Surface Water Chapter 9. Surface Water Movement Earth’s water supply is recycled

Surface WaterSurface Water

Chapter 9Chapter 9

Surface Water MovementSurface Water Movement

• Earth’s water supply is recycled

Surface Water MovementSurface Water Movement

• Runoff- water flowing down slope on earth’s surface– Vegetation allows for greater infiltration of

water into the ground.– Rate of precipitation can influence infiltration

and runoff rates– Soil with high amounts of humus allow for

greater infiltration.

Surface water movementSurface water movement

• Open soil pores and compaction will influence infiltration rates

• Gradual slopes allow for greater infiltration

Stream SystemsStream Systems

• Precipitation that does not enter the ground usually flows quickly across the ground and eventually collects into small channels. As the amount of run off increases the channels widen, deepen, and become longer.

Watersheds and DividesWatersheds and Divides

• Watershed- all the land area whose water drains into a stream system.

• Divide- high land area that separates watersheds

Stream LoadStream Load• Stream load- all the materials carried by a

stream– Solution- dissolved material carried by water.

Stream LoadStream Load

• Suspension- particles held up by the turbulence of moving water. – Varies with volume and velocity

Steam LoadSteam Load

• Bed Load- consist of sand, pebbles, cobbles that are too heavy to be suspended in the stream load. These materials may be “rolled” along the stream bed.

Stream VelocityStream Velocity

• The ability of a stream to move material is dependent on the volume and velocity of water.

• Discharge is a measure of the volume of water in a stream

• Discharge = width x depth x velocity

Stream VelocityStream Velocity

FloodplainFloodplain• Floods occur when water spills over the

sides of a stream channel.

• Floodplain- the broad flat area that extends out from a stream’s bank and is covered by water during flooding.

Stream DevelopmentStream Development

• Swift fast-moving water at high elevations carve a narrow pathway called a stream channel.

• The channel widens and deepens and is held in by the stream bank.

Stream DevelopmentStream Development

• Stream activity erodes a path through sediment or rock.

• A “v-shaped” valley forms and the stream cuts down until it reaches base level- the level at which it enters another stream or body of water.

• After the stream cuts down then it starts to erode the sides of the stream bank and the valley becomes wider.

Stream DevelopmentStream Development

Stream DevelopmentStream Development

• Meandering streams-form in gradually sloped wide u-shaped valleys. As the stream passes through this valley it will erode the sides of the stream bank and start to meander (bend or curve).

• Water on the outside of a meander will flow quickly (erosion) and water on the inside of the meander will flow slowly (deposition).

MeanderingMeandering

Ox Bow LakesOx Bow Lakes

Stream DepositionStream Deposition

• Alluvial fan- fan shaped deposition feature when rapidly moving water suddenly slows down

• Delta- triangular deposits that form as a stream enters a large body of water.

Stream DepositionStream Deposition

Stream DevelopmentStream Development

• Rejuvenation- stream activity resumes down cutting because of uplift or base level lowering.

Lakes and Freshwater WetlandLakes and Freshwater Wetland

• Lakes- a depression in the surface materials of a landscape that collects and holds water.

• Fill with water from streams, runoff, precipitation, and springs

• Form from the movement of rivers (ox bow lakes), streams that become blocked, glacial remains.

Lakes undergo changeLakes undergo change

• Lakes will fill with sediment over time and become part of the local landscape because of deposition.

Lakes undergo changeLakes undergo change

• Eutrophication- process of lakes becoming rich in nutrients from the surrounding watershed changing the life that lives in the lake.

Freshwater WetlandsFreshwater Wetlands

• Wetland- an area covered with water for a large part of the year. – Bog- not stream fed, rich in moss, acidic soil,

WetlandsWetlands

– Marsh- occur along the mouth of streams and where extensive deltas occur, lush grasses, encourage wildlife

WetlandsWetlands

– Swamps- low lying areas near streams, shrubs and trees

WetlandsWetlands

• Importance of wetlands– Improve water quality– Habitat for migratory birds

• Destruction of wetlands– Filled in for agriculture and urban growth– From 1700-1980 the US lost 50% of its

wetlands to development