Water Movements Laminar and Turbulent Flow Reynolds Number

Water Movements

Laminar and Turbulent Flow

Reynolds Number (Re) Laminar Re<2300 Transient 2300<Re<4000 Turbulent Re>4000 Re = inertial forces: viscous forces

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 -1 Velocity (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 78 years of record: Min = 1460 cfs (1964) Max = 399, 000 cfs (2011) Median = 4930 cfs Mean = 12200 cfs

Rivers Reservoirs Natural Lakes Water-level Fluctuations Large, rapid, irregular; flooding Large, irregular Small, stable Inflow Runoff from surface From river and irregular and seasonal; tributaries; internal groundwater stable 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