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Application of an S‐shaped curve model to the temporal development of tafoni of salt‐weathering origin
Author(s) -
Sunamura Tsuguo,
Aoki Hisashi
Publication year - 2011
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.2175
Subject(s) - splash , weathering , geology , mode (computer interface) , salt lake , salt (chemistry) , geomorphology , hydrology (agriculture) , environmental science , atmospheric sciences , meteorology , physics , chemistry , geotechnical engineering , computer science , operating system , structural basin
To describe temporal change in tafone development, an S‐shaped curve equation is proposed: Z = Z c [1 − ( n + 1) exp (− β t ) + n exp (− (1 + 1/ n ) β t )] , where Z is observed tafone depth, Z c is ultimate tafone depth, t is time, and n and β are constants. The applicability of this model is examined using tafone data selected from seven sites, which are categorized into three different salt‐weathering environments: a spray/splash‐dominant (occasionally wave‐affected) supra‐tidal zone, aerosol‐affected coastal regions, and inland desert areas. The results indicate that the equation can well describe tafone development in each of these environments. An investigation based on the values of n and β , determined through a best fit of the equation to the data, suggests that n characterizes site‐specific environmental conditions and β reflects the magnitude of factors controlling the recession mechanism of tafone surfaces. It is found that (1) the maximum rate of tafone growth dramatically decreases from supra‐tidal, through coastal, to desert environments, and (2) the growing mode of tafoni is different depending on the environmental settings. The erosional force to facilitate the development of tafoni at supra‐tidal sites is estimated to be about 400 times greater than that in the general coastal area. Copyright © 2011 John Wiley & Sons, Ltd.