Floodplain

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Parana River floodplain, at its confluence with the headstream of the Paranaiba (on the right) and the Verde River, near Panorama, Brazil Parana River Floodplain.jpg
Paraná River floodplain, at its confluence with the headstream of the Paranaíba (on the right) and the Verde River, near Panorama, Brazil
A floodplain after a one-in-10-year flood on the Isle of Wight Floodislewight.jpg
A floodplain after a one-in-10-year flood on the Isle of Wight
Gravel floodplain of a glacial river near the Snow Mountains in Alaska, 1902 Alaska Floodplain 1902.jpg
Gravel floodplain of a glacial river near the Snow Mountains in Alaska, 1902
The Laramie River meanders across its floodplain in Albany County, Wyoming, 1949 Laramie River floodplain 1949.jpg
The Laramie River meanders across its floodplain in Albany County, Wyoming, 1949
This aggradational floodplain of a small meandering stream in La Plata County, Colorado, is underlain by silt deposited above a dam formed by a terminal moraine left by the Wisconsin Glacier. Animas Valley CO 1903.jpg
This aggradational floodplain of a small meandering stream in La Plata County, Colorado, is underlain by silt deposited above a dam formed by a terminal moraine left by the Wisconsin Glacier.
Riparian vegetation on the floodplain of the Lynches River, close to Johnsonville, South Carolina. These tupelo and cypress trees show the high-water mark of flooding. Flood plain 7991.JPG
Riparian vegetation on the floodplain of the Lynches River, close to Johnsonville, South Carolina. These tupelo and cypress trees show the high-water mark of flooding.

A floodplain or flood plain or bottomlands [1] is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high discharge. [2] The soils usually consist of clays, silts, sands, and gravels deposited during floods. [3]

Contents

Because of regular flooding, floodplains frequently have high soil-fertility since nutrients are deposited with the flood waters. This can encourage farming; [4] some important agricultural regions, such as the Mississippi river basin and the Nile river basin, heavily exploit floodplains. Agricultural regions, as well as urban areas, have developed near or on floodplains to take advantage of the rich soil and freshwater. However, the risk of inundation has led to increasing efforts to control flooding.

Formation

Most floodplains are formed by deposition on the inside of river meanders and by overbank flow. [5]

Wherever the river meanders, the flowing water erodes the river bank on the outside of the meander, while sediments are simultaneously deposited in a point bar on the inside of the meander. This is described as lateral accretion since the deposition builds the point bar laterally into the river channel. Erosion on the outside of the meander usually closely balances deposition on the inside of the meander, so that the channel shifts in the direction of the meander without changing significantly in width. The point bar is built up to a level very close to that of the river banks. Significant net erosion of sediments occurs only when the meander cuts into higher ground. The overall effect is that, as the river meanders, it creates a level flood plain composed mostly of point bar deposits. The rate at which the channel shifts varies greatly, with reported rates ranging from too slow to measure to as much as 2,400 feet (730 m) per year for the Kosi River of India. [6]

Overbank flow takes place when the river is flooded with more water than can be accommodated by the river channel. Flow over the banks of the river deposits a thin veneer of sediments that is coarsest and thickest close to the channel. This is described as vertical accretion, since the deposits build upwards. In undisturbed river systems, overbank flow is a frequent occurrence, typically occurring every one to two years regardless of climate or topography. [7] Sedimentation rates for a three-day flood of the Meuse and Rhine Rivers in 1993 found average sedimentation rates in the floodplain of between 0.57 and 1.0 kg/m2. Higher rates were found on the levees (4 kg/m2 or more) and on low-lying areas (1.6 kg/m2). [8]

Sedimentation from the overbank flow is concentrated on natural levees, crevasse splays, and in wetlands and shallow lakes of flood basins. Natural levees are ridges along river banks that form from rapid deposition from the overbank flow. Most of the suspended sand is deposited on the levees, leaving the silt and clay sediments to be deposited as floodplain mud further from the river. Levees are typically built up enough to be relatively well-drained compared with nearby wetlands, and levees in non-arid climates are often heavily vegetated. [9]

