Abstract
The dynamics and geomorphological development of a trough blowout located at Fiona Beach in the Myall Lakes National Park in NSW, Australia are examined. Wind velocities and flow structure were measured utilising an array of miniature Rimco cup anemometers, Gill bi-vane and UVW instruments, and wind vanes. Flow measurements indicate that when the wind approaches the trough blowout parallel to the throat orientation, jets occur both in the deflation basin and along the erosional walls, relative flow deceleration and expansion occur up the depositional lobe, jets are formed over the depositional lobe crest accompanied by downwind flow separation on the leeward side of the lobe, and flow separation and the formation of corkscrew vortices occur over the crests of the erosional walls. Maximum erosion and transport occur up the deflation basin and onto the depositional lobe. Trough blowout morphologies are explained as a function of these flow patterns.
When the wind approaches the blowout obliquely, the flow is steered considerably within the blowout. The degree and complexity of topographic steering is dependent on the blowout topography. The flow is usually extremely turbulent and large corkscrew vortices are common. The local topography of a blowout can be very important in determining flow patterns, overall sand transport and blowout evolutionary conditions and paths.
Estimates of potential sand transport within the blowout may be up to two orders of magnitude lower than actual rates if remote wind data are used.
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Adamson, D. A., Selkirk, P. M. and Colhoun, E. A.: 1988, ‘Landforms of Aeolian, Tectonic and Marine Origin in the Bauer Bay-Sandy Bar Region of Subantarctic Macquarie Island’, Papers and Proc. Royal Soc. of Tasmania 122, 65–82.
Bagnold, R. A.: 1941, The Physics of Blown Sand and Desert Dunes, Chapman and Hall, London.
Borichansky, L. S. and Mikhailov, V. N.: 1966, ‘Interaction of River and Sea Water in the Absence of Tides’, in Scientific Problems of the Humid Tropical Deltas and their Implications, UNESCO, pp. 175–180.
Carter, R. W. G., Hesp, P. A. and Nordstrom, K. F.: 1990, ‘Erosional Landforms in Coastal Dunes’, in K. F. Nordstrom, N. P. Psuty and R. W. G. Carter (eds.), Coastal Dunes: Form and Process, John Wiley and Sons, London, pp. 217–249.
Cooke, R., Warren, A. and Goudie, A.: 1993, Desert Geomorphology, UCL Press, London.
Cooper, W. S.: 1958, ‘Coastal Sand Dunes of Oregon and Washington. Geol. Soc. Amer. Mem. 72.
Cooper, W. S.: 1967, ‘Coastal Sand Dunes of California Geol. Soc. Amer. Mem. 101.
Cowles, 1898, ‘The Ecological Relations of the Vegetation on the Sand Dunes of Lake Michigan’, Botannical Gazette 27, 97–117.
Davies, J. L.: 1980, Geographical Variation in Coastal Development, Longman, London.
de Castro Lopo, L.: 1979, ‘Newcastle to Forster: A Study of the Coast’, in J. C. R. Camm and R. J. Loughran (eds.), Newcastle Studies in Geography, Univ. Newcastle, N.S.W. Australia, pp. 47–59.
Eriksson, P. G., Nixon, N., Snyman, C. P. and Bothma, J. duP: 1989, ‘Ellipsoidal Parabolic Dune Patches in the Southern Kalahari Desert’, J. Arid Environments 16, 111–124.
Esler, A. E.: 1970, ‘Manawatu Sand Dune Vegetation’, Proc. N.Z. Ecological Society 17, 41–46.
Finnigan, J. J., Neil, D., Lees, B. G., Croome, R. J. and Woodgate, M.: 1989, ‘Modelling the Wind Flow Pattern Around a Parabolic Sand Dune’, Proc. 8th Biennial Conf. of the Simulation Soc. of Australia and the Internat. Assoc. for Mathematics and Computers in Simulation, 457–462.
Fryberger, S. G. and Dean, G.: 1979, ‘Dune Forms and Wind Regime’, in E. D. McKee (ed.), A Study of Global Sand Seas, Geological Survey Prof. Paper 1052, US Govt. Printing Office, Washington, pp. 137–169.
Gares, P. A. and Nordstrom, K. F.: 1987, Dynamics of a Coastal Foredune Blowout at Island Beach State Park, N.J. Proc. Coastal Sediments '87, ASCE, pp. 213–221.
Glen, M.: 1979, ‘Glossary’, in E. D. McKee (ed.), A Study of Global Sand Seas, Geol. Survey Prof. Paper 1052, pp. 399–407.
Hack, J. T.: 1941, ‘Dunes of the Western Navajo Country’, Geographical Review 31, 240–263.
Hails, J. R. and Bennett, J. M.: 1981, ‘Wind and Sediment Movement in Coastal Dune Areas’, Proc. 17th Internat. Coastal Engineering Conf, ASCE, pp. 1565–1575.
Harris, C.: 1974, ‘Wind Speed and Sand Movement in a Coastal Dune Environment’, Area 6, 243–249.
Hesp, P. A. and Thom, B. G.: 1990, ‘Geomorphology and Eevolution of Active Transgressive Dunefields’, in K. F. Nordstrom, N. P. Psuty and R. W. G. Carter (eds.), Coastal Dunes: Form and Process, John Wiley and Sons, London, pp. 253–288.
