Fluvial (Riverine) Flood

Primary reference(s)

WMO, 2012. Definition number 543. International Glossary of Hydrology. WMO-No. 385. World Meteorological Organization (WMO). Accessed 16 April 2020.

Additional scientific description

Fluvial flooding occurs over a wide range of river and catchment systems. Floods in river valleys occur mostly on flood plains or wash lands as a result of flow exceeding the capacity of the stream channels and spilling over the natural banks or artificial embankments (Fernandez, 2015). Metrics and numeric limits Not identified.

Metrics and numeric limits

Not identified.

Examples of drivers, outcomes and risk management

Drivers of fluvial flood: Fluvial (riverine) flooding primarily results from an extended precipitation event that occurs at, or upstream from, the affected area. It can also occur when traditional flood-control structures, such as levees and dikes, are overtopped (NOAA, no date).

Outcomes and impacts of fluvial flood: Flooding of areas used for socio-economic activities produces a variety of negative impacts. The magnitude of adverse impacts depends on the vulnerability of the activities and population and the frequency, intensity and extent of flooding. Some of these factors include loss of lives and property, loss of livelihoods, decreased purchasing power and production power, mass migration, psychosocial effects, hindering of economic growth and development, and political implications (APFM, no date).

Control and monitoring measures of fluvial flood: Floods are important components of the natural hydrological regime. They are a major source of water; they flush pollutants and sediment from river networks. It is also natural for rivers to overtop their banks with greater or lesser frequency and occupy their flood plains. As a result, floods can cause property damage and bring death and injury to many communities. While there is no evidence as yet that the frequency or magnitude of flooding has increased world-wide, flood-prone areas are becoming increasingly densely populated and thus more vulnerable. Consequently, a series of major flood disasters has occurred in recent years, with death and destruction being caused by such events on every continent (GWP, 2013).

There is a need for an approach to flood management that improves the functioning of the river basin as a whole, recognising that floods have beneficial impacts and can never be fully controlled. Such an approach seeks to maximize the net benefits from the use of floodplains and to minimise loss of life, subordinating flood loss reduction to the overall goal of maximising the efficient use of the floodplain (APFM, 2020).

Integrated Flood Management (IFM) is a process that promotes an integrated, rather than fragmented, approach to flood management. It integrates land and water resources development in a river basin, within the context of Integrated Resources Management, with a view to maximising the efficient use of floodplains and to minimising loss of life and property. IFM, like Integrated Water Resources Management, should encourage the participation of users, planners and policymakers at all levels. The approach should be open, transparent, inclusive and communicative; should require the decentralisation of decisionmaking; and should include public consultation and the involvement of stakeholders in planning and implementation. IFM calls for a paradigm shift from the traditional fragmented approach and encourages the efficient use of the resources of the river basin, employing strategies to maintain or augment the productivity of floodplains, while at the same time providing protective measures against losses due to flooding (APFM, no date).

Health impacts of floods including fluvial (riverine) floods: Floods are one of the most common hazards. The effects of flooding on health are extensive and significant, ranging from mortality and injuries resulting from trauma and drowning, to infectious diseases and mental health problems (acute and long-term). While some of these outcomes are relatively easy to track, ascertaining the human impact of floods is still weak. For example, it has been reported that two-thirds of deaths associated with flooding are from drowning, with the other third from physical trauma, heart attacks, electrocution, carbon monoxide poisoning and fire. Often, only immediate traumatic deaths from flooding are recorded (WHO, 2013).

Morbidity associated with floods is usually due to injuries, infections, chemical hazards and mental health effects (acute as well as delayed) (WHO, 2013). Hypothermia may also be a problem, particularly in children, if trapped in floodwaters for lengthy periods (WHO, no date). There may also be an increased risk of respiratory tract infections due to exposure (loss of shelter, exposure to flood waters and rain). Power cuts related to floods may disrupt water treatment and supply plants thereby increasing the risk of water-borne diseases, as well as affecting proper functioning of health facilities, including cold chain (WHO, no date). Floods can potentially increase the transmission of the following communicable diseases: water-borne diseases (such as typhoid fever, cholera, leptospirosis and hepatitis A) and vector-borne diseases (such as malaria, dengue and dengue haemorrhagic fever, yellow fever, and West Nile Fever) (WHO, no date).

The longer-term health effects associated with a flood are less easily identified. They include effects due to displacement, destruction of homes, delayed recovery and water shortages (WHO, 2013).