Hydrology and Fluvial Processes Vocabulary

Flashcards of key vocabulary and definitions related to hydrology, fluvial processes, and drainage basins.

Precipitation

All forms of water falling from the atmosphere, such as rain, snow, hail, or dew.

Inputs

The total water entering the drainage basin system from precipitation or artificial sources.

Irrigation

Artificial application of water to land, usually for agriculture.

Interception

Water held temporarily on plant surfaces before reaching the ground.

Throughfall

Water that drips from vegetation or falls through gaps to the soil.

Stemflow

Water that flows down stems or trunks of plants to the ground.

Transpiration

Water vapor released from plant leaves into the atmosphere.

Vegetation

Plants that intercept, store, and transpire water in the drainage basin.

Infiltration

The process of water soaking into the soil from the surface.

Soil Moisture

Water stored in soil pores, available to plants.

Field Capacity

The maximum amount of water soil can hold after excess has drained.

Wilting Point

The soil moisture level below which plants can no longer extract water.

Percolation

Downward movement of water from soil to rock layers below.

Recharge

The replenishment of groundwater through infiltration or seepage.

Aquifers

Rock layers that store and slowly transmit groundwater.

Water Table

The upper surface of the saturated zone of groundwater.

Phreatic Zone

The permanently saturated layer beneath the water table.

Aeration Zone

The unsaturated zone above the water table.

Aquiclude

An impermeable rock layer that prevents water flow.

Aquitard

A rock layer with low permeability that slows water movement.

Groundwater

Water stored underground in soil or rock layers.

Hydrological Cycle

The continuous movement of water between land, sea, and atmosphere.

Drainage Basin

The area of land drained by a river and its tributaries.

Watershed

The boundary separating adjacent drainage basins, usually high ground.

Open System

A system that allows energy and matter (like water) to enter and exit.

Storm Hydrograph

A graph showing river discharge before, during, and after rainfall.

Cryosphere

Earth’s frozen water environments, such as glaciers and snowfields.

Endorheic Basin

A closed drainage basin that doesn’t drain to the sea but ends in inland lakes or depressions.

Overland Flow

Water flowing over the land when infiltration is exceeded.

Throughflow

Lateral water movement through the soil, often downslope.

Base Flow

Groundwater seepage that sustains streamflow during dry periods.

Streamflow

The flow of water in a river or stream channel.

River Discharge

The volume of water flowing through a river cross-section per second.

Velocity

The speed at which water flows through a river.

Hydraulic Radius

A measure of flow efficiency (cross-sectional area ÷ wetted perimeter).

Turbulent Flow

Chaotic, swirling water that can carry sediment.

Laminar Flow

Smooth, parallel flow of water in layers.

Evaporation

The process by which water changes from liquid to vapor.

Evapotranspiration

Combined water loss from evaporation and transpiration.

Potential Evapotranspiration

The amount of water that would evaporate if unlimited water was available.

Outputs

Water that exits the drainage basin, mainly through runoff or evapotranspiration.

Erosion

The wearing away of land by flowing water.

Abrasion

Erosion caused by river load scraping against the bed and banks.

Attrition

Rocks and sediments collide and break into smaller, rounder pieces.

Hydraulic Action

Erosion caused by the force of moving water on banks and bed.

Cavitation

Erosion from the explosion of air bubbles in fast-flowing water.

Solution (Corrosion)

Chemical erosion where water dissolves minerals from rock.

Load

The material a river carries, including sediment and dissolved substances.

Suspension

Fine particles like silt carried within the water.

Saltation

Medium particles bouncing along the riverbed.

Traction

Large particles rolling or sliding along the riverbed.

Solution (Transport)

Minerals dissolved in water and carried invisibly.

Floatation

Organic materials like leaves floating on the surface.

Capacity

The maximum load a river can carry at a given time.

Competence

The largest particle size a river can transport.

Hjulström Curve

A graph showing the velocity needed for erosion, transport, and deposition.

Critical Erosion Velocity

The minimum velocity needed to move a specific particle size.

Deposition

The laying down of sediment when energy or velocity decreases.

Settling Velocity

The speed at which particles fall out of the water column.

Flocculation

Clumping of fine particles in saltwater, making them settle faster.

Waterfall

A sudden vertical drop in a river, formed by differential erosion.

Meander

A natural bend in a river formed by erosion and deposition.

Oxbow Lake

A U-shaped lake formed when a meander is cut off from the river.

Floodplain

Flat land next to rivers formed by sediment deposition during floods.

Levees

Raised riverbanks formed by coarse sediment deposited during floods.

Delta

A landform created by sediment deposition at a river’s mouth.

Top-set Beds

Coarse sediment deposited at the top of a delta.

Fore-set Beds

Medium-grained sediment deposited outward in a delta.

Bottom-set Beds

Fine sediment deposited furthest out in a delta.

Bioconstruction

Vegetation’s role in stabilizing and building landforms like deltas.