Studied by 43 people
Population Water resources Surface water Ground water
are population sizes similar among countries and continents
no
how do population distributions change over age groups
starts small, increases, then slowly decreases
carrying capacity
population size environment can sustain
logistic growth! “S” shape curve
linear population curve
constant slope
exponential population curve
increasing slope
geometric growth rate
increases in the size of the population depend on the population size
calculated using the 'compound interest formula'
linear growth rate
adding the same amount in each unit of time
y = mx + b
total fertility rate
average number of children a woman has over lifetime
replacement fertility rate
maintain a steady population size (zero growth)
ecological footprint
resources a person uses, can be considered as an area of land needed to produce these resources
how do humans alter the carrying capacity
migration, agriculture, medical advances, and communication
what is the current global population
8.1 billion people
projected carrying capacity of the Earth for humans
maybe 2, 9-10, 40, years no fixed number
what reservoirs contain the most fresh water
glacier ice !!
what reservoirs contain the most salt water
ocean
ocean residence time
3,200 years
glacier residence time
20 - 100 years
soil moisture shallow residence time
1 - 2 months
deep groundwater residence time
100 - 200 years
deepest groundwater residence time
10,000 years
lake residence time
50 - 100 years
river residence time
2 - 6 months
atmosphere residence time
9 days
river “off stream” uses
drinking water
river “on stream” uses
navigation through waterways
recreational boating and swimming
hydropower production
water balance equation
amount of precipitation compared to the water leaving the system as runoff or as evapotranspiration
mass of inflow - mass of outflow = change in stored mass
what/who is the biggest water user in the us
Thermoelectric power plants and irrigation
California
where does the largest portion of rainwater that falls on a drainage basin go
streams and rivers
what is a drainage basin
an area of land where water from rain or snow melt drains downhill into a body of water such as a river, lake, wetland or ocean
water budget
what is a drainage divide
water flowing on one side of a divide empties into one body of water, while water flowing on the other side empties into another
what direction does surface-water flow on a topographic map
downhill perpendicular to the contour lines
how do urban area’s impact recharge the subsurface
urbanization creates new pathways and sources of water for recharge, including leaking water pipes, sewers, septic tanks and irrigation
what are the advantages and disadvantages of the different sources of drinking water
groundwater well - close to user, filtered by geologic media, lower pumping rates, need recharge of water
surface water - requires distribution, exposed to surface contamination, soft, high pumping rates, low residence time
treated sea water - needs energy, expensive, generates wastewater
treated waste water
captured rain water
what factors impact runoff and infiltration(the velocity or speed at which water enters into the soil) rate
relief/topography
soil or rock type
vegetation
surface detention - portion of the storm rainfall that flows on the land surface toward the channel, but has not yet reached it
storm intensity
laminar water flow
smooth parallel flow, no energy lost
turbulent water flow
chaotic flow, contains eddies(circular currents of water) that consume energy
hydrograph
discharge vs. time
identifies different hydrologic processes
recurrence interval
average time between events equal or greater than a discharge rate
based on rank of peak annual discharge rates
effects of urbanization on runoff and infiltration
less water infiltrates and more and more runs off
baseflow in channel of basin
water from long term (slow) sources - ground water, ponds, wetlands
storm-flow in channel of a basin
water to stream from a rain event
braided stream
contain intertwined channels flowing around sand and gravel bars
steep slope
high energy
high competence (carry large particles)
large width
meandering stream
curving path, erosion along outside bends, deposition on inside bends
lower energy
lower slope
low competence (carry small particles)
high capacity
form oxbow lakes, erosion causes river to break at the bend, making C shaped lakes
reasons for creating dams / consequences
(+) flood control
(+) energy production
(+) drinking water source
(-) restricts navigation and migration of organisms
(-) sediment movement is impeded
(-) increased erosion downstream
how do meandering streams evolve over time
erosion on the outside bend and deposition on the inside bend of a river, making C shaped lakes ‘oxbow lake’
how is river discharge determined
volume of water per time
measured using flow meter or engineered structure
stream competence vs capacity
stream competence - size of material stream can transport
stream capacity - mass of material a stream carries
bed load vs suspended load
bed load - sediment ‘pushed’ along bed of stream
suspended load - sediment that is carried by water
alluvium
sediment stream transports and deposits (clay, sand, silt)
levee
raised river banks
form naturally, sediments deposited along banks during flooding
humans create/enlarge to protect flood plain
increases downstream flooding
traps water drain if overtapped
flood plain
an area of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding
terrace
steep walls leading higher out of the valley
what is the purpose of retention ponds (ponds or pools designed with additional storage capacity)
to trap runoff from parking lots and roof tops to reduce peak flows in nearby streams
aquifer
capable of yielding significant/economic quantities of water
unconfined aquifer - above is water table
confined aquifer - above is aquitard
aquitard (confining unit)
impedes groundwater flow, horizontal layer between confined and unconfined aquifer
hydraulic head and its components
the elevation of water in a tube open to the atmosphere
three components - pressure, elevation, and velocity head
measure of energy
not needed in slow groundwater velocities
what direction does groundwater flow
toward hydraulic heads
toward pumping wells
towards gaining stream (‘V’ angle)
away from losing stream (‘V’ angle)
how does a pumping well impact groundwater levels
produces a cone of depression
water levels lowered
altered aquifers may never fully recover
terms used to describe the different subsurface hydrolic zone and geologic units
water table
unconfined aquifer
aquitard
confined aquifer
Darcy’s law
an equation that describes the flow of a fluid through a porous medium
Q = -K x A h/l
Q = total discharge
K = hydraulic conductivity
H = hydraulic head
L = distance in direction of flow
spring water (FDA criteria)
water derived from an underground formation from which water flows naturally to surface of the earth
different classes of subsurface water
meteoric - infiltrated from precipitation
connate - water trapped in sediments during deposition
juvenile - ‘new’ water, from interior of earth
magmatic - cycled through igneous rocks
are groundwater and surface water related
yes!!!!!!!!!!!!!
what is the amount of pore space in a material called
POROSITY
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