Crevasses are formed by breakout events from the main river channel. The river bank fails and floodwaters scour a channel. Sediments from the crevasse spread out as delta-shaped deposits with numerous distributary channels. Crevasse formation is most common in sections of rivers where the river bed is accumulating sediments (aggrading). [10]

Repeated flooding eventually builds up an alluvial ridge, whose natural levees and abandoned meander loops may stand well above most of the floodplain. [11] The alluvial ridge is topped by a channel belt, formed by successive generations of channel migration and meander cutoff. At much longer intervals, the river may completely abandon the channel belt and begin building a new channel belt at another position on the floodplain. This process is called avulsion and takes place at intervals of 10–1000 years. Historical avulsions leading to catastrophic flooding include the 1855 Yellow River flood and the 2008 Kosi River flood. [12]

Floodplains can form around rivers of any kind or size. Even relatively straight stretches of river are found to be capable of producing floodplains. Mid-channel bars in braided rivers migrate downstream through processes resembling those in point bars of meandering rivers and can build up a floodplain. [13]

The quantity of sediments in a floodplain greatly exceeds the river load of sediments. Thus, floodplains are an important storage site for sediments during their transport from where they are generated to their ultimate depositional environment. [14]

When the rate at which the river is cutting downwards becomes great enough that overbank flows become infrequent, the river is said to have abandoned its floodplain, and portions of the abandoned floodplain may be preserved as fluvial terraces. [15]

Ecology

Floodplains support diverse and productive ecosystems. [16] [17] They are characterized by considerable variability in space and time, which in turn produces some of the most species-rich of ecosystems. [18] From the ecological perspective, the most distinctive aspect of floodplains is the flood pulse associated with annual floods, and so the floodplain ecosystem is defined as the part of the river valley that is regularly flooded and dried. [19]

Floods bring in detrital material rich in nutrients, and release nutrients from dry soil as it is flooded. The decomposition of terrestrial plants submerged by the floodwaters adds to the nutrient supply. The flooded littoral zone of the river (the zone closest to the river bank) provides an ideal environment for many aquatic species, so the spawning season for fish often coincides with the onset of flooding. Fish must grow quickly during the flood to survive the subsequent drop in water level. As the floodwaters recede, the littoral experiences blooms of microorganisms, while the banks of the river dry out and terrestrial plants germinate to stabilize the bank. [19]

A low-lying field in Achterwehr Germany inundated by overflow from a nearby waterway. Achterwehr (129456655).jpeg
A low-lying field in Achterwehr Germany inundated by overflow from a nearby waterway.

The biota of floodplains has high annual growth and mortality rates, which is advantageous for the rapid colonization of large areas of the floodplain. This allows them to take advantage of shifting floodplain geometry. [19] For example, floodplain [20] trees are fast-growing and tolerant of root disturbance. Opportunists (such as birds) are attracted to the rich food supply provided by the flood pulse. [16]

Floodplain ecosystems have distinct biozones. In Europe, as one moves away from the river, the successive plant communities are bank vegetation (usually annuals); sedge and reeds; willow shrubs; willow-poplar forest; oak-ash forest; and broadleaf forest. Human disturbance creates wet meadows that replace much of the original ecosystem. [21] The biozones reflect a soil moisture and oxygen gradient that in turn corresponds to a flooding frequency gradient. [22] The primeval floodplain forests of Europe were dominated by oak (60%) elm (20%) and hornbeam (13%), but human disturbance has shifted the makeup towards ash (49%) with maple increasing to 14% and oak decreasing to 25%. [17]

Semiarid floodplains have a much lower diversity of species, which are adapted to alternating drought and flood. Extreme drying can destroy the ability of the floodplain ecosystem to shift to a healthy wet phase when flooded. [23]

