Floodplain+connectivity

Flood Plain Form, Function, and Connectivity in River Restoration Kirsty Bramlett University of New Mexico River Restoration Spring, 2012 =__Introduction__= Floodplains are the areas of land lateral to a river that are inundated with water during a time when flow has been increased such as a flooding event, during snowpack runoff, or fed through groundwater. The floodplain is separated from the main channel of flow of the river. Floodplains have many definitions and delineations, which creates a challenge in studying these biomes that are neither entirely aquatic nor terrestrial. Even the River Continuum Concept, a paradigm shifting paper by Vannote (1980), which described trends in processes from headwaters through a large river, did not incorporate the floodplain influence (Benke, 2001). In the past floodplains were limited in definition to the area that is covered by water up to a 100-year storm event. This included the area known as the floodway and the flood fringe which is farther from the main channel. This definition was aimed at defining land for development purposes, agriculture, and in engineering assessment.

Floodplains have also been called the aquatic/terrestrial transition zone (ATTZ), which is the area that alternates between aquatic and terrestrial environments (Junk, Bayley and Sparks, 1989). They are also sometimes described interchangeably with the riparian zone. However for this paper the term floodplain will be used to describe the area that is inundated with water while continuing to examine the more complete picture contained in the aquatic/terrestrial transition zone. The spatial mosaic of floodplain habitats changes over time due primarily to processes of flooding, channel avulsion, and cut-and-fill alluviation resulting in dynamic patterns and rates of surface-hyporheic and groundwater exchange including associated biogeochemical processes (Tockner, Lorang and Stanford, 2010). Floodplains are an important aspect to overall river ecosystem health.

The floodplain is broader in its activities and functions than just the area of land that may be covered in water during a possible 100-year flood event, and has been outlined more clearly in the paper by Junk, Bayley and Sparks (1989) as, areas that are periodically inundated by the lateral overflow of rivers or lakes, and/or by direct precipitation or groundwater. These areas provide many vital functions to the river by providing nutrients, improving water quality, and also serving as a habitat that is high in biodiversity. In their natural state, floodplains are amongst the most dynamic and heterogeneous ecosystems, showing complex patterns of variation over a wide range of temporal and spatial scales (Tockner, Lorang and Stanford, 2010).

The actual area of a floodplain in a given river may be possible to define, however it is a dynamic changing system that can be aquatic, terrestrial, or a combination. The environmental change from the aquatic to the terrestrial phase at a specific point in a floodplain may be as severe as the change from a lake to a desert (Junk, Bayley and Sparks, 1989). This change occurs temporally and spatially like most of the other attributes of a river. The inshore edge of the aquatic environment that traverses along the floodplain is the ‘moving littoral’ (Junk, Bayley and Sparks, 1989). The littoral zone is the area submerged in water that lies between the main river channel’s limnetic zone and the adjacent floodplain. In the following figure the floodplain is adjacent to the littoral zone where the terrestrial plants lie.



=__Objectives__= The objectives of this Stream and Watershed Restoration Wiki are to impart knowledge of this developing and complex area of study, and to form a venue where information can be gathered and exchanged between those that are interested in River Restoration. Rivers are complex freshwater ecosystems with many distinct features as well as interrelated components. These components change spatially and temporally, which is also true of the information available through this Wiki. Each area will be linked throughout this document and can be found within the Stream and Watershed Restoration Wiki for further development of the many distinguishing aspects of the Earth’s rivers.

The objectives of this section are to: 1) clearly define the form, function and ecological purpose of a river’s floodplain; 2) to examine the changes that have occurred historically that have created a disconnection of the floodplain from the main channel and the effects that have occurred; 3) and to outline restoration methods that can be implemented to restore the function and connectivity of the floodplain to the river.

Floodplains have many known beneficial uses and studies continue to quantify those benefits. Anthropogenic changes to rivers have severely altered and in many cases completely disconnected rivers from the adjacent historical floodplain. In the past century, flow regulation has reduced or eliminated hydrological and ecological interactions between many rivers and their floodplains (Valett et al, 2005). The impact of these changes and the loss of the floodplain function and benefit must be assessed and quantified to fully understand the system as a whole and to improve restoration projects in the future. The movement of water through ground and surface systems, floodplains, wetlands and watersheds is perhaps the greatest indicator of the interaction of natural processes in the environment (Floodplain Natural Resources and Functions, 2012). Restoration efforts to improve the quality of the floodplain and its connection to the river should be a priority in many river restoration efforts. Analysis and discussion of these efforts will be defined.

