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Trees as flood sensors

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In many settings, trees growing on floodplains provide an important source of indirect evidence that may be used to infer the occurrence, extent, and magnitude of floods prior to direct observations. That evidence may take several forms, including external scars caused by abrasion or impact from floating debris, anatomical changes within the annual growth increment following prolonged stem or root inundation, or tilting or uprooting due to the hydraulic pressure of floodwaters. Likely the most useful characteristic of paleoflood studies based on floodplain trees is their relatively high temporal resolution and dating accuracy compared to most other methods. Dendrochronological methods can routinely date past floods to the year of their occurrence and, in rare cases, can estimate the timing of floods that occur during the growing season to within two weeks. This high degree of chronological control, which is surpassed only by that provided by direct observation or instrumentation, can be used to determine whether floods in separate watersheds were synchronous or offset by several years and test hypotheses that suppose linkages between extreme floods and specific forcing mechanisms. Furthermore, the wide geographic distribution of tree species with dateable rings combined with the broad suite of methods available to examine interconnections between floods and tree growth allow this style of paleoflood hydrology to be applied to many settings that are not suitable for techniques that depend on geological evidence. Future paleoflood research involving tree rings will need to strike a balance between improving our understanding of the biological and fluvial processes that link tree growth to past events, and providing answers to questions about flood dynamics and hazards that are needed to safeguard people and property from future floods.

