Water Movements

Laminar and Turbulent Flow

Reynolds Number (Re)Laminar Re<2300Transient 2300<Re<4000Turbulent Re>4000

Turbulence is significant in:

• conduction of heat (eddy conduction)• diffusion of dissolved substances (eddy

diffusion)• viscosity (eddy viscosity)

Surface Waves

Deep Water Wave

Water Movement in a Surface Wave

Shallow Water Waves

Fetch

Lake Thunderbird

Whitecaps on Lake Michigan

Langmuir Circulation

Causes of Surface Currents

• Wind• Change in atmospheric pressure• Horizontal density gradients• Influx of water

Surface Currents in Lake Erie

Rip Current in Lake Erie

Currents in a Stratified Lake

Layers remain stable if the shearing force between them is low; Richardson number (Ri) remains higher than 0.25.

Coriolis Effect on water movement

Thermal Bars

Formation of a Seiche

Bimodal Seiche

Seiche on Lake Erie

Seiche traces from different parts of Lake Huron

Inflow and outflow in Galich Lake

Lake Sam Reyburn, TX

Richardson number = shearing force between layers

From Fernandez and Imberger (2006)

Table 7-1Velocity (cm/sec) Substrate Diameter range (mm)

3-20 Silt, mud, organic debris <0.02

20-40 Fine sand 0.1 - 0.3

40-60 Coarse sand to fine gravel 0.5 – 8

60-120 Small - large gravel 8 – 64

120-200 Large cobbles to boulders >128

Movement of Water in a Stream Channel

Run and Riffle

Standing Wave in Stream

Standing waves on the Colorado River in the Grand Canyon

Discharge and Gage Height

Rivers Reservoirs Natural LakesWater-level Fluctuations

Large, rapid, irregular; flooding

Large, irregular Small, stable

Inflow Runoff from surface irregular and seasonal; groundwater stable

From river and tributaries; internal flows complex

From low order streams, groundwater

Outflow Discharge irregular Highly irregular Stable; outflow shallow and groundwater

Flushing Rate Rapid, unidirectional, horizontal

Short, variable (weeks)

Long, years