reaching groundwater.

Key distinctions

Evaporation does not require boiling. Visible clouds contain droplets or ice, not only invisible vapour. Infiltration is not automatically recharge because soil storage and plant uptake intervene. Groundwater and surface water can exchange in different directions under different hydraulic conditions.

Balance

Storage change = inflows − outflows for one boundary and period. Keep stocks and flows in compatible units. Do not assign every unexplained residual to one pathway without evidence.

Human influence

Land cover, reservoirs, pumping and irrigation can alter storage, flow timing and partitioning. Pollution changes quality as water moves. Explain the particular pathway affected and qualify the scale of the effect. The cycle is a connected network with different residence times, not one fixed sequence completed uniformly by all water.

Always label the period of a balance: a storm response and a long-term groundwater trend answer different questions.