Floodplain forests constituted 1% of the landscape of Europe in the 1800s. Much of this has been cleared by human activity, though floodplain forests have been impacted less than other kinds of forests. This makes them important refugia for biodiversity. [17] [16] Human destruction of floodplain ecosystems is largely a result of flood control, [19] hydroelectric development (such as reservoirs), and conversion of floodplains to agriculture use. [17] Transportation and waste disposal also have detrimental effects. [19] The result is the fragmentation of these ecosystems, resulting in loss of populations and diversity [17] and endangering the remaining fragments of the ecosystem. [18] Flood control creates a sharper boundary between water and land than in undisturbed floodplains, reducing physical diversity. [19] Floodplain forests protect waterways from erosion and pollution and reduce the impact of floodwaters. [17]

The disturbance by humans of temperate floodplain ecosystems frustrates attempts to understand their natural behavior. Tropical rivers are less impacted by humans and provide models for temperate floodplain ecosystems, which are thought to share many of their ecological attributes. [19]

Flood control

Excluding famines and epidemics, some of the worst natural disasters in history [24] (measured by fatalities) have been river floods, particularly in the Yellow River in China – see list of deadliest floods. The worst of these, and the worst natural disaster (excluding famine and epidemics) was the 1931 China floods, estimated to have killed millions. This had been preceded by the 1887 Yellow River flood, which killed around one million people, and is the second-worst natural disaster in history.

The extent of floodplain inundation depends in part on the flood magnitude, defined by the return period.

In the United States, the Federal Emergency Management Agency (FEMA) manages the National Flood Insurance Program (NFIP). The NFIP offers insurance to properties located within a flood-prone area, as defined by the Flood Insurance Rate Map (FIRM), which depicts various flood risks for a community. The FIRM typically focuses on the delineation of the 100-year flood inundation area, also known within the NFIP as the Special Flood Hazard Area.

Where a detailed study of a waterway has been done, the 100-year floodplain will also include the floodway, the critical portion of the floodplain which includes the stream channel and any adjacent areas that must be kept free of encroachments that might block flood flows or restrict storage of flood waters. Another commonly encountered term is the Special Flood Hazard Area, which is any area subject to inundation by a 100-year flood. [25] A problem is that any alteration of the watershed upstream of the point in question can potentially affect the ability of the watershed to handle water, and thus potentially affects the levels of the periodic floods. A large shopping center and parking lot, for example, may raise the levels of 5-year, 100-year, and other floods, but the maps are rarely adjusted and are frequently rendered obsolete by subsequent development.

In order for a flood-prone property to qualify for government-subsidized insurance, a local community must adopt an ordinance that protects the floodway and requires that new residential structures built in Special Flood Hazard Areas be elevated to at least the level of the 100-year flood. Commercial structures can be elevated or floodproofed to or above this level. In some areas without detailed study information, structures may be required to be elevated to at least two feet above the surrounding grade. [26] Many State and local governments have, in addition, adopted floodplain construction regulations which are more restrictive than those mandated by the NFIP. The US government also sponsors flood hazard mitigation efforts to reduce flood impacts. California's Hazard Mitigation Program is one funding source for mitigation projects. A number of whole towns such as English, Indiana, have been completely relocated to remove them from the floodplain. Other smaller-scale mitigation efforts include acquiring and demolishing flood-prone buildings or flood-proofing them.

In some floodplains, such as the Inner Niger Delta of Mali, annual flooding events are a natural part of the local ecology and rural economy, allowing for the raising of crops through recessional agriculture. However, in Bangladesh, which occupies the Ganges Delta, the advantages provided by the richness of the alluvial soil of the floodplain are severely offset by frequent floods brought on by cyclones and annual monsoon rains. These extreme weather events cause severe economic disruption and loss of human life in the densely-populated region.

Flooding of Pampanga River floodplain after Typhoon Quinta, 2020 (view from Santa Rosa, Nueva Ecija bridge). Flooding of Pampanga River after Typhoon Quinta (Molave), Santa Rosa, Nueva Ecija.jpg
Flooding of Pampanga River floodplain after Typhoon Quinta, 2020 (view from Santa Rosa, Nueva Ecija bridge).

