IJG  Vol.4 No.6 B , August 2013
Stability Analysis of Cliff Face around Kegon Falls in Nikko, Eastern Japan: An Implication to Its Erosional Mechanisms
Abstract: A waterfall highlights the locus of active fluvial erosion of bedrock, and its mechanism has been the subject of several studies; however, erosional processes remain to be clarified for specific rock structures composing a waterfall. Herein, the detailed morphology of cliffs around a waterfall is examined by a terrestrial laser scanning (TLS) approach to analyze erosional processes occurring in the cliffs. The study site is Kegon Falls in Japan, which has a vertical drop of surface water from the top of its cliff and groundwater outflows from its lower portion. The entire cliff is mostly overhanging and minor rockfalls are often observed. The latest major rockfall occurred in 1986, causing an approximate 8-m upstream shift of the waterfall lip. From the point cloud obtained by TLS measurement, a digital elevation model on a vertical plane was generated, and cross-sectional profiles were extracted. A distinct 5- to 10-m depression was found at the bottom of the upper andesite layer of the waterfall cliff, which appears to have been formed by freeze-thaw and wet-dry weathering following the upstream shift of the surface water drop. Stability analysis of the waterfall cliff with an undercutting notch indicates that the igneous rock composing the cliff is sufficiently strong to maintain its current overhanging shape and that catastrophic collapse of the entire waterfall face rarely occurs. Following the formation of the depression, the upper cliff face appears to have been gradually eroded by gravitational collapses of relatively small blocks bounded by columnar and platy joints.
Cite this paper: Y. Hayakawa, "Stability Analysis of Cliff Face around Kegon Falls in Nikko, Eastern Japan: An Implication to Its Erosional Mechanisms," International Journal of Geosciences, Vol. 4 No. 6, 2013, pp. 8-16. doi: 10.4236/ijg.2013.46A2002.

[1]   O. D. von Engeln, “A Particular Case of Knickpunkte,” Annals of the Association of American Geographers, Vol. 30, No. 4, 1940, pp. 268-271,281-284. doi:10.2307/2560885

[2]   R. W. Young, “Waterfalls: Form and Process,” Zeitschriftfür Geomorphologie NF Supplementband, Vol. 55, 1985, pp. 81-95.

[3]   S. S. Philbrick, “Horizontal Configuration and the Rate of Erosion of Niagara Falls,” Geological Society of America Bulletin, Vol. 81, No. 12, 1970, p. 3723. doi:10.1130/0016-7606(1970)81[3723:HCATRO]2.0.CO;2

[4]   R. M. Derricourt, “Retrogression Rate of the Victoria Falls and the Batoka Gorge,” Nature, Vol. 264, 1976, pp. 23-25. doi:10.1038/264023a0

[5]   B. Crosby and K. Whipple, “Knickpoint Initiation and Distribution within Fluvial Networks: 236 Waterfalls in the Waipaoa River, North Island, New Zealand,” Geomorphology, Vol. 82, No. 1-2, 2006, pp. 16-38. doi:10.1016/j.geomorph.2005.08.023

[6]   Y. S. Hayakawa, S. Yokoyama and Y. Matsukura, “Erosion Rates of Waterfalls in Post-Volcanic Fluvial Systems around Aso Volcano, Southwestern Japan,” Earth Surface Processes and Landforms, Vol. 33, No. 5, 2008, pp. 801-812. doi:10.1002/esp.1615

[7]   P. Bishop and G. Goldrick, “Morphology, Processes and Evolution of Two Waterfalls near Cowra, New South Wales,” Australian Geographer, Vol. 23, No. 2, 1992, pp. 116-121. doi:10.1080/00049189208703061

[8]   Z. Alexandrowicz, “Geologically Controlled Waterfall Types in the Outer Carpathians,” Geomorphology, Vol. 9, No. 2, 1994, pp. 155-165. doi:10.1016/0169-555X(94)90073-6

[9]   Y. Hayakawa and Y. Matsukura, “Recession Rates of Waterfalls in Boso Peninsula, Japan, and a Predictive Equation,” Earth Surface Processes and Landforms, Vol. 28, No. 6, 2003, pp. 675-684. doi:10.1002/esp.519

