Download - sediment transport Seminar
Title Layout
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