Floodplain Soils

Oxygen in Floodplain Soils

Floodplain soil composition is unique and varies widely based on microtopography. Floodplain forests have high topographic heterogeneity which creates variation in localized hydrologic conditions. [27] Soil moisture within the upper 30 cm of the soil profile also varies widely based on microtopography which affects oxygen availability. [28] [29] Floodplain soil stays aerated for long stretches of time in between flooding events, but during flooding, saturated soil can become oxygen-depleted if it stands stagnant for long enough. More soil oxygen is available at higher elevations farther from the river. Floodplain forests generally experience alternating periods of aerobic and anaerobic soil microbe activity which affects fine root development and desiccation. [30] [31] [32]

Phosphorus Cycling in Floodplain Soils

Floodplains have high buffering capacity for phosphorus to prevent nutrient loss to river outputs. [33] Phosphorus nutrient loading is a problem in freshwater systems. Much of the phosphorus in freshwater systems comes from municipal wastewater treatment plants and agricultural runoff. [34] Stream connectivity controls whether phosphorus cycling is mediated by floodplain sediments or by external processes. [34] Under conditions of stream connectivity, phosphorus is better able to be cycled, and sediments and nutrients are more readily retained. [35] Water in freshwater streams ends up in either short-term storage in plants or algae or long-term in sediments. [34] Wet/dry cycling within the floodplain has a big impact on phosphorus availability because it alters water level, redox state, pH, and physical properties of minerals. [34] Dry soils that were previously inundated have reduced availability of phosphorus and increased affinity for obtaining phosphorus. [36] Human floodplain alterations also impact the phosphorus cycle. [37] Particulate phosphorus and soluble reactive phosphorus (SRP) can contribute to algal blooms and toxicity in waterways when the nitrogen-to-phosphorus ratios are altered farther upstream. [38] In areas where the phosphorus load is primarily particulate phosphorus, like the Mississippi River, the most effective ways of removing phosphorus upstream are sedimentation, soil accretion, and burial. [39] In basins where SRP is the primary form of phosphorus, biological uptake in floodplain forests is the best way of removing nutrients. [38] Phosphorus can transform between SRP and particulate phosphorus depending on ambient conditions or processes like decomposition, biological uptake, redoximorphic release, and sedimentation and accretion. [40] In either phosphorus form, floodplain forests are beneficial as phosphorus sinks, and the human-caused disconnect between floodplains and rivers exacerbates the phosphorus overload. [41]

Environmental Pollutants in Floodplain Soils

Floodplain soils tend to be high in eco-pollutants, especially persistent organic pollutant (POP) deposition. [42] Proper understanding of the distribution of soil contaminants is difficult because of high variation in microtopography and soil texture within floodplains. [43]

See also

Related Research Articles

<span class="mw-page-title-main">Levee</span> Ridge or wall to hold back water

A levee, dike, dyke, embankment, floodbank, or stop bank is a structure used to keep the course of rivers from changing and to protect against flooding of the area adjoining the river or coast. It is usually earthen and often runs parallel to the course of a river in its floodplain or along low-lying coastlines.

<span class="mw-page-title-main">Wetland</span> Land area that is permanently, or seasonally saturated with water

A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently for years or decades or seasonally for a shorter periods. Flooding results in oxygen-free anoxic processes prevailing, especially in the soils. The primary factor that distinguishes wetlands from terrestrial land forms or water bodies is the characteristic vegetation of aquatic plants, adapted to the unique anoxic hydric soils. Wetlands are considered among the most biologically diverse of all ecosystems, serving as home to a wide range of plant and animal species. Methods for assessing wetland functions, wetland ecological health, and general wetland condition have been developed for many regions of the world. These methods have contributed to wetland conservation partly by raising public awareness of the functions some wetlands provide. Constructed wetlands are designed and built to treat municipal and industrial wastewater as well as to divert stormwater runoff. Constructed wetlands may also play a role in water-sensitive urban design.

