Chapter 9 Running Water and Groundwater

infiltration

the process by which water on the ground surface enters the soil

runoff

water that flows over the land surface and doesn’t infiltrate, eventually making its way to streams, rivers, lakes, and oceans

transpiration

the process by which plants release water vapor into the atmosphere through their leaves

Drainage Basin (watershed)

an area of land where all water that falls on it drains to a common point, such as a river, lake, or ocean. It’s defined by the topography

Divide

the high-elevation ridge that separates one drainage basin from another. Water on either side of a divide flows to different flows to different drainage basins

Headward Erosion

erosion that occurs at the upstream end of a stream or river channel, causing it to lengthen over time

Radial Pattern

a drainage pattern where streams flow outward from a central high point, such as a volcano or dome

Rectangular Pattern

a drainage pattern characterized by a network of streams with right angle, often developing in areas with jointed or fractured rock

Trellis Pattern

a drainage pattern where streams flow through valleys between ridges, with smaller tributaries joining at right angles, resembling a trellis or ladder

Discharge

the volume of water flowing past a given point in a stream or river per unit of time

Longitudinal Profile

a graph showing the change in elevation of a stream channel from its headwaters to its mouth. It generally shows a concave-upward shape

Pothole

bowl-shaped depressions eroded into the bedrock of a stream channel by the abrasive action of sediment carried by the water

Dissolved Load

the material carried by a stream in solution, such as salts and minerals

Suspended Load

fine sediment particles (clay, silt, fine sand) that are carried within the water column of a stream

Bed Load

larger sediment particles (gravel, pebbles, cobbles) that are transported along the bottom of a stream by rolling, sliding, or bouncing (salutation).

Setting Velocity

the speed at which sediment particle falls through a fluid. Larger and denser particles have higher settling velocities

Saltation

the process by which particles are transported by a stream by bouncing along the bed

Capacity

the maximum amount of sediment a stream can carry

Competence

the largest size of sediment particle a stream can transport

Sorting

the process by which a stream separates sediment particles based on their size, shape, and density. Faster-moving water tends to carry finer sediments further

Alluvium

sediment deposited by a stream or river

Meander

a bend or curve in a river channel

Cut Bank

the outer bank of a meander, where erosion occurs due to faster water flow

Point Bar

a deposit of sediment on the inside of a meander bend, where water velocity is slower

Oxbow Lake

a crescent-shaped lake formed when a meander cutoff occurs

Braided Canal

a stream channel that is divided into multiple, interconnected channels separated by bars and islands, This often occurs in areas with high sediment loads and variable discharge

Stream Valley

the area surrounding a stream channel, including the valley floor and the valley walls

Floodplain

a flat area adjacent to a river channel that is subject to flooding

Incised Meander

a meander that has been cut down into the bedrock die to uplift or lowering of base level

Stream Terrace

a flat, elevated surface alongside a stream valley, representing a former floodplain level. They are evidence of past changes in base level or stream activity

Natural Levee

an elevated ridge of sediment deposited along the banks of a river during floods

Back Swamp

a low-lying area behind natural levees, often poorly drained

Yazoo Tributary

a tributary that flows parallel to the main river along the edge of the floodplain before eventually joining it

Alluvial Fan

a fan-shaped deposit of sediment formed where a stream flows out of a steep mountain canyon onto a flatter plain

Zone of Saturation

the subsurface zone where all pore spaces are filled with water

Water Table

the upper surface of the zone of saturation

Unsaturated Zone

the subsurface zone above the water table where pore spaces contain both air and water

Porosity

the percentage of material’s volume that is made up of pore spaces

Permeability

the ability of a material to transmit fluids, It depends on the size and interconnectedness of the pore spaces

Aquitard

a layer of impermeable material that restricts the flow of groundwater

Aquifer

a layer of permeable rock or sediment that can store and transmit groundwater

Well

a hole dug or drilled into the ground to access groundwater

Drawdown

the lowering of the water table around a pumping well

Artesian System

a groundwater system where water is confined under pressure, allowing it to rise to the surface naturally through a well

Confined Aquifer

an aquifer that is bounded above and below by aquitards

Spring

a natural discharge of groundwater to the surface

Perched Water Table

a localized water table that sits above the main water table due to an impermeable layer

Hot Spring

a spring that discharges water that is significantly warmer than the surrounding groundwater

Geyser

a hot spring that periodically erupts steam and hot water

Cavern

a large underground chamber, often formed by the dissolution of limestone by groundwater

Stalactite

a speleothem (cave formation) that hangs from the ceiling of a cavern

Stalagmite

a speleothem that grows upward from the floor of a cavern

Karst Topography

a landscape characterized by caves, sinkholes, and underground drainage, formed by the dissolution of soluble rocks like limestone

Sinkhole(sink)

a depression in the ground surface caused by the collapse of a cave roof or by the dissolution of underlying limestone