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RIVER HYDRODYNAMICS AND SEDIMENT TRANSPORT Presentation byP.RAHUL REDDYG.ANUSHAP.MRUTHYUNJAY

1WHAT IS A SEDIMENT ?? Sediment refers to the conglomerate of materials, organic and inorganic, that can be carried away by water, wind or ice

FACTORS OF ORIGINLand and fluvial erosion at edgesGlacier melting phenomenonVolcanic eruptions of geological formationsScouring at river bottom

SEDIMENT TRANSPORT(or SEDIMENT LOAD TRANSPORT)SUSPENDED LOAD4

INSTRUMENTS TO CALCULATE SEDIMENT LOAD:HELLY SMITH SAMPLER

BOTTLE AND TRAP SAMPLER

OPTICAL BACKSCATTER POINT SENSOR

NUCLEAR SENSORSWHY SEDIMENT DEPOSITION IS IMPORTANT?Forms spawning zonesPromotes aquatic habitatControls the course of the river

FACTORS INFLUENCING SEDIMENT TRANSPORTIn general sediment transport is influenced by

GeologyGeomorphologyOrganic elements

External factors influencing sediment transportWater flowWater levelHuman influenceWATER FLOWFlow is required to initiate the transport

Whether sediment will be eroded, transported or deposited is depended on the particle size and the flow rate of the waterWATER FLOW FACTORSSTOKES SETTLING RATEBOUNDARY LAYER SHEAR STRESSES

vs = (g * (p f) * Dp2) / 18

vs = settling velocityg = gravitational constantp = particle densityf = fluid densityDp = particle diameter= fluid viscositySTOKES SETTLING RATE:BOUNDARY LAYER SHEAR STRESS = f * u2

= shear stressf = fluid densityu = characteristic velocity of turbulent flowSHEAR VELOCITYu = Sqrt(g * h * S)

u = shear velocity g = gravitational constant h = river depth S = river slopeWATER LEVELWater level is mainly influenced by weather conditions , seasonal effects and Local topographyHUMAN INFLUENCEAnthropogenic factors, such as dams and altered land use will affect both the sediment load and sediment transport rate

The Elwha Dam was removed as part of the Elwha River Restoration project. This project removed two major dams to improve natural sediment transport levels along the river, as well as opening the waterway to salmon migration and spawning. Too much? Too little?SEDIMENT LEVELS

TOO MUCHHigh TURBIDITYAlgal bloomsDeposition build upDisrupt natural aquatic migration

Sediment deposition is considered extreme when it exceeds the recommended or established TMDL.

22TOO LITTLENew habitats cannot be formedNo growth of submerged vegetationAlter Ecosystem

Mainly caused due to man made structures such as Dams , barriers.

CONTAMINATED SEDIMENT:Contaminated sediments are the accumulated riverbed materials that contain toxic or hazardous substances that are detrimental to aquatic, human or environmental health.

The most problematic contaminants in both bedded and suspended sediment are metals and persistent bioaccumulative toxics (PBTs), such as pesticides and methyl mercury.24SCOUR

25SCOUR Monitoring equipmentSONAR

MAGNETIC SLIDING COLLAR

FLOAT OUT DEVICEGROYNEAgroyneis a rigidhydraulic structurebuilt from an ocean shore or from a bank that interrupts water flow and limits the movement ofsediment

Groyne at Ennore beach, ChennaiBREAKWATERSBreakwatersare structures constructed on coasts as part ofcoastal defence or to protect an anchorage from the effects of bothweatherandlongshore drift

DROP STRUCTURE Adrop structure, also known as agrade control,sill, orweir, is a manmade structure, typically small and built on minor streams, or as part of a dam'sspillway, to pass water to a lower elevation while controlling the energy and velocity of the water as it passes over.

REFERENCES:http://www.fondriest.com/environmental-measurements/parameters/hydrology/sediment-transport-deposition/#std1

www.vliz.be

A textbook on Hydraulic structures by S.K.GARGTHANK YOU