Beachrocks in togo progress report


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Beachrocks in togo progress report

  1. 1. Beachrocks in Togo<br />Progress report<br />Guido Rutten<br />
  2. 2. Timeline<br />
  3. 3. Case: Togo<br />Figure 1 Location of the project. Image courtesy:;; Google Earth.<br />
  4. 4. Case: Togo (2)<br />Exposure of beachrocks<br />Unusuallength of formation (>100km)<br />Data availabilitythroughcontinuousobservation<br />A uniquecombination of system boundaries<br />
  5. 5. Research proposal<br />Research topics<br />Beachrocks &<br />shoreline movement<br />Controls <br />Initialgeometry<br />Formation of beachrocks<br />Weathering of beachrocks<br />Diageneticprocesses<br />Controls<br />Geomorphological setting<br />Destructionrates<br />Impact ondynamicequilibrium<br />Shoreline response<br />Response to low-crestedstructures<br />
  6. 6. Research proposal (2)<br />“Weathering of beachrock remains a ratheruntouched topic”<br />(Gischler, 2007)<br />Area of focus<br />
  7. 7. Research proposal (3)<br />Formation vs. destruction<br />Whystudyweathering of beachrock (and notitsformation)?<br />What is the potential and reliabilityof beachrock as a paleoenvironmental indicator? (e.g. tsunamis)<br />Scientific<br />How long will the beachrock in Togo continue to protect the shoreline?<br />(Coastal)<br />Engineering<br />Can we use beachrock,naturalorartificial, in anecodynamicapproachto shoreline protection?<br />Can we predict the occurrenceand characteristics of beachrock in deltaïc settings?<br />Oil & Gas<br />What is the reservoir potentialof beachrock?<br />
  8. 8. Research proposal(4)<br />Research Question:<br /> What is the relationship between the evolution of the shoreline profile in Togo and the exposure and characteristics of beachrock along this shoreline since 1975, <br /> and how can we use this knowledge to predict the impact of beachrock on the shoreline evolution in the future?<br />Research questions<br />
  9. 9. Research proposal(5)<br />Subquestions:<br />(a) What is the provenance of beachrock along the coast of Togo and what are its characteristics in terms of geometry, cementation type/degree and discontinuities?<br />(b) How has the Togo shoreline developed since the first exposure of beachrock in the 1980’s? <br />(c) Is there a significant relationship between the answers to question (a) and (b)?<br />(d) How does this relationship relate to existing theories concerning beachrock formation and can it be used to predict future shoreline evolution?<br />Research questions<br />
  10. 10. Methodology<br />Processflow<br />
  11. 11. Methodology<br />Dominant parameters<br />
  12. 12. Methodology<br />Dominant parameters<br />integration<br />over time<br />
  13. 13. Methodology<br />Scaleapproach<br />Microscale<br /> Togo CaseMesoscaleGeneric<br />Macroscale<br />
  14. 14. Methodology<br />Microscale (cross-shorecross-section)<br />Blivi (1998)<br />Amieux et al (1999)<br />Blivi (1998)<br />
  15. 15. Methodology<br />Mesoscale (a few hundred meters longshore)<br />Microscale<br />cross-sections<br />Airborneimagery<br />interpretation<br />
  16. 16. Methodology<br />Macroscale (multiple kilometers longshore)<br />diagenesis: cement alteration in time<br />Introduction of time component:<br />multiple exposures in time<br />Gradualchange in longshoredirection<br />temporal variation<br />
  17. 17. Methodology<br />Macroscale (multiple kilometers longshore)<br /> On a macroscale, the relationshipbetweenweathering and beachrock characteristicswillbedifficult to examine.<br />Other research opportunitiesinclude:<br />Spatialvariation of <br />(a) age,<br /> (b) width,<br />(c) inclination;<br />+ rel. to regionalgeology<br />2. Influence of submergedlow-crestedstructureson shoreline development<br />
  18. 18. Field Campaign<br />Planning<br />Field Campaign term: 02.05.2011-20.06.2011<br />Upon Return:<br />
  19. 19. Field Campaign<br />Activities<br />
