Geography Exam 3

fluvial geomorphology

a sub-discipline of geomorphology that investigates how flowing water shapes and modifies earth’s surface through erosion and deposition

what are the two processes linked with fluvial geomorphology

hillslope process and channel process

what are the key geomorphic processes?

1. erosion
2. transportation
3. deposition

what is erosion

it is the removal of weathered rock and soil particles

what is transportation

it is the movement of eroded materials from place to place

what is deposition

it is the laying down of eroded materials

hydrolic cycle

the movement of water in its various forms from place to place

key processes in the hydrolic cycle are

condensation and precipitation

condensation and precipitation are what kind of processes

processes that remove water vapor from the atmosphere

condensation

conversion of water vapor to liquid water as it cools

precipitation

the movement of condensed liquid or solid water from the atmosphere to solid surfaces

evaporation and transpiration are what kind of processes

processes that move liquid into the atmosphere

evaporation

conversion of liquid water to water vapor as it absorbs energy

transpiration

release of water vapor from the leaves and stems of plants

what is the evaporation + transpiration called

evapotranspiration or ET

surface water hydrology

the sub-field of hydrology concerned rainfall and runoff, the routes that surface water takes (across the surface or through rovers or lakes), and the occurrence of floods and droughts

drainage basin

an area of land where precipitation collects and drains to a common outlet

what is another word for a drainage basin

watershed

what happens when precipitation hits the ground

it either infiltrates or runs off

infiltration

soaks into the soil

runoff

flows over the surface into streams and rivers

what is infiltration rate

a measure of how fast water enters the soil, typically expressed in inches per hour

what are some factors that control infiltration

surface permeability, rainfall characteristics and antecedent moisture

surface permeability

soil texture and structure, presence of impervious surfaces

impervious surface

a surface which cannot be penetrated by water

permeable surfaces have what

high infiltration capacities and low runoff

impermeable surfaces have what

low infiltration capacities and high runoff

rainfall characteristics and antecedent moisture

rate of rainfall and amount of water already in storage

sheet flow

water flowing over the hillslope first moves a thin, non concentrated sheet

what is another word for sheet flow

overland flow

rills

sheet flow can then be funneled into tiny erosional depressions

gully

rills can converge to form gullies which are wider, deeper, erosional channels

is a rill or gully wider

gullies are wider and deeper

what are gullies usually

they are dry

what are the two phase processes in hillslope erosion

detachment and transport

what is the first phase process in hillslope erosion

detachment of individual particles

what is the second phase process in hillslope erosion

transport of particles by erosive agents

what eventually happens to particles in the hillslope erosion process

they are deposited, either downslope or into water

erosive energy comes from what

kinetic energy of moving water

raindrop impact

the kinetic energy of a falling raindrop as it impacts the soil surface facilitates detachment

kinetic energy of moving water as it does what

flows over the soil surface

sheet erosion

erosion associated with overland flow that removes loose soil and weathered material

rill and gully erosion

erosion of surface materials as sheet flow is concentrated in hillslope rills and gullies

precipitation and intensity and amount

greater intensity and amount lead to more detachment and transportation

topography

longer and steeper slopes lead to more kinetic energy and erosion

soil characteristics

structure and texture influence the ability of the soil to absorb water and its physical resistance to erosion

vegetation and land use practices

effects of plant cover in rainfall and runoff

river channel

depressions with defined boundaries within which water flows

what is another word for a boundary

bank

river discharge

the volume of water flowing past a given point in a given period of time

what is the river discharge calculation

q = a times v

a in the river discharge calculation is what

channel area

v in the river discharge calculation is what

velocity

discharge is a function of what

velocity and channel area

in a rectangular channel, the calculation would be

q = (w times d) times v

what is w in the river discharge calculation

width

channel depth and width, as well as current velocity, can be measured using a range of what

manual techniques

what is becoming more common

automated systems

are automated systems cheap or expensive

expensive

what does ADCP stand for

acoustic doppler current profiler

stage

the height of a river above a locally defined elevation

staff gages

simple ruled markers on which stage is read manually

automated gages

water level is tracked using an electric sensing system

factors affecting discharge are

weather and climate, rock and soil type, and vegetation cover/land use, topography, drainage basin characterstics

heavy continual rain or melting snow affects what

time for infiltration

what is antecedent rainfall

rain that has already happened, potentially saturating the soil

do permeable rocks and soil absorb what easily or not

they absorb them easily

permeable rocks and soil absorbing water easily causes what

slowing of runoff and discharge

impermeable rocks and soil do what

limit infiltration

what does impermeable rocks and soils limiting infiltration do

causes the water to reach the rivers more quickly

plant cover reduces what

amount and speed of runoff

plant cover reduces amount and speed of runoff by

intercepting incoming rainfall and slowing runoff, which enhances infiltration

steep slopes gives runoff what

less time to infiltrate

characteristics of more gentle slopes

overland flow is slower and infiltration is more likely

erosion by streams

hydraulic action, abrasion/corrasion, solution/corrosion

hydraulic action

erosion of river banks and bed by flowing water

abrasion/corrasion

wearing away of river banks and bed by materials carried in the river flow

solution/corrosion

chemical weathering and erosion by water in the stream

dissolved load

carried in solution

suspended load

solid materials carried within the water flow

bedload

coarser material carried along or near the river bed by saltation and traction

streams deposit material where

they are forced to slow down

what is groundwater

water present beneath the earth’s surface in rock and soil pore spaces and in the fractures of rock formations

what does groundwater do

fills the spaces between soil particles and fractured rock beneath the earth’s surface

zone of aeration

water does not occupy all spaces in the soil and rock

zone of saturation

water occupies all spaces in the soil and rock

what is water budget

the relationship between water input and output at a location over the course of a year

depth to the water table is influences by the rate of

water withdrawal and water recharge

what is water withdrawal

losses

what is water recharge

additions

when withdrawal is greater than recharge what happens

water table drops

when recharge is greater than withdrawal what happens

water table rises

True or False: Just because the soil is saturated in a place, it doesn’t mean the water table is changing

True

capillary soil water is

held in the soil by surface tension

capillary soil water is held in the soil by surface tension and will do what

may return to atmosphere through ET

where does groundwater reemerge at the surface?

places where the land surface drops below the water table, which can help to support rivers, lakes, and springs

what is another place that groundwater reemerges at the surface

wells

what is a well

places where people dig or drill below the water table to remove water

aquifer

a layer of porous rock or material that both stores and transmits water