How have humans impacted the process of deposition?

I assume by deposition you mean the settlement of eroded material.

Rocks are broken down into smaller fragments through the process of weathering. The weathered fragments are then transported to new locations by the process of erosion. When eroding agents are unable to carry weathered fragments any longer, they get deposited at a location. Over time, this deposition causes changes in the landform.

Human activities have affected the process of deposition in a number of ways. Water is a common carrier of weathered material and is also affected by deposition. The human formation of dams causes the artificial storage of river water and forces the water to release the sediments it was carrying. This results in the non-formation of deposits. Human activities (such as construction and development) also often increase the weathering of rocks, which results in more fragments being available for erosion and deposition. The provision of wind turbines could affect the normal wind flow, which could influence the transport distance of eroded particles and hence the location of their deposition. 

Hope this helps.