Slopes

This model is mostly consistent with the land use history of riverside ave and the slides that have happened over the last century. The calculations of this model show that this slope could slide in very similar conditions to that which we see occurring on the slope. In the decades before human changes on the slope, this slope was likely quite stable, as many transport limited slopes are. There was likely a robust forest growing on the slope, stabilizing the material with root cohesion and a thick layer of well consolidated soil. After deforestation, the slope is inherently more prone to sliding as roots rot and before new trees grow. After deforestation, dumping of unconsolidated material and disruption of drainage systems, slopes were primed to slide when hydrologic events, such as large storms saturate a slope and decrease the factor of safety to a dangerous point.

This recent slide was partially caused by the dumping of new material. This had several impacts: first, it increased the angle of the slope and second, it was very unconsolidated material with a very low resistance to shear stress. When the saturation of the slope increased, there was not enough resistance to the shear stress to keep the slope in place and a slide occurred. This slide came after several slides in the past indicating that this slope already has a low factor of safety and the added instability in conjunction with heavy rain lead to an unsurprising slide.