Hogbom, I.: 1923: ‘Ancient Inland Dunes of Northern and Middle Europe’, Geografiska Annaler 113–242.
Hsu, S. A.: 1974, ‘Computing Eolian Sand Transport from Outine Weather Data’, Proc. 14th Coastal Engineering Conf. 1619–1626.
Hunt, J. C. R. and Snyder, W, H.: 1980, ‘Effects of Stratification on the Flow Structure and Turbulent Diffusion Around Three-Dimensional Hills, Part 1: Flow Structure’, J. Fluid Mech. 96, 671–704.
Jennings, J. N.: 1957, ‘On the Orientation of Parabolic or U-Dunes’, Geographical J. CXXIII, 474–480.
Jensen, N-O. and Zeeman, O.: 1990, ‘Numerical Modelling of Transverse Dune Forms’, in Extended Abstracts, NATO Advanced Workshop on Sand, Dust and Soil in Their Relation to Aeolian and Littoral Processes, 14–18 May, 1990, Sandbjerg, Denmark.
Jungerius, P. D.: 1984, ‘A Simulation Model of Blowout Development’, Earth Surface Processes and Landforms 9, 509–512.
Jungerius, P. D., Verheggen, A. J. and Wiggers, A. J.: 1981, ‘The Development of Blowouts in ‘De Blink’, a Coastal Dune Area near Noordwijkerhout, The Netherlands’, Earth Surface Processes and Landforms 6, 375–396.
Kaimal, J. C. and Finnigan, J. J.: 1994, Atmospheric Boundary Layer Flows, Oxford University Press, U.K.
King, C. A. M.: 1972, Beaches and Coasts, Edward Arnold, London.
Krothapalli, A., Baganoff, D. and Karamcheti, K.: 1981, ‘On the Mixing of a Rectangular Jet’, J. Fluid Mech. 107, 201–220.
Lancaster, N.: 1986, ‘Dynamics of Deflation Hollows in the Elands Bay Area, Cape Province, South Africa’, Catena 13, 139–153.
Landsberg, H. and Riley, N. A.: 1943, ‘Wind Influences on the Transportation of Sand over a Michigan Sand Dune’, Proc. 2nd Hydraulics Conf. Bulletin 27, Univ. Iowa Studies in Engineering.
List, E. J.: 1982, ‘Turbulent Jets and Plumes’, Ann. Rev. Fluid Mech. 14, 189–212.
Marta, M. D.: 1958, ‘Coastal Dunes: A Study of the Dunes at Vera Cruz’, Proc. Coastal Engineering Conf. 6(28), 520–530.
Melton, F. A.: 1940, ‘A Tentative Classification of Sand Dunes: Its Application to Dune History in the Southern High Plains’, J. Geology 48, 113–174.
Mulhearn, P. J. and Bradley, E. F.: 1977, ‘Secondary Flows in the Lee of Porous Shelterbelts’, Boundary-Layer Meteorol. 12, 75–92.
Olson, J. S.: 1958, ‘Lake Michigan Dune Development. I. Wind Velocity Profiles’, J. Geology 66, 254–263.
Pluis, J. L. A.: 1992, ‘Relationships between Deflation and near Surface Wind Velocity in a Coastal Dune Blowout’, Earth Surface Processes and Landforms 17, 663–673.
Ranwell, D. S.: 1972, Ecology of Salt Marshes and Sand Dunes, Chapman and Hall, London.
Ritchie, W.: 1972, ‘The Evolution of Coastal Sand Dunes’, Scottish Geographical Magazine 88, 19–35.
Robertson-Rintoul, M. J.: 1990, ’A Quantitative Analysis of the Near-Surface Wind Flow Pattern over Coastal Parabolic Dunes’, in K. F. Nordstrom, N. P. Psuty and R. W. G. Carter (eds.), Coastal Dunes: Form and Process, John Wiley and Sons, London, pp. 57–78.
Smith, H. T. U.: 1960, Physiography and Photo Interpretation of Coastal Sand Dunes, Final Report Contract NONR-2242(00), Office of Naval Research, Geogr. Branch.
Svasek, J. N. and Terwindt, J. H. J.: 1974, ‘Measurements of Sand Transport by Wind on a Natural Beach’, Sedimentology 21, 311–322.
Thom, B. G., Shepherd, M. J., Ly, C., Roy, P., Bowman, G. M. and Hesp, P. A.: 1992, Coastal Geomorphology and Quaternary Geology of the Port Stephens-Myall Lakes Area, Dept. of Biogeography and Geomorphology, A.N.U. Monograph No. 6. ANU Tech P.L., Canberra.
van der Meulen, F. and Jungerius, P. D.: 1989, ‘Landscape Development in Dutch Coastal Dunes: The Breakdown and Restoration of Geomorphological and Geohydrological Processes’, Proc. Royal Soc. of Edinburgh 96B, 219–229.
Verstappen, H. Th.: 1968, ‘On the Origin of Longitudinal (Seif) Dunes’, Zeitschrift fur Geomorphologie, NF 12, 200–220.
Wright, L. D.: 1977, ‘Sediment Transport and Deposition at River Mouths: A Synthesis’, Geological Soc. America Bulletin 88, 857–868.
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Hesp, P.A. Flow dynamics in a trough blowout. Boundary-Layer Meteorol 77, 305–330 (1996). https://doi.org/10.1007/BF00123530
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DOI: https://doi.org/10.1007/BF00123530