[10]   P. Bishop, T. B. Hoey, J. D. Jansen and I. L. Artza, “Knickpoint Recession Rate and Catchment Area: The Case of Uplifted Rivers in Eastern Scotland,” Earth Surface Processes and Landforms, Vol. 30, No. 6, 2005, pp. 767-778. doi:10.1002/esp.1191

[11]   T. W. Gardner, “Experimental Study of Knickpoint and Longitudinal Profile Evolution in Cohesive, Homogeneous Material,” Geological Society of America Bulletin, Vol. 94, No. 5, 1983, pp. 664-672. doi:10.1130/0016-7606(1983)94<664:ESOKAL>2.0.CO;2

[12]   A. Bigi, L. E. Hasbargen, A. Montanari and C. Paola, “Knickpoints and Hillslope Failures: Interactions in a Steady-State Experimental Landscape,” Geological Society of America Special Paper, Vol. 398, 2006, pp. 295-307.

[13]   K. L. Frankel, F. J. Pazzaglia and J. D. Vaughn, “Knickpoint Evolution in a Vertically Bedded Substrate, Upstream-Dipping Terraces, and Atlantic Slope Bedrock Channels,” Geological Society of America Bulletin, Vol. 119, No. 3-4, 2007, pp. 476-486. doi:10.1130/B25965.1

[14]   M. P. Lamb and W. E. Dietrich, “The Persistence of Waterfalls in Fractured Rock,” Geological Society of America Bulletin, Vol. 121, No. 7-8, 2009, pp. 1123-1134. doi:10.1130/B26482.1

[15]   A. D. Howard, W. E. Dietrich and M. A. Seidl, “Modeling Fluvial Erosion on Regional to Continental Scales,” Journal of Geophysical Research, Vol. 99, No. B7, 1994, pp. 13971-13986. doi:10.1029/94JB00744

[16]   J. D. Niemann, N. M. Gasparini, G. E. Tucker and R. L. Bras, “A Quantitative Evaluation of Playfair’s Law and Its Use in Testing Long-Term Stream Erosion Models,” Earth Surface Processes and Landforms, Vol. 26, No. 12, 2001, pp. 1317-1332. doi:10.1002/esp.272

[17]   M. M. Berlin and R. S. Anderson, “Modeling of Knickpoint Retreat on the Roan Plateau, Western Colorado,” Journal of Geophysical Research, Vol. 112, No. F3, 2007, pp. 1-16. doi:10.1029/2006JF000553

[18]   I. Haviv, Y. Enzel, K. X. Whipple, E. Zilberman, A. Matmon, J. Stone and K. L. Fifield, “Evolution of Vertical Knickpoints (Waterfalls) with Resistant Caprock: Insights from Numerical Modeling,” Journal of Geophysical Research, Vol. 115, No. F3, 2010, pp. 1-22. doi:10.1029/2008JF001187

[19]   G. K. Gilbert, “Rate of Recession of Niagara Falls,” U.S. Geological Survey Bulletin, Vol. 306, 1907, pp. 1-31.

[20]   G. Vastola, “Asymmetric Crack Propagation near Waterfall Cliff and Its Influence on the Waterfall Lip Shape,” EPL (Europhysics Letters), Vol. 96, No. 4, 2011, Article ID: 49002.

[21]   M. P. Lamb, A. D. Howard, W. E. Dietrich and J. T. Perron, “Formation of Amphitheater-Headed Valleys by Waterfall Erosion after Large-Scale Slumping on Hawai’i,” Geological Society of America Bulletin, Vol. 119, No. 7-8, 2007, pp. 805-822. doi:10.1130/B25986.1

[22]   Y. S. Hayakawa and Y. Matsukura, “Factors Influencing the Recession Rate of Niagara Falls since the 19th Century,” Geomorphology, Vol. 110, No. 3-4, 2009, pp. 212-216. doi:10.1016/j.geomorph.2009.04.011

[23]   Y. Hayakawa and Y. Matsukura, “Recession Rates of Kegon Falls in Nikko, Tochigi Prefecture, Japan,” Journal of Geography (Tokyo), Vol. 112, No. 4, 2003, pp. 521-530.

[24]   Tochigi Prefecture, “Report of the Government Subsidy Survey for Erosion Controls in Volcanoes,” Tochigi Prefecture, Utsunomiya, 2001.

[25]   G. L. Heritage and A. R. G. Large, “Laser Scanning for the Environmental Sciences,” Wiley-Blackwell, Chichester, 2009.

