BLUFF EROSION

One of the main problems with the landscape of Concordia University is it is located directly beside a receding bluff. The bluff is receding at  nearly 4 cm per year and has cost the university about 5 acres of land since the early 1980's. Bluff erosion is caused by a majority of factors. The  five important ones to take into consideration are wave surges, surface runoff, groundwater, freezing and thawing, and finally wind.

    1) Wave Surges

     Wave surges are a result of heavy rainstorms increasing the amount of energy carried by ways. This extra power attacks the base of the bluff and erodes the sediment. The constant bombardmnet of waves on the bluff thus causes the loose sediment to be carried away and leaving the bluff unstable

    2) Surface Runoff

    The water that flows down the bluff after intense rainfall carries with it all the loose topsoil. Things that could infulence the amount of runoff experienced include are amount of vegetation and types of soil.

    3) Groundwater
  
    The power of groundwater  can be sometimes more devastating than that of waves craashing at the foot of the bluff. As the groundwater moves through the soil, it saturates it and subsequently decreases the the forces that bond the soil together. This decreased causes the soil to become weak and unstable and has a tendency to want to slump downward. If enough soil slumps, large landslides could occur which provides safetey concerns for everyone in the area.

    4) Freeze and Thaw
 
    In cold weathers such as Wisconsin, the water goes through a periodic cycle of freezing and thawing. When the water freezes, it expands and pushes the soil apart, This causes landslides similar to those caused by groundwater. When the water melts, it saturates it and reduces the bonding of the soil or runs off and carries with it all the loose topsoil.

    5) Wind

    Wind plays an important factor in many different aspects relating to bluff erosion. The duration and strength of the wind has a direct effect on the amount of power gernarted by the waves crashing onto the land. Wind also can move loose sediments away from the bluff similar to surface runoff. Finally, can transport ice that has been building up on the top of the water. The wind could push the ice to the base of the bluff and causes down cutting on the bluff which increases the rate of erosion.




 

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