The Benefits of Flooding

Floodplain wildlife - Blue HeronFloods are natural phenomena; they play a role in the diversity, functionality and productivity of a number of ecosystems. When rivers overflow their banks due to melting snow or torrential rains, floods enrich surrounding land, leaving behind organic material and minerals in the sand, silt, and debris. Ancient Egyptians planned their planting and their lives around the summer flooding of the Nile, which leaves a thin, even coating of black mud along either side when it recedes, leaving the soil so enriched that fertilizer is unnecessary.

Floodplain vegetation and soils serve as water filters, intercepting surface water runoff before it reaches the lake, stream or river. This process aids in the removal of excess nutrients, pollutants and sediments from the water and helps reduce the need for costly cleanups and sediment removal.

Many species of fish and invertebrate have evolved lifecycles which require flood events to complete them. Flooding also maintains the channel structures of a river by transporting fine sediment onto floodplains. Floodplain vegetation provides important resting, feeding and nesting areas for many waterfowl species. Undisturbed floodplains have high natural biological diversity and productivity. River corridors also serve as migration routes for a number of species of birds.

Costs of Flooding

Although floods provide ecological benefits to the floodplain environment, when communities have been constructed on floodplains, flooding can cause property damage, destruction of roads and railways, and cost millions of dollars in lost wages and businesses. In addition to these physical costs victims of floods can experience mental stress and anxiety.

Flood DamagePhysical and Emotional Loss: Personal injury, loss of possessions and livelihood due to flooding can cause great distress and financial strain. However, loss from floods extends far beyond economic hardship. Apart from physical needs, individuals may feel anxiety, anger, helplessness, confusion, and guilt. Some may be experiencing profound grief. An important part of the emergency response to floods is addressing the mental health needs of flood victims, in addition to their physical needs.

Infrastructure and Property Loss: If water levels are high enough, water seeps into houses and buildings, washing through laundry rooms, tool sheds, garages, chemical storage closets, septic tanks and garbage receptacles. Apart for water damage to home contents, flood currents can exert such crushing pressures that they can topple buildings, wash roads away and severe railway links.

Lost Revenue: Flooding can disrupt communications, transportation and crop production. This disrupts businesses and industries, and results in lost revenue. Flooding in Canada costs millions of dollars each year in lost production, lost wages, and lost business.

Chemical Threat: Flood water can accumulate and carry chemicals, toxins and waste products that can filter through the water table for long periods of time. This creates a serious threat to water supplies. Flood victims must be extremely cautious about the water they drink, the food they eat, and how they bathe themselves.

Adapted from National Geographic's Floods and Dams< and Environment Canada's Freshwater Website <