Some morphometric properties and erosion rates of gullies along a portion of the Manitoba Escarpment

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Young, R. V.
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Continuous gullies located on steep slopes along the Manitoba Escarpment were classified; the gully morphology was analyzed, and rates of gully erosion were calculated. Four of the gullies are classified as Stage 2 of gully development, and two gullies are classified as Stage 3. Five of the gullies are linear, and one gully is classified as parallel. The gully heads are classified as inclined-pointed, although one gully head could conceivably be classified as inclined-rounded, The gullies are in a youthful stage of development. Morphometric analysis revealed the gullies to be wider than they are deep, the north facing gully side is steeper than the south facing gully side, and the gully cross-sections are rectangular in shape. Gully cross-sections are rectangular in shape. Gully width and gully depth are related to the percentage of silt-clay within the surface material. The percentage of silt-clay is regarded as an indicator of the surface material's susceptibility to gully erosion. Much of the available energy for gully erosion was used to deepen rather than to widen the gully channel. Summer rainfall removed 23.8 times more material from the gullies than snowmelt runoff. Infrequent intense summer precipitation is identified as the major gully eroding agent. Soil freeze-thaw processes and the gully drainage basin snowmelt runoff had a tendency to add sediment to the gully channels during the 1974 spring snowmelt period. Those areas along the portion of the Manitoba Escarpment studied which are most susceptible to gully erosion are characterized as having steep slopes, large drainage basins, and containing surface materials having high percentages of silt-clay. It is recommended that revegetation and gully segregation methods be implemented to reduce and eventually stabilize gully erosion.