ScienceExplanation.in on Instagram: "A dam completely transforms the natural shape and flow of a river. When a dam blocks the river, water begins to collect behind it and forms a huge reservoir — spreading out over valleys, lowlands, and even entire forests or villages. This still water drowns the old river path and creates a lake where a flowing river once existed. Downstream, the river becomes weaker and loses its natural flood cycles. Sediments that the river once carried freely now get trapp