A dam significantly alters the topography of a river by transforming its natural flow and landscape! Upstream of the dam, water accumulates to form a reservoir, flooding the surrounding land and submerging existing features like valleys, forests, and sometimes entire settlements. This creates a flat, lake-like area where there was once a flowing river. Downstream, the river experiences reduced flow, which can lead to the narrowing of the riverbed and erosion of the channel due to decreased sedim