Journal of Range and Watershed Managment

Comparative Study of the Hydraulic Thresholds of Gully Erosion Flow in Different Land Uses (Case Study: Ghasreshirin, Kermanshah, Iran)

Document Type : Research Paper

Authors

Khosro Shahbazi 1
ali salajagheh 2
mohammad jafari 2
hassan ahmadi 2
ali akbar nazari samani 3
mohammad khosro shahi 4

1 Assistant Professor, Forests and Rangelands Research Institute of Iran, ARREO

2 Professor, Faculty of Natural Resources, University of Tehran

3 Associate Professor, Faculty of Natural Resources, University of Tehran

4 Associate Professor, Forests and Rangelands Research Institute of Iran, AREEO.

https://doi.org/10.22059/jrwm.2017.61191
Abstract
Negative impacts of gully erosion in marl areas are severe due to improper landuse practices such as irrigation, tillage, overgrazing and degradation of vegetation cover.  The objective of this research was to evaluate hydraulic flow thresholds of gully erosion in the agriculture (AG), fair rangeland (FR) and poor rangeland (PR) areas in the Qasre-shirin, Kermanshah, Iran. Nine flumes were performed in the field to determine the critical values of hydraulic parameters including flow discharge, velocity, Froude and Reynolds numbers, Darsi resistance coefficient, shear tension, head-cut dimensions as well as vegetation cover. Results showed that respective critical value of discharge as the gulling thresholds for AG,FR and PR was 1.53, 12.0 and 4.49 li/s indicating significantly higher (p<0.05%) in the FR due to  higher vegetation cover. In addition, there were no significant differences for flow disturbance based on Froude number, while the respective value of Rinuldze number in the AG, FR and WR were obtained 3113, 26092 and 9525 significantly higher in the FR. Furthermore, the critical level of shear tension for gully formation in the AG, FR and WR were found 12.12, 14.01 and 9.28 Nm-2, respectively showing significant differences among them. Finally, it is concluded that hydraulic flow parameters as the gully triggering are strongly affected by vegetation cover through landue practices so that higher plant cover in the FR was the key factor resulting in significant enhancement of gully.  

Keywords

Gully thresholds
Gasreshirin Region
hydraulic flow
Landuse
shear tension
Journal of Range and Watershed Managment
Volume 69, Issue 4
Winter 2017
Pages 931-947

  • Receive Date 22 May 2016
  • Revise Date 06 March 2017
  • Accept Date 27 March 2017
  • Publish Date 19 February 2017

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