Developing Empirical Relationship between Interrill Erosion, Rainfall Intensity, Slope Gradient and Soil Types in Highlands of Salale, Ethiopia

Developing Empirical Relationship between Interrill Erosion, Rainfall Intensity, Slope Gradient and Soil Types in Highlands of Salale, Ethiopia

Habtamu Adenew Weletu* Faculty of Resource Management, Economics, Wollega University, P.O. Box: 395, Nekemte, Ethiopia: Developing Empirical Relationship between Interrill Erosion, Rainfall Intensity, Slope Gradient and Soil Types in Highlands of Salale, Ethiopia. In: Science, Technology and Arts Research Journal, 5 (1), pp. 51-60, 2016, ISSN: 2226-7522 (Print) and 2305-3372 (Online).

Abstract

Abstract Article Information
In order to develop an empirical relationship for interrill erosion based on rainfall intensity,
slope steepness and soil types, an interrill erosion experiment was conducted using
laboratory rainfall simulator on three soil types (Vertisols, Cambisols and Leptosols) for the
highlands of North Shewa Zone of Oromia Region. From simulation work done using 450 x
320 x 100 mm erosion test pan; splashed soils, runoff and washed soils were collected at 5
minute interval for each 15 minutes simulation run at various combinations of design rainfall
intensities of 25.67, 52.14, 73.50, and 99.20 mmhr-1, slope steepness of 5, 20, 35, and 50%
and the three soil types. Runoff rate, splash and wash loss were measured to obtain a total
soil loss from the test pan. Different models relating interrill erosion with rainfall intensity and
runoff rate were considered and their coefficients and parameters were estimated. From the
models, those with highest prediction potential (R2) were selected to be incorporated into
models consisting soil properties and used to form six basic models of which three of them
had shown average R2 values of more than 0.95. Accordingly, five slope factor equations
were combined with the three selected models and thus 15 models were formed. Out of
these models, three of them had shown R2 > 0.90 and were further compared with each other
using the graph plotted for observed versus predicted interrill erosion. This showed that
model incorporating rainfall intensity, runoff rate, median soil particle diameter, % clay and
quadratic form of slope factor carried higher prediction potential than the other two models
and selected as the final model for predicting interrill erosion. As this model incorporates
more factors than those previously developed models, it ensures more accurate estimation
of interrill erosion.
Article History:
Received : 16-01-2016
Revised : 19-03-2016
Accepted : 22-03-2016
Keywords:
Interrill erosion
Empirical equations
Erosion models
*Corresponding Author:
Habtamu Adenew
E-mail:
sinanhaw29@gmail.com

BibTeX (Download)

@article{v5.i1.82016,
title = {Developing Empirical Relationship between Interrill Erosion, Rainfall Intensity, Slope Gradient and Soil Types in Highlands of Salale, Ethiopia},
author = {Habtamu Adenew Weletu*
Faculty of Resource Management and Economics, Wollega University, P.O. Box: 395, Nekemte, Ethiopia},
url = {https://starjournal.org/170065-article-text-437157-1-10-20180420/},
doi = {http://dx.doi.org/10.4314/star.v5i1.8},
issn = {2226-7522 (Print) and 2305-3372 (Online)},
year  = {2016},
date = {2016-03-29},
journal = {Science, Technology and Arts Research Journal},
volume = {5},
number = {1},
pages = {51-60},
abstract = {Abstract Article Information
In order to develop an empirical relationship for interrill erosion based on rainfall intensity,
slope steepness and soil types, an interrill erosion experiment was conducted using
laboratory rainfall simulator on three soil types (Vertisols, Cambisols and Leptosols) for the
highlands of North Shewa Zone of Oromia Region. From simulation work done using 450 x
320 x 100 mm erosion test pan; splashed soils, runoff and washed soils were collected at 5
minute interval for each 15 minutes simulation run at various combinations of design rainfall
intensities of 25.67, 52.14, 73.50, and 99.20 mmhr-1, slope steepness of 5, 20, 35, and 50%
and the three soil types. Runoff rate, splash and wash loss were measured to obtain a total
soil loss from the test pan. Different models relating interrill erosion with rainfall intensity and
runoff rate were considered and their coefficients and parameters were estimated. From the
models, those with highest prediction potential (R2) were selected to be incorporated into
models consisting soil properties and used to form six basic models of which three of them
had shown average R2 values of more than 0.95. Accordingly, five slope factor equations
were combined with the three selected models and thus 15 models were formed. Out of
these models, three of them had shown R2 > 0.90 and were further compared with each other
using the graph plotted for observed versus predicted interrill erosion. This showed that
model incorporating rainfall intensity, runoff rate, median soil particle diameter, % clay and
quadratic form of slope factor carried higher prediction potential than the other two models
and selected as the final model for predicting interrill erosion. As this model incorporates
more factors than those previously developed models, it ensures more accurate estimation
of interrill erosion.
Article History:
Received : 16-01-2016
Revised : 19-03-2016
Accepted : 22-03-2016
Keywords:
Interrill erosion
Empirical equations
Erosion models
*Corresponding Author:
Habtamu Adenew
E-mail:
sinanhaw29@gmail.com},
keywords = {STAR},
pubstate = {published},
tppubtype = {article}
}

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