[26]   D. J. Milan, G. L. Heritage and D. Hetherington, “Application of a 3D Laser Scanner in the Assessment of Erosion and Deposition Volumes and Channel Change in a Proglacial River,” Earth Surface Processes and Landforms, Vol. 32, No. 11, 2007, pp. 1657-1674. doi:10.1002/esp.1592

[27]   N. J. Rosser, D. N. Petley, M. Lim, S. A. Dunning and R. J. Allison, “Terrestrial Laser Scanning for Monitoring the Process of Hard Rock Coastal Cliff Erosion,” Quarterly Journal of Engineering Geology and Hydrogeology, Vol. 38, No. 4, 2005, pp. 363-375. doi:10.1144/1470-9236/05-008

[28]   B. D. Collins and N. Sitar, “Processes of Coastal Bluff Erosion in Weakly Lithified Sands, Pacifica, California, USA,” Geomorphology, Vol. 97, No. 3-4, 2008, pp. 483-501. doi:10.1016/j.geomorph.2007.09.004

[29]   M. Sturzenegger, D. Stead and D. Elmo, “Terrestrial Remote Sensing-Based Estimation of Mean Trace Length, Trace Intensity and Block Size/Shape,” Engineering Geology, Vol. 119, No. 3-4, 2011, pp. 96-111. doi:10.1016/j.enggeo.2011.02.005

[30]   M. A. O’Neal and J. E. Pizzuto, “The Rates and Spatial Patterns of Annual Riverbank Erosion Revealed through Terrestrial Laser-Scanner Surveys of the South River, Virginia,” Earth Surface Processes and Landforms, Vol. 36, No. 5, 2011, pp. 695-701. doi:10.1002/esp.2098

[31]   T. A. Wasklewicz and T. Hattanji, “High-Resolution Analysis of Debris Flow-Induced Channel Changes in a Headwater Stream, Ashio Mountains, Japan,” The Professional Geographer, Vol. 61, No. 2, 2009, pp. 231-249. doi:10.1080/00330120902743225

[32]   A. Viero, G. Teza, M. Massironi, M. Jaboyedoff and A. Galgaro, “Laser Scanning-Based Recognition of Rotational Movements on a Deep Seated Gravitational Instability: The Cinque Torri Case (North-Eastern Italian Alps),” Geomorphology, Vol. 122, No. 1-2, 2010, pp. 191-204. doi:10.1016/j.geomorph.2010.06.014

[33]   T. Suzuki, M. Okuno and Y. Hayakawa, “Eruption History of Volcanoes in Nikko,” Geekan Chikyu, Vol. 16, 1994, pp. 215-220.

[34]   Y. Mino, “On the Kegon Water-Fall in Nikko, Tochigi Pref,” Miscellany of Reports for Celebrating Professor H. Fujimoto’s 60th Birthday, 1958, pp. 344-363.

[35]   S. P. Timoshenko and J. M. Gere, “Mechanics of Materials,” Van Nostrand Reinhold Co., New York, 1978.

[36]   C. R. Thorne and N. K. Tovey, “Stability of Composite River Banks,” Earth Surface Processes and Landforms, Vol. 6, No. 5, 1981, pp. 469-484. doi:10.1002/esp.3290060507

[37]   T. K. S. Abam, “Genesis of Channel Bank Overhangs in the Niger Delta and Analysis of Mechanisms of Failure,” Geomorphology, Vol. 18, No. 2, 1997, pp. 151-164. doi:10.1016/S0169-555X(96)00010-4

[38]   Y. Matsukura, “Cliff Instability in Pumice Flow Deposits Due to Notch Formation on the Asama Mountain Slope, Japan,” Zeitschrift fuer Geomorphologie, Vol. 32, 1988, pp. 129-141.

[39]   T. Kogure, H. Aoki, A. Maekado, T. Hirose and Y. Matsukura, “Effect of the Development of Notches and Tension Cracks on Instability of Limestone Coastal Cliffs in the Ryukyus, Japan,” Geomorphology, Vol. 80, No. 3-4, 2006, pp. 236-244. doi:10.1016/j.geomorph.2006.02.012

[40]   T. Sunamura, “Geomorphology of Rocky Coasts,” John Wiley & Sons, Chichester, 1992.