<span class="mw-page-title-main">Tonlé Sap</span> Combined lake and river system in Cambodia

Tonlé Sap is a lake in the northwest of Cambodia. Belonging to the Mekong River system, Tonlé is the largest freshwater lake in Southeast Asia and one of the most diverse and productive ecosystems in the world. It has been designated as a Biosphere Reserve by UNESCO in 1997 due to its high biodiversity. In the 21st century, the lake and its surrounding ecosystems are under increasing pressure from deforestation, infrastructure development and climate change.

<span class="mw-page-title-main">Stream bed</span> Channel bottom of a stream, river, or creek

A streambed or stream bed is the bottom of a stream or river (bathymetry) and is confined within a channel, or the banks (bank of the waterway. Usually the bed does not contain terrestrial vegetation and instead supports different types of aquatic vegetation, depending on the type of streambed material and water velocity. Streambeds are what would be left once a stream is no longer in existence. The beds are usually well preserved even if they get buried because the banks and canyons made by the stream are typically hard, although soft sand and debris often fill the bed. Dry, buried streambeds can actually be underground water pockets. During times of rain, sandy streambeds can soak up and retain water, even during dry seasons, keeping the water table close enough to the surface to be obtainable by local people.

<span class="mw-page-title-main">Atchafalaya Basin</span> Largest wetland and swamp in the United States

The Atchafalaya Basin, or Atchafalaya Swamp, is the largest wetland and swamp in the United States. Located in south central Louisiana, it is a combination of wetlands and river delta area where the Atchafalaya River and the Gulf of Mexico converge. The river stretches from near Simmesport in the north through parts of eight parishes to the Morgan City southern area.

An overbank is an alluvial geological deposit consisting of sediment that has been deposited on the floodplain of a river or stream by flood waters that have broken through or overtopped the banks. The sediment is carried in suspension, and because it is carried outside of the main channel, away from faster flow, the sediment is typically fine-grained. An overbank deposit usually consists primarily of fine sand, silt and clay. Overbank deposits can be beneficial because they refresh valley soils.

<span class="mw-page-title-main">Crevasse splay</span> Sediment deposited on a floodplain by a stream which breaks its levees

A crevasse splay is a sedimentary fluvial deposit which forms when a stream breaks its natural or artificial levees and deposits sediment on a floodplain. A breach that forms a crevasse splay deposits sediments in similar pattern to an alluvial fan deposit. Once the levee has been breached the water flows out of its channel. As the water spreads onto the flood plain sediments will start to fall out of suspension as the water loses energy. The resulting deposition can create graded deposits similar to those found in Bouma sequences. In some cases crevasse splays can cause a river to abandon its old river channel, a process known as avulsion. Breaches that form a crevasse splay deposits occur most commonly on the outside banks of meanders where the water has the highest energy. Crevasse splay deposits can range in size. Larger deposits can be 6 m (20 ft) thick at the levee and spread 2 km (1.2 mi) wide, while smaller deposits may only be 1 cm (0.39 in) thick.

<span class="mw-page-title-main">Environmental impact of reservoirs</span>

The environmental impact of reservoirs comes under ever-increasing scrutiny as the global demand for water and energy increases and the number and size of reservoirs increases.

<span class="mw-page-title-main">River</span> Natural flowing watercourse

A river is a natural flowing watercourse, usually a freshwater stream, flowing on the Earth's land surface or inside caves towards another waterbody at a lower elevation, such as an ocean, sea, bay, lake, wetland, or another river. In some cases, a river flows into the ground or becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to by names such as creek, brook, and rivulet. There are no official definitions for these various generic terms for a watercourse as applied to geographic features, although in some countries or communities, a stream is customarily referred to by one of these names as determined by its size. Many names for small rivers are specific to geographic location; examples are "run" in some parts of the United States, "burn" in Scotland and Northeast England, and "beck" in Northern England. Sometimes a river is defined as being larger than a creek, but not always; the language is vague.

<span class="mw-page-title-main">Backswamp</span> Environment on a floodplain where deposits settle after a flood

In geology, a backswamp is a type of depositional environment commonly found in a floodplain. It is where deposits of fine silts and clays settle after a flood. These deposits create a marsh-like landscape that is often poorly drained and usually lower than the rest of the floodplain.

