River action / fluvial erosion and deposition landforms :Geomorphology

RIVERS action

ByNarendranath Guria

HYDROLOGIC CYCLEINFILTRATIONRUNOFFTRANSPIRATIONEVAPORATIONPRECIPITATION

Water cycle

FLUVIALANY STREAM RELATED PROCESSES NO MATTER IF THEY ARE DEPOSITIONAL OR EROSIONAL

ALLUVIUM IS THE NAME FOR ANY STREAM DEPOSITED MATERIAL

ALLUVIUM

DRAINAGE BASINTHE AREA WHERE PRECIPITATION DRAINS AND ULTIMATELY MAKES ITS WAY TO THE OCEAN

EVERY DRAINAGE BASIN IS DEFINED BY RIDGES THAT FORM DRAINAGE DIVIDES

DRAINAGE DIVIDES DEFINE A WATERSHED (WATER-RECEIVING)

GROUNDWATERWATER BENEATH THE SURFACE THAT IS BELOW THE SOIL-ROOT ZONE

ZONE OF AERATION - VADOSE ZONE

WATER TABLEZONE OF SATURATION - PHREATIC ZONE

GROUNDWATER

PERMEABLE ROCKWATER CAN FLOW THROUGH ROCK/SOIL

IMPERMEABLE ROCKWATER DOES NOT FLOW THROUGH ROCK OR SOIL

AQUIFERA BODY OF ROCK THAT CONDUCTS GROUNDWATER IN USABLE AMOUNTS - PERMEABLE

AQUICLUDE/AQUITARDAN IMPERMEABLE ROCK THAT DOES NOT CONDUCT WATER IN USABLE AMOUNTS

Rivers

BASE LEVELSEA LEVEL - THE ULTIMATE BASE LEVEL

LOCAL BASE LEVEL - STREAMS, LAKES, RESISTANT ROCKS, ETC.

BASE LEVEL

DRAINAGE PATTERNSPARALLEL-PINNATERADIALANNULARTRELLISRECTANGULARDENDRITICDERANGED

PARALLEL-PINNATE

RADIAL DRAINAGE

ANNULAR

TRELLIS

RECTANGULAR

DENDRITIC

LATERAL MIGRATIONMEANDERINGBRAIDEDSTRAIGHT

meandering

BRAIDED STREAM

STRAIGHT STREAM

HYDRAULIC ACTIONDUE TO TURBULENCE IN WATERSQUEEZING AND LIFTING OF ROCK

ABRASIONGRINDING AND CARVING UP OF MATERIAL LIKE LIQUID SANDPAPER

SMOOTHING AND ROUNDING OF ROCK

COBBLES BECOME PEBBLESPEBBLES BECOME SANDSAND BECOMES SILTSILT BECOMES CLAY

THE ABILITY OF A STREAM TO ERODE AND TRANSPORT MATERIALS IS RELATED TO ITS SPEED (VELOCITY)

FACTORS THAT DETERMINE SPEED

GRADIENTSHAPE, SIZE, ROUGHNESS OF CHANNEL

LONGITUDINAL PROFILE

STREAM TRANSPORT OR LOAD

DISSOLVED LOAD - SOLUTION THAT OFTEN CAN BE BROUGHT IN BY GROUNDWATER-FERTILIZERS/PESTICIDES/CHEMICAL

SUSPENDED LOAD - FINE-GRAINED BITS AND PIECES OF ROCK

BED LOAD - COARSER MATERIAL CARRIED ALONG BOTTOM

TYPES OF BED LOADSALTATION - LEAPING, SKIPPING, JUMPING ALONG BOTTOM

TRACTION - MATERIAL IS DRAGGED OR ROLLED ALONG BOTTOM

Stream load

NICKPOINTS OR KNICKPOINTS

ABRUPT CHANGE IN GRADIENT ALONG THE LONGITUDINAL PROFILE

EXAMPLES ARE WATERFALLS, CASCADES, OR RAPIDS

WATERFALLS LONELY PLANET PHOTO

CYCLE OF EROSIONEVOLUTION OF A LANDFORM AS DEVELOPED BY THE GEOGRAPHER WILLIAM MORRIS DAVIS

STAGES ARE YOUTH, MATURITY, OLD AGE, AND REJUVENATION

YOUTHDEEP V-SHAPED VALLEYBROAD UPLANDSSTEEP-SIDED VALLEY WALLS

youth

youthful

MATURITYSTREAM BEGINS LATERAL MIGRATION

BROADENED FLOODPLAIN

Mature stage

mature

OLD AGEMEANDERING STREAM WITH MANY CUTOFFS AND OXBOWS

BROAD FLOODPLAIN

Rivers shape the landscape

If there is a large bend in the river, the force of the water cuts through the land

Oxbow = an extreme bend in a river

Oxbow lake = the bend is cut off and remains as an isolated, U-shaped body of water

Old age

Old age

REJUVENATIONUPLIFTING OF LAND DURING OLD AGE STAGE

LEAVES ENTRENCHED MEANDERS

Entrenched meanders

STREAM DEPOSITIONAL FEATURES

FLOODPLAINNATURAL LEVEESYAZOO STREAMOXBOW LAKESMEANDER SCARS

LEVEE - YAZOO

OXBOW

STREAM TERRACESALLUVIAL TERRACES MARK PERIODS OF INCREASED STREAM ENERGY.

APPEAR PAIRED AT SIMILAR ELEVATIONS

Stream terraces

DELTASCLASSIC TRIANGLE

BIRD’S FOOT

delta

MISS RIVER DELTA

FLOODS10, 50, & 100 YEAR FLOODPLAINJOHNSTOWN FLOOD OF MEMORIAL DAY WEEKEND 1889

Thank Q