An understanding of slope stability is essential to knowing what care needs to go into a bluff. Unstable slopes can lead to large surface failure and also play a role in how fast coastlines can erode. There are multiple types of failures, and factors that cause failures, that occur on coastal slopes, and knowing the possibility of what is likely to happen will help to make decisions on improvements that can be made to mitigate these effects.
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Stable Slope CalculatorChanging the slope of a bluff is one major way to help reduce erosion. Click below to access a bluff slope calculator, and input current bluff height and angle, and stable bluff angle. Information will be provided on what the stable bluff angle is for the particular bluff soil type. The output will provide information on the location safe to build on.
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Bluff RemedationThe photos shown below are located at Concordia University in Mequon, WI. The first shows what the bluff looked like before remediation occurred. As seen from the photo there was severe erosion taking place, and to solve this problem the slope was decreased and protection was implemented to prevent further erosion.
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Sources of Bluff Erosion
Sources of Bluff Erosion
- Surface water runoff: large quantities of rainfall or snow melt leads to surface water collection and runoff, and this damages the integrity of the slope by affecting the soil particles.
- Wave attack and lake level changes: large storm systems can cause large waves and lake level rise which attack the base of a bluff causing slumping and landslides to occur.
- Groundwater seepage: similar to surface runoff groundwater seepage leads to bluff slumping mainly due to the presence of perched water tables.
- Wind erosion: the three largest impacts of wind are waves, the ability to move sediments, and by shoving ice against the shore which all make the bluff more susceptible to erosion.
- Freeze and thaw cycles: especially present in Wisconsin freeze and thaw cycles affect erosion because as water that is present in the soils pores freezes and expands it fractures the soil and rock causing the structural integrity to lack, and with the large quantities of snow melt in the spring adding weight which causes slope failure.