Describes properties of flow Re _ 2000 = turbulent Ke = 500-2000 = transition from L to T

Exam #1 Flashcards by Maddy Palmer

Drainage density

Reflects spacing of stream channels
D= length of channel (km) / basin area (km2)

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Stream order and 3 methods

Way to describe stream size
Horton, shreve, strahler

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Horton stream order

Looks at entire stream length

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Strahler stream order

Just stream reach

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Shreve stream order

Just stream reach but additive

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Basin magnitude (m)

Of first order streams in a basin

Magnitude=shreve stream order

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Ruggedness Number

Drainage density x relief
Relief = max elev - min elev

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Reynolds’s number

Describes properties of flow
Re <_ 500 = laminar
Re>_ 2000 = turbulent
Ke = 500-2000 = transition from L to T

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Reynolds’s Number equation

Re=vle/u
V=flow velocity
L= length→ a/Pw
e= density of water
u= viscosity of water

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Hydraulic radius

Ratio that describes how efficient water flow is
Rh= A/ pw
A-cross sectional area
Pw- wetted perimeter

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Froude Number

Ratio of water velocity (v) and surface wave propagation velocity (vw)
→ measures how erosive flow is
Fr= v / vw =v/ square root (gh)
V-velocity of water
G-accel of gravity
H-height of water column

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Supercritical

V> vw → fr> 1
Shallower flow, more erosive energy

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Critical flow

V= vw → fr =1
Ripple wave moving upstream would be stationary

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Subcritical flow

V< vw → fr <1
Tranquil, deeper flow.. Little erosive energy

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Q-H relationship for critical flow @dip

Q = WcHcVc
Q → river discharge
Wc →width
Hc →height
Vc → square root ( gh)

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Water flow over a spillway

Q=Wc (square root of 8/27 g)H^ 3/2
Wc = width of water@top of dam
H= height of water just above dam

Q=v2WcH2
V2= velocity@ dip
H2=height of water at dip

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Weirs

Man-made structure designed to force flow to become critical so Q can be calculated

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Two main types of weirs

Rectangular→ flow through rectangular opening
Q = CWcH^ 3/2
V-notch → flow through v, more accurate
Q=ctan(0/2)H^5/2

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Major water reservoirs

→ lakes/streams/river/ponds
→glaciers (ice)
→aquifers:ground water
→ atmosphere
→ soils

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Hydrology

Mainly surface water concerned w/origin, circulation, distribution, properties of water on earth

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Hydrography

Stream discharge (Q) over time

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Infiltration capacity

Rate @ which water can be absorbed into ground
IC>P= No OF
IC<P=OF

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Saturated overland flow

Antecedent moisture
Ground already saturated
Make things flashier

Subsurface storm flow

Moves through uncomplicated upper layer of soil/regolith

Annular

Structural domes + basins

Radial

Volcano, domes

What controls drainage patterns

Variable weathering by bedrock Tectonics Volcanism Fractures, jointing Slopes

Drainage density

Network of progressively larger channels that drain water from an area bounded by drainage divides

Watershed

"Catchment" Area of land where water collects and drains through an outlet

Stage

Height above reference point

Staff gauge

Scale placed in water

Water balance

Way to track movement of water within and between a certain reservoir In= out + s/t

Flowing water

Moving Streams, runoff, rivers

Stagnant water

Lakes, ponds, wetland Storage

Laminar flow

Flow that happens in thin, smooth, parallel layers with no disturbance

Turbulent flow

Velocity and direction of water particles vary erratically at any given point

Runoff/ Horton overland flow

Water flowing over ground surface directly into stream channel Occurs where there is a barrier to infiltration Creates flashy flows

Evapotranspiration

Vegetation uses water through root system Excess water lost by evaporation directly from plant

Interception

Vegetation captures precipitation Never reaches ground Rate of 10-50 % of precip

Conformal

Mix of patterns

Multibasinal

Hummocky Smile-like shapes

Rectangular

Joints @right angles

Trellis

Dipping or folding

Parallel

Moderate to steep slopes

Dendritic

Tree-like

Laser beams

Mounted on bridge or other overhead structure Linked to data recorder

Laser beams

Mounted on bridge or other overhead structure Linked to data recorder

Float recorder

Float dropped into stilling well and level is recorded Analog or digital Water needs to be relatively calm

Pressure transducer

Measures atmospheric pressure just above water level and water pressure below water surface to get depth change May use stilling well

Stilling well

Well directly connected to stream channel Good for measurements because effects of turbulence or flow variations are limited

Float

how long it takes for an object to move down channel at known distance V =(0.65vfloat)

Thalweg

Fastest part of stream channel

Flow meter

Electronic device with impeller that is submerged to a certain depth Measures total depth and take velocity from average point

Accoustic Doppler current profiler

Sonar technology that records velocity at different depths

Velocity profile

Ave. velocity approximated at 60% of water depth or 40% of water height V=(V0.2h +2V0.4h +V0.8h)/4

Velocity area method

Cross section of a stream channel divided into sections and are added together