IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
Log On
About IAHRDirectoryCommitteesMy IAHRNews & JournalseLibraryeShopEventsJoin IAHRWorld CongressDonate
spacer.gif
spacer.gif eLibrary
spacer.gif eLibrary
You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Water resources and hydroinformatics : Effect of kinetic energy-intensity relationships and 0.5-h maximum intensity estimation methods on r...
Effect of kinetic energy-intensity relationships and 0.5-h maximum intensity estimation methods on rainfall erosivity
Author : GABRIEL P. LOBO(1), CARLOS A. BONILLA(1)
ABSTRACT
This paper analyses and compares rainfall erosivity values computed with five different kinetic energy-intensity (KE-I)
relationships using 0.5-h and 1-h maximum rainfall intensities (I30 and I60, respectively). Three exponential, a logarithmic
and a linear KE-I relationships were used to compute rainfall erosivity from pluviographic records of 30 sites located in
Central Chile. A total of 415 years of data were analyzed and more than 18,000 storms were identified. The results
showed that, among the exponential equations, the McGregor relationship yielded statistically equal erosivity results with
the Van Dijk and the Brown and Foster relationships. However, when comparing the Van Dijk and the Brown and Foster
relationships, significant erosivity differences were found, showing that the exponential equation is highly sensitive to
changes in its regression parameters and therefore site-specific. Among all the relationships, the Wischmeyer and Smith
logarithmic equation yielded the largest erosivity estimates. This equation provided slightly larger, but statistically equal
erosivity estimates than the McGregor and the Van Dijk relationships. However, the logarithmic relationship provided
statistically different erosivity estimates than the Brown and Foster relationship. An average difference of 36% was
observed between the erosivity estimates of these equations for every site. The linear relationship proposed by Hudson
yielded statistically different erosivity values to the rest of the equations. This equation provided erosivity estimates that
were, in average three times smaller than those predicted with the logarithmic equation. On the other hand, regardless of
the KE-I relationship and the site, computing erosivity using the I60 provided erosivity estimates that were 10% smaller
than those obtained using the I30. This is explained because the I60 was in average 10% smaller than I30 in the study sites.
Because erosivity is defined as the kinetic energy of the storms multiplied by their respective I30, a 10% variation in the I30
accounts for a 10% change in erosivity. Thus, the differences in erosivity reported among the KE-I relationships are
independent of the I30 estimation method. Finally, because the rainfall erosivity estimates in the study sites were highly
affected by the type of KE-I relationship, these results demonstrate that selecting an appropriate KE-I relationship is
crucial for accurate erosivity estimations. These differences were augmented because of the typically low rainfall
intensities at the study sites. Under this condition the KE-I relationships show the largest differences among them.
However, with higher rainfall intensities all the KE-I relationships provide similar kinetic energy estimates, making the KE-I
relationship selection less important than the use of a reliable I30 value for computing rainfall erosivity.
File Size : 653,348 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Water resources and hydroinformatics
Date Published : 18/08/2015
Download Now