<span class="mw-page-title-main">Avulsion (river)</span> Rapid abandonment of a river channel and formation of a new channel

In sedimentary geology and fluvial geomorphology, avulsion is the rapid abandonment of a river channel and the formation of a new river channel. Avulsions occur as a result of channel slopes that are much less steep than the slope that the river could travel if it took a new course.

<span class="mw-page-title-main">Alluvial river</span> Type of river

An alluvial river is one in which the bed and banks are made up of mobile sediment and/or soil. Alluvial rivers are self-formed, meaning that their channels are shaped by the magnitude and frequency of the floods that they experience, and the ability of these floods to erode, deposit, and transport sediment. For this reason, alluvial rivers can assume a number of forms based on the properties of their banks; the flows they experience; the local riparian ecology; and the amount, size, and type of sediment that they carry.

<i>Igapó</i> Flooded Amazon forests in Brazil

Igapó is a word used in Brazil for blackwater-flooded forests in the Amazon biome. These forests and similar swamp forests are seasonally inundated with freshwater. They typically occur along the lower reaches of rivers and around freshwater lakes. Freshwater swamp forests are found in a range of climate zones, from boreal through temperate and subtropical to tropical. In the Amazon Basin of Brazil, a seasonally whitewater-flooded forest is known as a várzea, which is similar to igapó in many regards; the key difference between the two habitats is in the type of water that floods the forest.

<span class="mw-page-title-main">Riparian-zone restoration</span> Ecological restoration of river banks and floodplains

Riparian-zone restoration is the ecological restoration of riparian-zonehabitats of streams, rivers, springs, lakes, floodplains, and other hydrologic ecologies. A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the fifteen terrestrial biomes of the earth; the habitats of plant and animal communities along the margins and river banks are called riparian vegetation, characterized by aquatic plants and animals that favor them. Riparian zones are significant in ecology, environmental management, and civil engineering because of their role in soil conservation, their habitat biodiversity, and the influence they have on fauna and aquatic ecosystems, including grassland, woodland, wetland or sub-surface features such as water tables. In some regions the terms riparian woodland, riparian forest, riparian buffer zone, or riparian strip are used to characterize a riparian zone.

<span class="mw-page-title-main">Yazoo stream</span> Hydrologic term

A Yazoo stream is a geologic and hydrologic term for any tributary stream that runs parallel to, and within the floodplain of a larger river for considerable distance, before eventually joining it. This is especially the characteristic when such a stream is forced to flow along the base of the main river's natural levee. Where the two meet is known as a "belated confluence" or a "deferred junction". The name is derived from an exterminated Native American tribe, the Yazoo Indians. The Choctaw word is translated to "River of Death" because of the strong flows under its bank full stage.

<span class="mw-page-title-main">Flood pulse concept</span> Concept in river ecology and hydrology

The flood pulse concept explains how the periodic inundation and drought control the lateral exchange of water, nutrients and organisms between the main river channel and the connected floodplain. The annual flood pulse is the most important aspect and the most biologically productive feature of a river's ecosystem. describing the movement, distribution and quality of water in river ecosystems and the dynamic interaction in the transition zone between water and land. It contrasts with previous ecological theories which considered floods to be catastrophic events.

The Mississippi Alluvial Plain is a Level III ecoregion designated by the Environmental Protection Agency (EPA) in seven U.S. states, though predominantly in Arkansas, Louisiana, and Mississippi. It parallels the Mississippi River from the Midwestern United States to the Gulf of Mexico.

Vulnerable waters refer to geographically isolated wetlands (GIWs) and to ephemeral and intermittent streams. Ephemeral and intermittent streams are seasonally flowing and are located in headwater position. They are the outer and smallest stems of hydrological networks. Isolated wetlands are located outside floodplain and show poor surface connection to tributaries or floodplains. Geographically isolated wetlands encompass saturated depressions that are the result of fluvial, aeolian, glacial and/or coastal geomorphological processes. They may be natural landforms or the result of human interventions. Vulnerable waters represent the major proportion of river networks.

