Alluvial plains are flat, fertile areas formed by the deposition of sediment from rivers and streams. These plains are created when water flows over land, carrying soil and minerals that settle in low-lying regions. This process results in rich soil, making alluvial plains ideal for agriculture and supporting diverse ecosystems. Typically found near riverbanks, alluvial plains can vary in size and shape. They often experience seasonal flooding, which replenishes nutrients in the soil. Important examples of alluvial plains include the Indus River Plain in Pakistan and the Mississippi River Delta in the United States.