How Things Work on Instagram: "A dam changes river topography by interrupting natural flow, sediment transport, and erosion patterns. Upstream of the dam, water slows and spreads out, causing sediment that would normally move downstream to settle and build up, gradually raising the riverbed and forming a reservoir. Downstream, the released water is sediment-starved, so it erodes the riverbed and banks more aggressively, cutting the channel deeper and changing its shape. Flood peaks are reduced,