Water and Carbon Cycles: Systems, Processes, and Changes

Vocabulary practice flashcards covering systems, the local and global water cycle, flood hydrographs, carbon cycle stores and transfers, the enhanced greenhouse effect, feedback loops, and land use changes.

Open System

A system that receives inputs and transfers outputs of energy or matter with other systems.

Closed System

A system where energy inputs equal outputs and no matter enters or leaves the system.

Dynamic Equilibrium

A state in a system where inputs equal outputs despite changing conditions.

Positive Feedback

A cyclical process in which a chain of events amplifies or heightens the impacts of the original event.

Negative Feedback

A cyclical process in which a chain of events nullifies or counteracts the impacts of the original event, leading back to dynamic equilibrium.

Drainage Basin System

A subsystem of the hydrological cycle operating at a local scale, acting as an open system with inputs (precipitation), outputs (evapotranspiration, runoff), stores, and flows.

Precipitation

Any water that falls to the surface of the Earth from the atmosphere, including rain, snow, and hail.

Convectional Rainfall

Rainfall caused when warm air heated by the sun rises, cools, and condenses at higher altitudes.

Relief Rainfall

Rainfall caused when warm, moist air is forced upward by a physical barrier such as a mountain range, condensing at higher altitudes.

Frontal Rainfall

Rainfall that forms when two air masses of different temperatures meet, forcing the lighter, less dense warm air to rise over the cool air and condense.

Evapotranspiration

The total moisture output from a drainage basin to the atmosphere, comprising evaporation from surfaces and transpiration from plant leaves.

Infiltration Capacity

The maximum rate at which water can move from the ground surface into the soil.

Percolation

The slow downward movement of water from the ground or soil into porous rock or rock fractures.

Throughflow

The lateral movement of water through the soil and into streams or rivers.

Surface Runoff (Overland Flow)

Water flowing above the ground surface either as sheetflow across a wide area or channelled in small rills.

Groundwater Flow

The slow transfer of water through permeable rock strata below the water table.

Stemflow

The flow of intercepted water down plant stems, leaves, branches, or tree trunks to reach the ground.

Water Table

The upper surface level underground at which pore spaces and fractures in soil and rock become fully saturated with water.

Water Balance

The expression of water storage and transfer in a drainage basin system, calculated using the formula: $\text{Precipitation} = \text{Total Runoff} + \text{Evapotranspiration} \pm \Delta\text{Storage}$.

Field Capacity

The maximum possible level of water storage that a given soil can hold before it is saturated and excess water causes runoff or flooding.

Soil Water Budget

The annual balance between precipitation inputs and evapotranspiration outputs, determining seasonal changes in soil moisture storage.

Aquifer

A permeable underground rock store that holds and transmits groundwater.

Inter-Tropical Convergence Zone (ITCZ)

A low-pressure zone located along the equator where converging trade winds generate rising air, high convectional rainfall, and monsoons.

Cryosphere

The portion of the Earth's system consisting of frozen water, including glaciers, ice caps, ice sheets, snow cover, and permafrost.

Flood Hydrograph

A graph plotting precipitation against river discharge over time to illustrate a drainage basin's hydrological response to a rainfall event.

Discharge

The volume of water passing through a river's cross-sectional point at a given time, measured in cubic metres per second ($\text{cumecs}$).

Lag Time

The time interval between peak rainfall and peak river discharge on a flood hydrograph.

Baseflow

The normal, steady day-to-day discharge of a river supplied by slow groundwater seepage.

Bankfull Discharge

The maximum volume of water a river channel can hold without overflowing its banks.

Flashy Hydrograph

A hydrograph characterised by a short lag time, a steep rising and falling limb, and a high peak discharge.

Subdued Hydrograph

A hydrograph with a long lag time, a gently sloping rising and falling limb, and a low peak discharge.

Antecedent Rainfall

Rainfall that occurs prior to a main storm event, saturating the ground and filling soil storage capacity.

Carbon Sequestration

The transfer and capture of carbon dioxide from the atmosphere into other long-term or short-term stores, via natural or artificial means.

Carbon Capture and Storage (CCS)

An artificial mitigation technology where $CO_2$ emissions from industrial processes or power stations are captured and piped into underground geological formations.

Carbonation Weathering

A chemical weathering process where atmospheric carbon dioxide dissolves in rainwater to create weak carbonic acid that dissolves carbonate rocks like limestone.

Sere

A complete sequence of developmental stages in a vegetation succession as a plant community evolves towards its climatic climax.

Climatic Climax

The final, stable stage of a vegetation succession that exists in dynamic equilibrium with the prevailing regional climate.

Lithosere

A primary plant succession that begins on an environment of bare rock.

Carbon Sink

Any store or reservoir that absorbs and accumulates more carbon than it releases.

Carbon Source

Any store or reservoir that releases more carbon into the atmosphere than it absorbs.

Carbon Flux

The rate of transfer or flow of carbon between different global stores over time.

Carbon Budget

The balance between carbon inputs and outputs to a specific store, or the balance of exchanges between the four major global spheres.

Net Primary Productivity (NPP)

The net amount of carbon absorbed and retained as biomass by green plants per unit area over a given period.

Enhanced Greenhouse Effect

The intensification of the natural greenhouse effect resulting from anthropogenic greenhouse gas emissions, causing global temperatures to rise.

Radiative Forcing

The difference between incoming solar radiation absorbed by Earth and the thermal energy radiated back into space.

Milankovitch Cycles

Cyclical variations in the Earth's orbit, tilt, and wobble that alter the amount and distribution of solar radiation reaching the planet over geological time scales.

Permafrost

Ground, soil, or rock that remains at or below $0\,^\circ\text{C}$ for at least two consecutive years.

Carbon Fertilisation

The enhanced rate of photosynthesis and growth in plants triggered by elevated atmospheric carbon dioxide concentrations.

Peatland (Moorland)

A wetland landscape comprising waterlogged, acidic soil and peat (partially decayed organic matter), representing the largest terrestrial carbon store.