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Trees as flood sensors

  1. 1. Maison des Sciences de l’Homme – Alpes | Université de Grenoble | June 27-30, 2016 TREES AS FLOOD SENSORS
  2. 2. Source: Greg Brooks, Geological Survey of Canada
  3. 3. THE RIGHT TREES
 IN THE RIGHT LOCATIONS CAN PROVIDE RELIABLE AND PRECISE INSIGHTS INTO THE OCCURRENCE AND MAGNITUDE OF PAST FLOODS.
  4. 4. TO TREES, RIVERS ARE HAZARDS Source: Joe Zeleznik, North Dakota State University
  5. 5. IN WHAT MANNER DO RIPARIAN TREES PRESERVE EVIDENCE OF PALEOFLOODS?
  6. 6. 3TILTING OR UPROOTING BY HYDRAULIC PRESSURE
  7. 7. 2ANATOMICAL SIGNATURES WITHIN TREE RINGS
  8. 8. 1SCARRING DUE TO IMPACT OR ABRASION
  9. 9. FUNDAMENTALS OF DENDROCHRONOLOGY
  10. 10. 12 EARLYWOOD LATEWOOD ONE GROWTH RING CONIFER
  11. 11. HOW MANY (COMPLETE) TREE RINGS ARE VISIBLE IN THIS MICROPHOTOGRAPH?
  12. 12. HOW MANY (COMPLETE) TREE RINGS ARE VISIBLE IN THIS MICROPHOTOGRAPH?
  13. 13. Source: Daniel Griffin, University of Minnesota
  14. 14. 1871 1872 1873 1874 Source: Daniel Griffin, University of Minnesota
  15. 15. NORTHWESTERN NEW MEXICO Source: Daniel Griffin, University of Minnesota
  16. 16. CRATER LAKE NATIONAL PARK
  17. 17. Source: Sarah Appleton, University of Minnesota
  18. 18. 1809 1811 181218081807 Source: Sarah Appleton, University of Minnesota
  19. 19. TREE-RING DATING IS NOT CONDUCTED BY SIMPLY COUNTING LAYERS (RINGS), BUT BY MATCHING PATTERNS ACROSS DOZENS OR HUNDREDS OF TREES.
  20. 20. TREE-RING DATING IS NOT CONDUCTED BY SIMPLY COUNTING LAYERS (RINGS), BUT BY MATCHING PATTERNS ACROSS DOZENS OR HUNDREDS OF TREES.
  21. 21. IN WHAT MANNER DO RIPARIAN TREES PRESERVE EVIDENCE OF PALEOFLOODS?
  22. 22. 1SCARRING DUE TO IMPACT OR ABRASION
  23. 23. ROBERT SIGAFOOS (1920-1995) UNITED STATES GEOLOGICAL SURVEY
  24. 24. A SHARP BLOW TO A TREE TRUNK, WHETHER MADE BY A LAWN MOWER, BY A BASEBALL BAT IN THE HANDS OF A SMALL BOY, OR BY DEBRIS CARRIED BY HIGH WATER, WILL CRUSH, AND THUS KILL, THE LIVING TISSUES BENEATH THE BARK AND THE WOOD. “ ” Sigafoos, 1964 Botanical evidence of floods and flood-plain deposition
  25. 25. Source: Mark’s Postcards from Beloit
  26. 26. IMPACT OR ABRASION SCARS Source: Juan Antonio Ballesteros-Cánovas , University of Bern
  27. 27. Source: Brian Luckman, University of Western Ontario
  28. 28. Source: NDSU Ag Comm
  29. 29. MISTASSINI RIVER, QUÉBEC Source: Jeff Dumais
  30. 30. Source: Annie Lagadec MISTASSINI RIVER, QUÉBEC
  31. 31. A SCAR-HEIGHT CHRONOLOGY WAS COMBINED WITH HYDRO-CLIMATIC DATA TO IDENTIFY CONDITIONS FAVORABLE TO TRIGGERING ICE JAMS. Source: Lagadec et al., Hydrological Processes, 2015
  32. 32. HIGH-GRADIENT RIVERS Source: Uday Kunwar Thapa, University of Minnesota
  33. 33. 2ANATOMICAL SIGNATURES WITHIN TREE RINGS
  34. 34. QUERCUS
  35. 35. √ 24 OAK TREE RINGS (NORMAL ANATOMY) 18
  36. 36. OAK TREE RINGS (ANATOMY DISRUPTED BY FLOODING)
  37. 37. 11 THE RED RIVER OF THE NORTH
  38. 38. 1997 15Source: Greg Brooks, Geological Survey of Canada
  39. 39. 42 SUBFOSSIL OAKS IN THE RED RIVER Source: Erik Nielsen, Manitoba Geological Survey
  40. 40. QUERCUS MACROCARPA (MICHX.) GROWING ALONG THE RED RIVER, MANITOBA, CANADA, CONTAIN AN ANATOMICAL SIGNATURE RELATED TO HIGH-MAGNITUDE 19TH-CENTURY FLOODS. “ ” St. George and Nielsen, 2000 Geology
  41. 41. FLOOD RINGS EXTENDED THE EVENT RECORD FOR THE RED RIVER OF THE NORTH BACK TO THE MID-1600S. Source: St. George and Nielsen, The Holocene, 2003
  42. 42. PHENOLOGY
  43. 43. FLOODING CAUSES OAKS TO FORM NARROW EARLYWOOD VESSELS, BUT ONLY IF IT OCCURS AFTER BUDSWELL OR INTERNODE EXPANSION. Source: Copini et al, , Frontiers in Plant Science, in press
  44. 44. Source: Wikipedia contributor Shannon1 MISSISSIPPI RIVER
  45. 45. BOTTOMLAND HARDWOODS, MISSISSIPPI Source: Ma hew Therrell, University of Alabama
  46. 46. 3TILTING OR UPROOTING BY HYDRAULIC PRESSURE
  47. 47. Source: Juan Antonio Ballesteros-Cánovas , University of Bern
  48. 48. PALEODISCHARGE ESTIMATES STRUCTURAL ENGINEERING
  49. 49. Source: Ballesteros et al., Journal of Hydrology, 2015 TILTED TREES GROWING IN FLOODPLAINS EXHIBIT REACTIONS CAUSED BY FLOOD, AND THEIR STRUCTURAL BEHAVIOR MAY BE LINKED TO FLOW CONDITIONS.
  50. 50. TAGUS RIVER, SPAIN Source: Flickr user dailymatador
  51. 51. MECHANICAL MODELS ARE ABLE TO REPRODUCE THE OBSERVED TREE DEFORMATION, BUT ALSO CONSISTENTLY UNDERESTIMATE PEAK DISCHARGE. Source: Ballesteros et al., Journal of Hydrology, 2015
  52. 52. 10
  53. 53. THE GLOBAL TREE-RING NETWORK INCLUDES DATA FROM THOUSANDS OF LOCATIONS, BUT MOST (ALL?) OF THESE TREES ARE NOT AFFECTED BY FLOODING! Source: St. George, Past Global Changes Magazine, 2014
  54. 54. THE RIGHT TREES
 IN THE RIGHT LOCATIONS CAN PROVIDE RELIABLE AND PRECISE INSIGHTS INTO THE OCCURRENCE AND MAGNITUDE OF PAST FLOODS.
  55. 55. Source: Ballesteros-Cánovas et al., Progress in Physical Geography, 2015 PALEOFLOOD STUDIES BASED ON TREE RINGS ARE STILL FEW, AND HAVE BEEN CONDUCTED ALMOST EXCLUSIVELY IN EUROPE, CANADA, AND THE UNITED STATES.
  56. 56. THE HISTORY OF PAST FLOODS, NOT THE HISTORICAL IDEALIZATION OF THEIR FUTURE POSSIBILITIES, IS THE UNDERSTANDABLE BASIS UPON WHICH PEOPLE MAY BE GUIDED TO EFFECTIVE ACTION. “ ” Baker et al., 2002 The Scientific and Societal Value of Paleoflood Research
  57. 57. THE RED RIVER OF THE NORTH
  58. 58. 1826
  59. 59. THE FORTS NOW STAND LIKE A CASTLE OF ROMANCE IN THE MIDST OF AN OCEAN OF DEEP CONTENDING CURRENTS, THE WATER EXTENDING FOR AT LEAST A MILE BEHIND THEM… “ ” Francis Heron of the Hudson’s Bay Company May 1826
  60. 60. 1826

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