Legacy sediment (LS) is depositional bodies of sediment inherited from the increase of human activities since the Neolithic. These include a broad range of land use and land cover changes, such as agricultural clearance, lumbering and clearance of native vegetation, mining, road building, urbanization, as well as alterations brought to river systems in the form of dams and other engineering structures meant to control and regulate natural fluvial processes (erosion, deposition, lateral migration, meandering). The concept of LS is used in geomorphology, ecology, as well as in water quality and toxicological studies.

<span class="mw-page-title-main">Sedimentation enhancing strategy</span> Environmental management projects aiming to restore land-building processes in deltas

Sedimentation enhancing strategies are environmental management projects aiming to restore and facilitate land-building processes in deltas. Sediment availability and deposition are important because deltas naturally subside and therefore need sediment accumulation to maintain their elevation, particularly considering increasing rates of sea-level rise. Sedimentation enhancing strategies aim to increase sedimentation on the delta plain primarily by restoring the exchange of water and sediments between rivers and low-lying delta plains. Sedimentation enhancing strategies can be applied to encourage land elevation gain to offset sea-level rise. Interest in sedimentation enhancing strategies has recently increased due to their ability to raise land elevation, which is important for the long-term sustainability of deltas.

References

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  2. ↑ Goudie, A. S., 2004, Encyclopedia of Geomorphology, vol. 1. Routledge, New York. ISBN   0-415-32737-7
  3. ↑ Kovács, János (2013). "Flood Deposits". Encyclopedia of Natural Hazards. Encyclopedia of Earth Sciences Series. p. 325. doi:10.1007/978-1-4020-4399-4_137. ISBN   978-90-481-8699-0.
  4. ↑ Scott, James C. (22 August 2017). "The Domestication of Fire, Plants, Animals, and ... Us". Against the Grain: A Deep History of the Earliest States. New Haven: Yale University Press. p. 66. ISBN   978-0-3002-3168-7 . Retrieved 19 March 2023. The general problem with farming — especially plough agriculture — is that it involves so much intensive labor. One form of agriculture, however, eliminates most of this labor: 'flood-retreat' (also known as décrue or recession) agriculture. In flood-retreat agriculture, seeds are generally broadcast on the fertile silt deposited by an annual riverine flood.
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  15. ↑ Wolman & Leopold 1957, p. 105.
  16. 1 2 3 Kulhavy, Jiri; Cater, Matjaz. "Floodplain forest ecosystems". International Union of Forest Research Organizations. Retrieved 15 November 2021.
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  24. ↑ development, Jessica Karpilo holds a B. A. in Geography from the University of Denver She has written on the subjects of sustainable; Karpilo, maps our editorial process Jessica. "What Are the 10 Deadliest Disasters in World History?". ThoughtCo. Archived from the original on 2020-11-27. Retrieved 2020-11-30.
  25. ↑ "44 CFR 59.1 - Definitions". LII / Legal Information Institute. Archived from the original on 2017-08-29. Retrieved 2017-01-13.
  26. ↑ "44 CFR 60.3 - Flood plain management criteria for flood-prone areas". LII / Legal Information Institute. Archived from the original on 2017-08-29. Retrieved 2017-01-13.
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  30. ↑ Keeley, Jon E. (March 1979). "Population Differentiation along a Flood Frequency Gradient: Physiological Adaptations to Flooding in Nyssa sylvatica". Ecological Monographs. 49 (1): 89–108. Bibcode:1979EcoM...49...89K. doi:10.2307/1942574. ISSN   0012-9615. JSTOR   1942574.
