Section N: Fluvial Systems and Landforms

where is water stored

in reservoirs (lakes, groundwater)

what are the main paths precipitation can take in the hydrological cycle

• interception (throughfall/stem flow)

• evapotranspiration

• infiltration

  • percolation

  • storage

  • subsurface flow

• runoff/overland flow

• groundwater flow

what is throughfall

water that drips from plant leaves to the ground

what is stem flow

water flowing down plant stems

what is infiltration

the process by which water enters the soil from the surface

what is percolation

the downward movement of water through soil and porous rock layers

what is subsurface flow

movement of water beneath earth’s surface (but above the water table in the unsaturated zone)

what is runoff/overland flow

when precipitation exceeds infiltration capacity causing excess water to flow across land surfaces

what is groundwater flow

the movement of water below the water table in the saturated zone

where is groundwater found

in spaces between particles of rock or soil, cracks in rock

what is the soil water belt

uppermost layer of soil where precipitation is absorbed and stored before moving downward

what are the three types of water in the soil water belt

hygroscopic water, capillary water, gravitational water

what is the unsaturated zone

lies below the soil water belt but above the water table. it contains air and water

what is the water table

the boundary between the unsaturated and saturated zones. it rises and falls depending on precipitation and groundwater withdrawal

what is the saturated zone

the layer where all soil and rock pores are completely filled with water. this is where groundwater is stored

what is an aquifer

a saturated zone that is sufficiently large to be a source of water for people

what is a perched water table

a localized saturated zone (aquifer) that sits above impermeable rock or sediment (aquiclude)

what is an aquiclude

an impermeable layer of rock or sediment that prevents water from passing through.

what does fluvial mean

fluvial comes from fluvius meaning river

why is flowing water important in shaping earth’s surface

flowing water is the most important sculptor of earth’s surface because it erodes, transports, and deposits sediments, creating various landforms

what are degradational landforms

shaped by erosion as water removes rock and sediment. ex: grand canyon (carved by the colorado river)

what are aggradational landforms

created by deposition when rivers drop sediment. ex: nile delta (formed by sediment buildup at the river’s mouth)

what happens to water that can no longer infiltrate into the ground

it becomes overland flow, moving across the surface towards streams and rivers

when does overland flow occur

1. when precipitation rate > infiltration rate (rainfall is too intense for the ground to absorb)

2. ground is saturated (soil cannot hold any more water)

what is baseflow

the portion of streamflow that comes from groundwater seepage into a river or stream, sustaining flow during dry periods

what is streamflow

refers to water moving within a channelized body of water (stream or river), flowing downslope under gravity

what is a rill

a small, shallow channel formed by erosion from overland flows

how is river/stream flow classified

it’s classified based on flow frequency into three types:

1. perennial

2. ephemeral

3. intermittent

what is a perennial stream

flows all year around because it’s continuously fed by groundwater, precipitation or melting snow

what is an ephemeral stream

usually dry and only carries water during and immediately after rainfall

what is an intermittent stream

flows for part of the year, typically when the water table is high enough to provide water