Hydrological Cycle

Vocabulary flashcards covering the hydrological cycle, global water distribution, pathways of moisture, and hydrological processes based on lecture notes.

Hydrological Cycle (Water Cycle)

A closed system in which water is continuously moved from the world's oceans, through the atmosphere, falls to earth as rain, and travels back to the ocean in an endless loop via flows and stores.

Closed System

A self-contained system—such as the hydrological cycle—where water is recycled continuously between the oceans, atmosphere, and land without net gain or loss.

Atmospheric Moisture

The moisture held in the atmosphere at any given time, which on average is sufficient to provide every place on Earth with $2.5\,\text{cm}$ of rain.

Theoretical Global Water Depth

The uniform depth of $3\,\text{km}$ to which water would cover the entire surface of the planet if it were evenly distributed.

Total Global Saltwater (Shiklomanov Estimate)

Accounts for $97.5\%$ of all water on Earth, representing a total volume of $1\,365\,000\,000\,\text{km}^3$.

Total Global Freshwater (Shiklomanov Estimate)

Accounts for $2.5\%$ of all water on Earth, representing a total volume of $35\,000\,000\,\text{km}^3$.

Glaciers and Permanent Snow Cover

The largest reservoir of fresh water, storing $68.9\%$ of Earth's total freshwater supply.

Groundwater (Shiklomanov Classification)

A freshwater store comprising $30.8\%$ of total global freshwater, which includes soil moisture, swamp water, and permafrost.

Lakes and River Storage

Surface freshwater storage accounting for $0.3\%$ of global freshwater (and only $0.009\%$ of total water on Earth).

Solar Energy

The driving force behind the hydrologic cycle that powers the continuous transformation and transfer of water.

Gravity

The physical force that helps keep water moving downward through various stages of the hydrological cycle.

Throughflow

The flow or movement of water laterally through the soil within the hydrological system.

Precipitation

The major moisture input into the hydrologic system, occurring when condensed atmospheric water vapor falls to the Earth's surface.

Convectional Thunderstorms

A form of precipitation characterized by short and heavy rainfall that dominates the weather pattern in Botswana.

Evaporation

Moisture loss into the atmosphere from water surfaces, soil, and vegetation driven by wind and the sun's rays, exceeding $1\,\text{m}$ per year in Botswana and approaching $2\,\text{m}$ in Maun.

Transpiration

A biological process by which moisture is lost directly from a plant through the minute pores in its leaves.

Interception

The capture and temporary storage of precipitation by vegetation surfaces before it reaches the ground.

Stem Flow

The movement of intercepted precipitation draining down the stems, branches, and trunks of plants and trees to the soil.

Through Fall

Precipitation that drops directly through gaps in the plant canopy or drips from leaves and branches down to the ground surface.

Infiltration

The process by which water on the ground surface soaks down into the soil.

Percolation

The downward movement of infiltrated water through deeper soil layers and permeable rock strata toward the water table.

Zone of Aeration

The subsurface layer above the water table where pore spaces contain both air and water.

Water Table

The upper boundary dividing the unsaturated zone of aeration from the underlying zone of saturation.

Zone of Saturation

The subsurface region below the water table where all pore spaces and rock fractures are completely saturated with water.

Tyson (1986) Rainfall Analysis

A historical dataset and graph recording the percentage deviation of rainfall from the mean between 1910 and 2000.