=__Floodplain Functions__= There are many functions that a floodplain provides, and these produce benefits that are essential for ecosystem health. Floodplains of the world deserve increased attention for their inherent biodiversity, natural water cleansing and storage capacities, rejuvenation of productive soils, and role in maintaining fisheries, among other goods and services provided to human societies, and for their aesthetic and cultural appeal (Tockner, Lorang and Stanford, 2010). In arid and semiarid regions of the world, including the southwestern United States, Australia, and southwestern Africa, floods are major ecological organizers for lotic systems, floodplains, and riparian forests (Valett et al., 2005). The functions that floodplains provide are outlined here. However, this list is not exhaustive as the subject continues to be studied and developed.

__Floodwave Attenuation__
The first and most obvious is flood wave attenuation. A flood wave is the rise and fall of the water level in a river due to a storm or sudden snow melt. A functioning floodplain will receive the water as it rises and attenuates this wave by taking the energy from the wave laterally. Rivers without the function of flood wave attenuation will carry the energy from the wave further downstream, which impacts the aquatic life in the channel. The floodplain provides storage of water during a flood as well as conveyance. It reduces flow velocities and peaks. Floodplains store this water for use during dry periods. One acre of floodplain land flooded one foot deep ‍‍‍‍‍‍‍holds 330,000 gallons of water‍‍‍‍‍‍‍ (Floodplain Natural Resources and Functions, 2012).

__Habitat Diversity__
Floodplains also provide a rich ecosystem and are part of a total functioning system with the local environment, and provide habitat that is not available elsewhere. Flluvial processes of cut-and-fill alluviation create new channels, bars, and benches within a floodplain that in turn provides new surface for subsequent vegetative recruitment and growth resulting in a shifting mosaic of interconnected aquatic and terrestrial habitat patches (Tockner, Lorang and Stanford, 2010).The process of flooding laterally and subsequent return to terrestrial area provides an area that is necessary for speciation. Fluvial dependent species inhabit a variety of aquatic habitats, but require lotic conditions at some point during their life history stages (Barko, Herzog and O'Connell, 2006). Many of the organisms colonizing floodplains have developed adaptations that enable them to survive during an adverse period of drought or flood and even benefit from it (Junk, Bayley and Sparks, 1989).

This area is important for aquatic life such as fish. A functioning floodplain maintains biodiversity, provides breeding and feeding grounds for a variety of species, and enhances the integrity of the ecosystem. Floodplains have been reported to be used by fishes for feeding, spawning, rearing habitat, migration corridors, and refugia (Barko, Herzog and O'Connell, 2006). Fish yields and production are strongly related to the extent of accessible floodplain, whereas the main river is used as a migration route by most of the fishes (Junk, Bayley, and Sparks, 1989).

Semi-aquatic biota is specifically adapted to follow the transition zone between aquatic and terrestrial habitats as flow varies and many require both habitats to complete their life cycle (Tockner, Lorang and Stanford, 2010). Semi-aquatic biota includes plants whose roots are wholly or partly underwater, turtles, marine lizards, water snakes, marsh rabbits, beavers, muskrats, and otters. Regardless of regional characteristics, however, flood regimes play a vital role in defining aquatic habitats for fauna (Benke, 2001). These specific species and others need the aquatic and terrestrial aspects that a floodplain provides. The shifting habitat mosaic concept (SHM) recognizes that the interaction of physical and biotic processes in a floodplain produces a continually changing spatial pattern of habitats fostering high biodiversity (Tockner, Lorang and Stanford, 2010).

__Water Quality__
Floodplains are also an important factor in improving the water quality that enters a river after a storm. Nutrient cycling, contaminant filtration, water purification, bank stabilization, stream temperature maintenance, flow stabilization, flood attenuation, and habitat preservation are some of the numerous functions carried out by the floodplain and the riparian zone within that floodplain (Atkinson, Hunter and English, 2010). The floodplain filters impurities from runoff, processes and distributes organic wastes, and also moderates the temperature of the water. During a flooding event, especially in urban streams, water is carried directly from the watershed to the river including many of the contaminates found in urban areas including oil from automobiles and litter. The water that is transferred to a connected floodplain is processed by the riparian plantlife as well as treated during infiltration into the soil. Runoff will go directly into the riverstream without biological processing if it is not first contained within the floodplain.

