Gully erosion along the eastern shoreline of Lake Huron

Gully erosion along the shoreline of Lake Huron occurs within an environment of glacial clay tills, a humid temperate climate and anthropogenically modified drainage of the landscape. The aim of the research was to describe and examine the geomorphology of these gullies. The main objectives were: to develop a conceptual model applicable to the study area; to estimate and explain gully initiation; to examine gully growth between 1933 and 1992; to describe the morphology and vegetation patterns of the gullies; to examine erosion processes in one gully; and to discuss the implications for resource management strategies.; Gully and watershed dimensions and percent vegetation cover of a sample of forty-four gullies were measured from aerial photographs taken between 1930 and 1992. Types of erosion processes and patterns of vegetation cover were identified and sediment transport was measured with erosion pins in Borland Drain gully.; Initiation of most gullies occurred in the late nineteenth century because of the construction of drainage ditches following settlement of the region. Watershed area was the main factor controlling growth of gully area and length. Gullies with larger area and length had greater watershed areas and higher growth rates. Anthropogenic modification of the watershed resulted in elongated watersheds with a lack of surface drainage and tapered headcuts in most gullies. A high percentage of vegetation cover was associated with gullies with no evidence of erosion and reduced growth rates. Vegetation cover established first on more stable gully slopes near the mouth and on north-facing slopes. While many gullies have reduced growth rates and dense vegetation cover, subsurface flows and mass wasting can cause renewed gully erosion suggesting the gullies are self-perpetuating. Erosion losses from the slopes of Borland Drain gully were greatest from cliff faces and bare surfaces between late fall and late spring and minimal from vegetated surfaces. Resource management strategies are suggested and the conceptual model provides a framework for better understanding of the complex processes of gully erosion.