Geomorphic threshold conditions for gully erosion in Southwestern Iran (Boushehr - Samal watershed)

A SAMANI, H AHMADI, M JAFARI, Guy Boggs, J GHODDOUSI, A MALEKIAN

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    Globally, a large amount of research has been dedicated to furthering our understanding of the factors and mechanisms affecting gully erosion. However, despite the importance of gully erosion in arid and semi arid regions of Iran there has been no comprehensive study of the geomorphic threshold conditions and factors influencing gully initiation. The aim of this article is to investigate the gullying processes and threshold conditions of permanent gullies in an arid region of Iran based upon examination of the slope-area (S = ?A-?) relationship. The data were collected through field and laboratory studies as well as Digital Elevation Model (DEM) analyses. In total, 97 active headcuts were identified across the three study sites and classified based on dominant initiation process including piping, landsliding and overland flow. Soil properties, including EC, SAR and soil texture, as well as landuse practices were found to be the major factors initiating piping and bank gullies. All gullies initiated by landsliding and seepage processes were found to be located in steep areas (28-40% slope) with their distribution further influenced by the lithology and presence of a cohesionless sand layer within the soil profile. An inverse relationship between upslope area (A) and local slope (S), in which the ? and ? coefficients varied, was further investigated based on the dominant gullying process and land use. Gullies occurring in the rangelands that were dominated by overland flow had the strongest relationship while landsliding dominated gullies did not have a statistically significant S-A relationship. In comparison to theoretical and literature based relationships for gully initiation, relatively low values for ? were obtained (-0.182 to -0.266), possibly influenced by the presence of seepage and subsurface processes in many gullies. However, this is consistent with other studies in arid regions and may reflect greater potential for gullying in arid zones due to low vegetation cover and high variation in rainfall. In addition, the soil attributes together with land use practices influenced gully initiation thresholds. Application of the solved S-A relation for predicting vulnerable areas to gullying indicates that it is possible to predict the location of gullies with an acceptable level of accuracy; however other environmental factors should be integrated with the S-A relationship to more accurately identify the location of permanent gullies in arid regions. � 2009 Elsevier Ltd.
    Original languageEnglish
    Pages (from-to)180-189
    Number of pages10
    JournalJournal of Asian Earth Sciences
    Volume35
    Issue number2
    Publication statusPublished - 2009

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    gully erosion
    gully
    watershed
    arid region
    piping
    overland flow
    seepage
    land use
    soil texture
    semiarid region
    rangeland
    vegetation cover
    digital elevation model
    soil profile
    soil property
    lithology
    synthetic aperture radar
    environmental factor

    Cite this

    SAMANI, A., AHMADI, H., JAFARI, M., Boggs, G., GHODDOUSI, J., & MALEKIAN, A. (2009). Geomorphic threshold conditions for gully erosion in Southwestern Iran (Boushehr - Samal watershed). Journal of Asian Earth Sciences, 35(2), 180-189.
    SAMANI, A ; AHMADI, H ; JAFARI, M ; Boggs, Guy ; GHODDOUSI, J ; MALEKIAN, A. / Geomorphic threshold conditions for gully erosion in Southwestern Iran (Boushehr - Samal watershed). In: Journal of Asian Earth Sciences. 2009 ; Vol. 35, No. 2. pp. 180-189.
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    title = "Geomorphic threshold conditions for gully erosion in Southwestern Iran (Boushehr - Samal watershed)",
    abstract = "Globally, a large amount of research has been dedicated to furthering our understanding of the factors and mechanisms affecting gully erosion. However, despite the importance of gully erosion in arid and semi arid regions of Iran there has been no comprehensive study of the geomorphic threshold conditions and factors influencing gully initiation. The aim of this article is to investigate the gullying processes and threshold conditions of permanent gullies in an arid region of Iran based upon examination of the slope-area (S = ?A-?) relationship. The data were collected through field and laboratory studies as well as Digital Elevation Model (DEM) analyses. In total, 97 active headcuts were identified across the three study sites and classified based on dominant initiation process including piping, landsliding and overland flow. Soil properties, including EC, SAR and soil texture, as well as landuse practices were found to be the major factors initiating piping and bank gullies. All gullies initiated by landsliding and seepage processes were found to be located in steep areas (28-40{\%} slope) with their distribution further influenced by the lithology and presence of a cohesionless sand layer within the soil profile. An inverse relationship between upslope area (A) and local slope (S), in which the ? and ? coefficients varied, was further investigated based on the dominant gullying process and land use. Gullies occurring in the rangelands that were dominated by overland flow had the strongest relationship while landsliding dominated gullies did not have a statistically significant S-A relationship. In comparison to theoretical and literature based relationships for gully initiation, relatively low values for ? were obtained (-0.182 to -0.266), possibly influenced by the presence of seepage and subsurface processes in many gullies. However, this is consistent with other studies in arid regions and may reflect greater potential for gullying in arid zones due to low vegetation cover and high variation in rainfall. In addition, the soil attributes together with land use practices influenced gully initiation thresholds. Application of the solved S-A relation for predicting vulnerable areas to gullying indicates that it is possible to predict the location of gullies with an acceptable level of accuracy; however other environmental factors should be integrated with the S-A relationship to more accurately identify the location of permanent gullies in arid regions. � 2009 Elsevier Ltd.",
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    author = "A SAMANI and H AHMADI and M JAFARI and Guy Boggs and J GHODDOUSI and A MALEKIAN",
    year = "2009",
    language = "English",
    volume = "35",
    pages = "180--189",
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    SAMANI, A, AHMADI, H, JAFARI, M, Boggs, G, GHODDOUSI, J & MALEKIAN, A 2009, 'Geomorphic threshold conditions for gully erosion in Southwestern Iran (Boushehr - Samal watershed)', Journal of Asian Earth Sciences, vol. 35, no. 2, pp. 180-189.

