Rivers and Groundwater Thompson 24-25 HON

aquifer

Any rock or sediment through which groundwater flows easily

cutbank

eroded stream bank on the outside of a meander curve

Delta

a fan-shaped deposit of sediment that forms when a river flows into a non-flowing large body of water, such as a lake, ocean or inland sea.

Deposition

The process of laying down of sediment.

Divide

A ridge of land that separates one drainage basin from another.

Watershed

All of the land area where rainfall will run off or infiltrate into a river system, bounded by divides. Same as a watershed.

Floodplain

a flat plain next to a river that is made of fine river sediment and is subject to periodic flooding

Gradient

the slope of a river channel or landscape over a certain distance. Expressed by the equation: change in elevation/distance

groundwater

water beneath the surface stored and flowing in pore space in rock/sediment.

Meander

a bend in the channel of a river. Characteristic formation when gradient decreases and erosion is mostly side-to-side vs. downcutting.

permeability

The ability of a rock or sediment to let fluids pass through its open spaces, or pores.

Point Bar

crescent shaped pile of sediment built up by river deposition on the inside of a meander

River System

A river and all of its tributaries

Tributary

a smaller river that flows into a bigger river

water table

the top of the zone of saturation

zone of aeration

the zone in an aquifer above the water table where the pore spaces are filled with air

zone of saturation

the zone in the aquifer below the water table where all open spaces are filled with water

mouth

place where a river empties into another body of water

head

a stream's point of origin

Infiltration

Flow of water from the land surface into the subsurface.

porosity

the amount of space between sediments underground

percolation

the movement of water between sediments once the water is underground

aquitard

an impermeable layer

cone of depression

the drawing down of the water table around a well (into a funnel shape)

load

the sediment carried by a river

saltation

a “skipping” motion of sediments up and down near the river bed; happens to smaller sediments

trunk

the main channel of a river

levee

raised river banks, created by deposited sediment during floods or by human intervention

oxbow lake

a U-shaped body of water formed when a meander in a river is cut off from the main channel.

downcutting

the creation of a channel as water cuts down (erodes) through the surface

headward erosion

the process by which a river or stream extends its length upstream by eroding the land at its source.