A few NOTES ON MORPHODYNAMIC Demonstrating OF VENICE Tidal pond Gary Parker, Spring, 2004

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Venice Lagoon was shaped by the activity of affidavit of mud and sand from waterways, ocean level ascent and compaction of fine-grained silt under its own weight. ...

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A few NOTES ON MORPHODYNAMIC MODELING OF VENICE LAGOON Gary Parker, Spring, 2004 Venice Lagoon was shaped by the activity of statement of mud and sand from streams, ocean level ascent and compaction of fine-grained dregs under its own particular weight. Today the wellspring of residue has been cut off, however the store keeps on compacting, or unite under its own particular weight. Combination is exacerbated by groundwater withdrawal and perhaps ocean level ascent created by an unnatural weather change.

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A CLOSER VIEW OF VENICE AND THE LAGOON

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EXNER EQUATION OF SEDIMENT CONSERVATION WITH COMPACTION Let  p = porosity, and c = 1 -  p division of bed volume that is strong (not pores). Exner from some level  b beneath which just structural impacts are felt to the water-residue interface  Apply Leibnitz where c D = solids part in naturally saved material at z =  and c b = solids portion at interface underneath which just tectonics is felt.

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EXNER EQUATION OF SEDIMENT CONSERVATION WITH COMPACTION contd. Characterize  t = -  b/t = structural subsidence rate. As a fine-grain layer compacts, c/t > 0, thus a subsidence rate because of compaction can be characterized as Thus Exner turns out to be Now by and large  t can be determined freely of the nearby procedure of statement. If there should arise an occurrence of the affidavit of fine-grained material, be that as it may,  c is a component of the statement itself: testimony incites compaction, which makes accomodation space for more testimony. Compaction advances as water is gradually crushed out of a mud layer by the procedure of combination.

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QUICK REVIEW OF CONSOLIDATION Consider a layer of fine-grained material (mud) limited by very penetrable sand beneath or more. The water table is situated in the upper sand layer. The water bolsters the water above in hydrostatic adjust, and the mud underpins its weight (short the light weight) by method for the contacts between the mud grains.

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QUICK REVIEW OF CONSOLIDATION contd. Sooner or later t = 0 a heap is set at first glance (over the water table). The sand layers rapidly react to the heap. At first, in any case, the particles in the mud layer don't have enough contacts to bolster the additional heap, so an abundance pore weight well beyond hydrostatic weight is made.

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QUICK REVIEW OF CONSOLIDATION contd. D'Arcy's law accept that groundwater streams from zones of high overabundance pore weight to low abundance pore weight. Characterizing the abundance piezometric head h e as h e = p e/(g), the connection takes the frame where w is the groundwater stream speed in the z bearing and K is the water powered conductivity of the mud. Overabundance pore weight in the mud layer is disseminated to the sand layers as delineated underneath:

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INTEGRATING CONSOLIDATION INTO A MORPHODYNAMIC MODEL Consider the subaqueous statement of mud with solidification

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INTEGRATING CONSOLIDATION INTO A MORPHODYNAMIC MODEL contd. Connection between harmony solids focus and profundity in mud: Here c D signifies the convergence of solids in naturally kept surface mud. Take note of that in this linearized treatment c E increments straightly with vertical separation beneath the surface. L c is a length scale connected with the linearization. Connection between overabundance piezometric head h e and the distinction between the real solids focus and the harmony esteem: where again L h is a length scale connected with solidification in a linearized treatment. Mass preservation of liquid stage:

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REDUCTION Now then So or decreasing, Thus utilizing D'arcy's law, Assuming water at hydrostatic weight at z =  and e.g. a permeable sand layer at z =  b , the limit conditions get to be

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REDUCTION contd. Lessen to

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CONCLUSION The coupled groundwater-morphodynamic issue is: to complete the issue plan, it is important to indicate relations for D and E of mud as elements of stream conditions. For instance, subsidence under compaction expands stream profundity, which may thus build the general rate of affidavit of fine-grained material. A similar model for hydrodynamics and disintegration and statement of mud ought to effectively fuse the impact of ocean level ascent, which will show up as a limit condition on the morphodynamic demonstrate.

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