    Geomorphic threshold conditions for gully erosion in Southwestern Iran (Boushehr - Samal watershed). / SAMANI, A; AHMADI, H; JAFARI, M; Boggs, Guy; GHODDOUSI, J; MALEKIAN, A.

    In: Journal of Asian Earth Sciences, Vol. 35, No. 2, 2009, p. 180-189.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

    T1 - Geomorphic threshold conditions for gully erosion in Southwestern Iran (Boushehr - Samal watershed)

    AU - SAMANI, A

    AU - AHMADI, H

    AU - JAFARI, M

    AU - Boggs, Guy

    AU - GHODDOUSI, J

    AU - MALEKIAN, A

    PY - 2009

    Y1 - 2009

    N2 - Globally, a large amount of research has been dedicated to furthering our understanding of the factors and mechanisms affecting gully erosion. However, despite the importance of gully erosion in arid and semi arid regions of Iran there has been no comprehensive study of the geomorphic threshold conditions and factors influencing gully initiation. The aim of this article is to investigate the gullying processes and threshold conditions of permanent gullies in an arid region of Iran based upon examination of the slope-area (S = ?A-?) relationship. The data were collected through field and laboratory studies as well as Digital Elevation Model (DEM) analyses. In total, 97 active headcuts were identified across the three study sites and classified based on dominant initiation process including piping, landsliding and overland flow. Soil properties, including EC, SAR and soil texture, as well as landuse practices were found to be the major factors initiating piping and bank gullies. All gullies initiated by landsliding and seepage processes were found to be located in steep areas (28-40% slope) with their distribution further influenced by the lithology and presence of a cohesionless sand layer within the soil profile. An inverse relationship between upslope area (A) and local slope (S), in which the ? and ? coefficients varied, was further investigated based on the dominant gullying process and land use. Gullies occurring in the rangelands that were dominated by overland flow had the strongest relationship while landsliding dominated gullies did not have a statistically significant S-A relationship. In comparison to theoretical and literature based relationships for gully initiation, relatively low values for ? were obtained (-0.182 to -0.266), possibly influenced by the presence of seepage and subsurface processes in many gullies. However, this is consistent with other studies in arid regions and may reflect greater potential for gullying in arid zones due to low vegetation cover and high variation in rainfall. In addition, the soil attributes together with land use practices influenced gully initiation thresholds. Application of the solved S-A relation for predicting vulnerable areas to gullying indicates that it is possible to predict the location of gullies with an acceptable level of accuracy; however other environmental factors should be integrated with the S-A relationship to more accurately identify the location of permanent gullies in arid regions. � 2009 Elsevier Ltd.

    AB - Globally, a large amount of research has been dedicated to furthering our understanding of the factors and mechanisms affecting gully erosion. However, despite the importance of gully erosion in arid and semi arid regions of Iran there has been no comprehensive study of the geomorphic threshold conditions and factors influencing gully initiation. The aim of this article is to investigate the gullying processes and threshold conditions of permanent gullies in an arid region of Iran based upon examination of the slope-area (S = ?A-?) relationship. The data were collected through field and laboratory studies as well as Digital Elevation Model (DEM) analyses. In total, 97 active headcuts were identified across the three study sites and classified based on dominant initiation process including piping, landsliding and overland flow. Soil properties, including EC, SAR and soil texture, as well as landuse practices were found to be the major factors initiating piping and bank gullies. All gullies initiated by landsliding and seepage processes were found to be located in steep areas (28-40% slope) with their distribution further influenced by the lithology and presence of a cohesionless sand layer within the soil profile. An inverse relationship between upslope area (A) and local slope (S), in which the ? and ? coefficients varied, was further investigated based on the dominant gullying process and land use. Gullies occurring in the rangelands that were dominated by overland flow had the strongest relationship while landsliding dominated gullies did not have a statistically significant S-A relationship. In comparison to theoretical and literature based relationships for gully initiation, relatively low values for ? were obtained (-0.182 to -0.266), possibly influenced by the presence of seepage and subsurface processes in many gullies. However, this is consistent with other studies in arid regions and may reflect greater potential for gullying in arid zones due to low vegetation cover and high variation in rainfall. In addition, the soil attributes together with land use practices influenced gully initiation thresholds. Application of the solved S-A relation for predicting vulnerable areas to gullying indicates that it is possible to predict the location of gullies with an acceptable level of accuracy; however other environmental factors should be integrated with the S-A relationship to more accurately identify the location of permanent gullies in arid regions. � 2009 Elsevier Ltd.

    KW - arid region

    KW - cohesionless soil

    KW - digital elevation model

    KW - geomorphology

    KW - gully erosion

    KW - land use

    KW - landslide

    KW - semiarid region

    KW - synthetic aperture radar

    KW - topography

    KW - vegetation cover

    KW - Asia

    KW - Eurasia

    KW - Iran

    KW - Middle East

    M3 - Article

    VL - 35

    SP - 180

    EP - 189

    JO - Journal of Asian Earth Sciences

    JF - Journal of Asian Earth Sciences

    SN - 1367-9120

    IS - 2

    ER -

    SAMANI A, AHMADI H, JAFARI M, Boggs G, GHODDOUSI J, MALEKIAN A. Geomorphic threshold conditions for gully erosion in Southwestern Iran (Boushehr - Samal watershed). Journal of Asian Earth Sciences. 2009;35(2):180-189.