__Nutrient Transfer__
The transfer of materials from the floodplain to the river as well as the river to the floodplain have been studied and has shown to have significant importance to the biodiversity in the river as well as the floodplain. This transfer of material is an essential component to the foodweb system. Floodplain vegetation helps define and stabilize habitats over an area greater than the river channel width, and its primary production in the form of litterfall ultimately fuels foodwebs in both the floodplain and river channel (Benke, 2001). Functioning and connected floodplains have an important transfer to and from the river. Materials are transported from the river to the floodplain (e.g. suspended sediments and nutrients) as well as from the floodplain to the river (e.g. organic detritus and algal biomass) (Tockner et al., 1999). This transfer is necessary for the development of sustainability of many biological processes. Floodplains are distinct because they do not depend on upstream processing inefficiencies of organic matter, although their nutrient pool is influenced by periodic lateral exchange of water and sediments with the main channel (Junk, Bayley, and Sparks, 1989). Floodplains change during the wet and dry cycle which impacts the transfer of nutrients. Both aspects are necessary for the environment. Wet-dry cycles affect all aspects of carbon and nutrient turnover, including mineralization, microbial growth, greenhouse gas losses and denitrification (Tockner, Lorang and Stanford, 2010). Many studies have been conducted and evidence shows that the nutrient transfer that occurs through connected floodplains is an important function. The floodplain is a complex mosaic of habitat patches, each slightly differing in productivity, standing biomass, soil organic content and capacity to transform organic matter (Tockner, Lorang and Stanford, 2010).

__Floodplain Connection__
A floodplain can only function as intended if it is connected to the river that it serves. The services provided by floodplains are inexorably linked to the frequency, seasonality and duration of surface flooding and of groundwater and channel water levels, and the management of these hydrological processes (Rouquette et al., 2011). Functioning floodplains go through a process of three phases. These phases are outlined in the paper “Hydrological connectivity, and the exchange of organic matter and nutrients in a dynamic river-floodplain system" (Tockner et al., 1999). Each of these phases has its own function and benefit to the environment and the river and cannot be separated from the floodplain system as a whole. Shifts in the strength and type of hydrological connectivity have major implications for structural and functional attributes of riverine floodplains (Tockner et al., 1999).

Phase I which occurs during the majority of the time is floodplain disconnection from the river. Some lakes and swamps are isolated from the main channel for many months or even years (Junk, Bayley and Sparks, 1989). Floodplains are not continuously receiving water during all storm events, and the first phase occurs most of the time. Nutrient levels and primary productivity are low in the floodplain (Tockner et al., 1999). The environment is stable during this phase and growth occurs. Autogenic processes dominating (e.g. sedimentation of autochthonous material, nutrient uptake and grazing) as the ‘biotic interaction phase’ (Tockner et al., 1999).

Phase II of floodplain connection is the seepage inflow phase. This occurs when water levels have risen in the river, however the floodplain has not been inundated. With only a subsurface connection upstream, the floodplain contributes already considerable amounts of algal biomass and DOC to the main river during phase II (Tockner et al., 1999). The main source of water during this phase is from groundwater. Water is able to cross into the floodplain laterally through the subsurface. Many of the storm events will result in a Phase II scenario. With increasing water levels, the floodplain shifts from a closed to a more open system fed by nutrient-rich ground water. Tockner et al. (1999) define phase II as the ‘primary production phase’.

Phase III of floodplain connection is the upstream surface connection this is also thought of as the ‘transport phase’. A flooding event occurs that overtops bankfull and inundates the floodplain with water. The timing of flooding and the period since the last flood are essential in explaining transport patterns (Tockner et al., 1999). Phase III is the mechanism for creating primary production. The floodplain shifts from an autotrophic system during phase II to a heterotrophic system during/after flooding (Tockner et al., 1999). Phase III occurs the least frequently of all the phases, however it is an important aspect of floodplain connection. For at least a portion of the year, however, the floodplain becomes an important part of the aquatic system food web as fishes migrate into these habitats and use the vast invertebrate food resource (Junk, Bayley and Sparks,1989).

=__Causes for Floodplain Disconnection__= Many changes have been made to rivers, especially in urban areas, that have affected the connection of floodplains and disrupted the natural phases that would normally occur in a functioning floodplain. The vast majority of human alteration to a free flowing river result in the control or dampening of flood flows, extraction of water, disruption of the sediment supply and stabilization of river banks. Each greatly reduces the dynamic physical drivers of floodplain dynamics, and thereby, directly impact biophysical processes that are essential for sustaining river ecosystem integrity (Tockner, Lorang and Stanford, 2010). Anthropogenic changes to the land uses along rivers, as well as the many methods employed to alter and manage the flows associated with these rivers, have created a disconnect between the river and its floodplain. Most large rivers in the temperate zone have been greatly impacted by the construction of hydropower plants, regulation work for navigation purposes, land reclamation projects and large-scale flood control measures (e.g. Dynesius & Nilsson, 1994). Floodplains have not only been altered by controlling the main channel, but by also altering the actual floodplain landscape. Flood-plains have been drained, deforested, and often converted to agriculture (Benke, 2001).