  20. 20. Goals of the Project<br />The goals of this project can be denoted as follows:<br />A. Understanding processes in beachrock formation and erosion<br /> Understanding how the physical and geometrical characteristics of beachrock affect itserosion; Investigating how this fits in the existing theories of beachrock formation.<br />B. Defining an erosion prognosis and identifying weak zones in shoreline<br /> Given the knowledge in goal A; <br />Determining how erosion will continue in the near future; <br />Identification of weak zones related to the characteristics of the beachrock in place.<br />C. Defining an ecodynamic approach to shoreline protection<br /> For the case of Togo and similar cases; Defining a shoreline protection approach that takes into account, and benefits from the results of goal A.<br />Image courtesy<br />
  21. 21. Workingtowards the goals<br />In tropic to subtropicregions, beachrock formation is likely to occur. <br />Exposed beachrocks canfixate a shoreline, reducingitscapacity to maintaincoastlineequilibrium, inducinglateralshiftingof shoreline retreat.<br />Betterunderstanding of regionalgeologycan help in determining the probability of beachrock occurrence<br />Intermediateobservations<br />
  22. 22. Topics of furtherattention<br />Details and impact of multiple exposuresthrough time<br />Diageneticmineralogicalsequence<br />Bacterial and chemicalaction<br />Variability of wave energy (lateral and spatial)<br />
  23. 23.
  24. 24. Modelling?<br />Microscale: 2D cross-shore model (Xbeach?)<br />Wave impact<br />Influencetop surface to MSL oncross-shore sediment transport<br />Mesoscale: 3D/ depth-averaged (Delft3D?)<br />Wave energy distribution withdifferentialweathering<br />cf. Ranasinghe and Turner (2006): Shoreline response to submergedstructures: A review<br />
  25. 25. Field campaignfinances<br />* Universiteitsfonds and KIVI NIRIA fund are not confirmed. In case of non-approval, own contribution will be raised and additional sources of funding will be sought after.<br />** The student’s continued expenses in The Netherlands (housing, university fees) are not taken into account in this overview.<br />
  26. 26. Checklist beforedeparture<br />Logistics:<br /><ul><li> Visa
  27. 27. Medical
  28. 28. Housing
  29. 29. Cooperationlocalcontacts</li></ul>Research:<br /><ul><li>Reservationsforlaboratory
  30. 30. Regionalgeologyassessment
  31. 31. Sampling procedure</li></li></ul><li>Weatheringprocesses<br />Physicalweathering<br />Abrasion – dependsonproperties of movingparticles<br />Crystal growth<br />Thermalexpansion<br />Stress release<br />Hydraulicaction<br />Biologicalweathering<br />Antropogenic<br />Chemical weathering<br />Dissolution<br />Hydration<br />Hydrolysis<br />Oxidation<br />Biological<br />
  32. 32. Relevant literature<br />Amieux, P. (1989), "Cathodoluminescence of carbonate-cemented Holocene beachrock from the Togo coastline (West Africa): an approach to early diagenesis," Sedimentary Geology, vol. 65, pp. 261-272.<br />Blivi, A. (1998). "Quelques aspects du beach-rock dans le golfe du Bénin : le cas du Togo." Revue Cames: 43-56.<br />Gischler, E. (2007). "Beachrock and intertidal precipitates." Geochemical sediments & Landscapes. In Blackwell Publishing: 365–390.<br />Kindler, P. and R. Bain (1993). "Submerged upper Holocene beachrock on San Salvador Island, Bahamas: implications for recent sea-level history." GeologischeRundschau82(2): 241-247.<br />Rossi, G. (1988). "The beach-rock: a natural protection against coastal erosion." Un example d'utilisationd'unedefensenaturellecontrel'erosionlittorale: le gres de plage37(1): 1-10.<br />Vousdoukas, M. I., A. F. Velegrakis, et al. (2009). "Morphology and sedimentology of a microtidal beach with beachrocks: Vatera, Lesbos, NE Mediterranean." Continental Shelf Research 29(16): 1937-1947.<br />Vousdoukas, M. I., A. F. Velegrakis, et al. (2007). "Beachrock occurrence, characteristics, formation mechanisms and impacts." Earth-Science Reviews 85(1-2): 23-46.<br />