Coverage under flood insurance does not begin until 30 days after you purchase it, so don't wait until the creek starts to rise to call your insurance agent. Benefits of Flooding Floods have both beneficial and dangerous aspects. Humans are attracted to floodplains because floods deposit nutrient-rich topsoil, eroded from upstream, producing fertile land for agriculture. In Egypt, for example, floods and deposition of nutrient-rich sediment from the Nile have increased agricultural yields for perhaps 5000 years. Flooding is also beneficial to streams because it serves in both local and regional environmental balance, affecting water quality and aquatic life.
Floods also recharge ground water supplies.