WATER FLOW

Do Now:What is this picture showing?

A dam…with goats.The Cingino Dam in Italy (169ft tall) is a common place to find the Alpine Goat- they lick the sea salt left from the water

Water Flow

The flow of water is directly effected by weather and seasonsFaster flow during and after rainSlower flow during summer when

evaporation rates are higher Water flow has an impact on water

quality

Flow and Water Quality Large, swiftly flowing rivers are less affected by pollution Small streams will have a larger impact

They have less capacity to dilute and degrade wastes. Flow determines the kinds of organisms that can live in

the stream Some need fast-flowing areas; others need quiet pools

Flow affects the amount of silt and sediment carried by the stream. Sediment introduced to slow-flowing streams will settle quickly

to the stream bottom. Fast moving streams will keep sediment suspended longer in

the water column. Fast-moving streams generally have higher levels of

dissolved oxygen

Changes to Water Flow

Dams, irrigation, droughts and municipal use decrease the water supply which affects water flow

Riparian Zones- unique transition ecosystems between water and landProvides habitats for many different

organismsChanging the water flow can increase or

decrease the water level which will effect these habitats

Riparian Area

Riparian Area

Functions of Riparian Areas Provides habitats for many organisms

Amphibians, insects, birds, mammals Acts as a buffer for the water

Prevents erosion: root systems from plants hold the soil in place

Protects against pollution: Vegetation helps to absorb runoff instead of entering the water directly

Provides scenic beauty for recreation areasFishing, boating, swimming

Dams

Dams have been used throughout history to change water flow for human needsFlood ControlElectricityIrrigationRecreation

Oldest Dam: The Quatinah Barrage or Lake Homs Dam, located in Syria

The dam was constructed 1319-1304 BC, and was expanded in 1934 and 1938.Creates Lake Homs, supplying water for the city of Homs through canals.

Largest Hydroelectric Dam: Three Gorges Dam in ChinaSpans the Yangtze River *lots of controversy over the construction of this dam* Three Gorges Dam Video

The Good….

Dams allow for flood control Provides area of recreation which

increases economics in an area Can be used for Hydroelectricity

Water behind the dam (reservoir) is let through the dam at specific rates to spin turbines which creates electricity

Reservoirs behind the dam are used for drinking water and irrigation

Hoover Dam used for Hydroelectricity

Dams with spillway for flood control

The Bad…. Disrupts riparian zones

New dams cause flooding upstream and drying downstream Endangered species of fish

Fish cannot migrateSome dams have fish “ladders” to allow them to move

through Water flow is disrupted

Reservoirs have higher rates of evaporationSlow flow decreases dilution of pollutantsTemperature of water changes (affects DO levels)

Heightened security due to acts of terrorism Periods of drought have larger effect of reservoir than

flowing water

There are 20 dams along the Rio Grande

• There has been fighting between states and US/Mexico over who controls the water, how much should be let downstream

• Mexico receives very little of the water and is forced to use expensive methods for irrigation which hurts the economy and sale of their crops

Water flow slows down abruptly causing:- Low oxygen levels as water slows

- Temperature changes- Waste buildup- Sedimentation

Summary Water flow is a key factor in the water quality

for aquatic ecosystems Dams have many benefits but also cause

ecological and economic disruption Watch the video and use the notes to answer

the Ticket Out question:Riparian Areas Video

Ticket Out: What impact would the construction of a new dam have on the riparian areas both upstream and downstream?