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  32. ↑ Jones, Robert H.; Lockaby, B. Graeme; Somers, Greg L. (1996). "Effects of Microtopography and Disturbance on Fine-Root Dynamics in Wetland Forests of Low-Order Stream Floodplains". The American Midland Naturalist. 136 (1): 57–71. doi:10.2307/2426631. ISSN   0003-0031. JSTOR   2426631.
  33. ↑ Arenberg, Mary R.; Liang, Xinqiang; Arai, Yuji (2020-10-01). "Immobilization of agricultural phosphorus in temperate floodplain soils of Illinois, USA". Biogeochemistry. 150 (3): 257–278. Bibcode:2020Biogc.150..257A. doi:10.1007/s10533-020-00696-1. ISSN   1573-515X.
  34. 1 2 3 4 Schönbrunner, Iris M.; Preiner, Stefan; Hein, Thomas (August 2012). "Impact of drying and re-flooding of sediment on phosphorus dynamics of river-floodplain systems". Science of the Total Environment. 432 (10): 329–337. Bibcode:2012ScTEn.432..329S. doi:10.1016/j.scitotenv.2012.06.025. ISSN   0048-9697. PMC   3422535 . PMID   22750178.
  35. ↑ Noe, Gregory B.; Hupp, Cliff R.; Rybicki, Nancy B. (2013-01-01). "Hydrogeomorphology Influences Soil Nitrogen and Phosphorus Mineralization in Floodplain Wetlands". Ecosystems. 16 (1): 75–94. Bibcode:2013Ecosy..16...75N. doi:10.1007/s10021-012-9597-0. ISSN   1435-0629.
  36. ↑ Baldwin, D.S.; Mitchell, A.M. (September 2000). "The effects of drying and re-flooding on the sediment and soil nutrient dynamics of lowland river-floodplain systems: a synthesis". Regulated Rivers: Research & Management. 16 (5): 457–467. doi:10.1002/1099-1646(200009/10)16:5<457::AID-RRR597>3.0.CO;2-B. ISSN   0886-9375.
  37. ↑ Baldwin, D.S.; Mitchell, A.M. (September 2000). "The effects of drying and re-flooding on the sediment and soil nutrient dynamics of lowland river-floodplain systems: a synthesis". Regulated Rivers: Research & Management. 16 (5): 457–467. doi:10.1002/1099-1646(200009/10)16:5<457::AID-RRR597>3.0.CO;2-B. ISSN   0886-9375.
  38. 1 2 Jarvie, Helen P.; Johnson, Laura T.; Sharpley, Andrew N.; Smith, Douglas R.; Baker, David B.; Bruulsema, Tom W.; Confesor, Remegio (January 2017). "Increased Soluble Phosphorus Loads to Lake Erie: Unintended Consequences of Conservation Practices?". Journal of Environmental Quality. 46 (1): 123–132. Bibcode:2017JEnvQ..46..123J. doi:10.2134/jeq2016.07.0248. ISSN   0047-2425. PMID   28177409.
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  40. ↑ Hoffmann, Carl Christian; Kjaergaard, Charlotte; Uusi-Kämppä, Jaana; Hansen, Hans Christian Bruun; Kronvang, Brian (September 2009). "Phosphorus Retention in Riparian Buffers: Review of Their Efficiency". Journal of Environmental Quality. 38 (5): 1942–1955. Bibcode:2009JEnvQ..38.1942H. doi:10.2134/jeq2008.0087. ISSN   0047-2425.
  41. ↑ Pagano, T. C. (2014-07-17). "Evaluation of Mekong River commission operational flood forecasts, 2000–2012". Hydrology and Earth System Sciences. 18 (7): 2645–2656. Bibcode:2014HESS...18.2645P. doi: 10.5194/hess-18-2645-2014 . ISSN   1607-7938.
  42. ↑ Skála, Jan; Vácha, Radim; Čupr, Pavel (June 2018). "Which Compounds Contribute Most to Elevated Soil Pollution and the Corresponding Health Risks in Floodplains in the Headwater Areas of the Central European Watershed?". International Journal of Environmental Research and Public Health. 15 (6): 1146. doi: 10.3390/ijerph15061146 . ISSN   1660-4601.
  43. ↑ Rinklebe, Jörg; Franke, Christa; Neue, Heinz-Ulrich (October 2007). "Aggregation of floodplain soils based on classification principles to predict concentrations of nutrients and pollutants". Geoderma. 141 (3–4): 210–223. Bibcode:2007Geode.141..210R. doi:10.1016/j.geoderma.2007.06.001. ISSN   0016-7061.

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