__Dams and Other Impoundments__
Dams for flood control, water storage, and hydropower have had a significant impact on floodplain biology. Dams and the reservoirs that are created as a result of dams artificially control the flow of the river, reduce flooding, and drastically alter sedimentation pathways. Dams and levees have caused the truncation of flood pulses to floodplains.Today, flood plains are among the most endangered ecosystems worldwide because most have been permanently inundated by reservoirs, which also limit or eliminate geomorphic forming flows, or are disconnected by dikes and armoured by bank stabilization structures (Tockner, Lorang and Stanford, 2010). Levees have been put into place along many reaches of rivers as a way of controlling flooding. This disconnects the river from the floodplain, and eradicates an entire system that had previously been in place. Along the Middle Rio Grande (New Mexico, USA), impoundments and levee construction have created riparian forests that differ in their inter-flood intervals (IFIs) because some floodplains are still regularly inundated by the flood pulse (i.e., connected), while other floodplains remain isolated from flooding (i.e., disconnected) (Valett et al., 2005).





__Channelization__ Rivers have been increasingly channelized as a way of controlling flooding. Channelization keeps the flow within the main river channel and reduces the amount of flow that can cross into the floodplain. One of the greatest influences that humans have had on the environment is the simplification of habitats, landscapes, and catchments (Tockner, Lorang and Stanford, 2010). Floodplains have been disconnected in an attempt to control flooding impacts.These channels are particularly dynamic, because an incised channel can contain larger peak flows and often cannot dissipate flow energy across the former floodplain. In the past century, flow regulation has reduced or eliminated hydrological and ecological interactions between many rivers and their floodplains (Valett et al., 2005).

The following youtube.com video is an appropriate example of channelization and how it affects the connectivity of the floodplain. []

__Water Withdrawals__
Water diversions from rivers for agricultural and human uses changes the amount of water available in a river and that change is carried downstream. It has been estimated that up to 90% of floodplains in Europe and North America have been “cultivated” and hydrologically modified for agriculture (Tockner and Stanford, 2002). The water that is withdrawn from the river from these diversions and withdrawals can significantly decrease the amount of flow in the river as compared to historical flow. The San Juan-Chama project in New Mexico is an example of a water diversion that adds flow to a reach of a river that would not normally be there while detracting from another system. Water diversions from a river by diverting flow from one area to another or withdrawing the water for consumption has an impact on the river system and decreases the connectivity to the floodplain by making floodplain inundation less likely. A notable example of water withdrawals can be seen on the Colorado River. The Colorado River rarely flows into the Gulf of California, let alone have a significant connection to the flooplain that runs adjacent to the 1,440 miles of river length.



=__Effects from Loss of Connectivity__= The loss of connectivity of a functioning floodplain has many impacts including loss of biodiversity, increase of invasive species, and degredation of the surrounding environment. Increasing river floodplain connectivity may be an effective approach for reducing the impacts of non-native fishes and maintaining biodiversity (Barko, Herzog and O'Connell, 2006). The changes that occur for each must be fully measured and analyzed to realize the full impact of the disconnection. Measuring and predicting consequences of changing landscapes, or in our case, riverscapes, is the fundamental problem in contemporary ecology (Tockner, Lorang and Stanford, 2010). Efforts must continue to study the effects from the loss of connectivity as well as to attempt to return the floodplain-river connection. Maintaining the connection between the river channel and floodplain is vital for diverse and productive invertebrate assemblages and the higher trophic levels that depend on them (Benke, 2001).

__Flood Pulse Concept__
A change in thought of river flooding and floodplain connections has occurred due to studies about the loss in the many functions previously outlined. In recent years, ecologists have recognized that the phenomenon of a flooding river often represents a beneficial ecological connection between the river and its semiaquatic floodplain, rather than an unpredictable catastrophic disturbance (Junk, Bayley and Sparks, 1989). The importance of Phase III and an event where the water over tops the main river channel banks has continued to be quantified. The principal driving force responsible for the existence, productivity, and interactions of the major biota in river-floodplain systems is the flood pulse (Junk, Bayley and Sparks, 1989). The flood pulse concept (FPC) emphasizes the pulsing of river discharge as the major driving force that determines the degree of connectivity, the exchange of matter and the processing of organic matter and nutrients across river-floodplain gradients (Tockner, Lorang and Stanford, 2010). This concept was first established by Junk and has since been researched and acknowleged by many experts in the field. The flood pulse concept of Junk, Bayley and Sparks (1989) and Bayley (1995) emphasizes th‍‍‍‍‍‍‍at inundation of the floodplain creates and maintains ‍‍‍‍‍‍‍riparian forests as some of the most productive and diverse ecosystems in the biosphere (Valett et al., 2005). The flood pulse event should not be limited to a specific climate, but is important in areas with frequent and infrequent flooding. In semiarid floodplains, water is scarce except during the flood pulse. Floodplain meadows are characteristic ecosystems which are heavily influenced by spring and winter flooding (Vecrin et al., 2002). The amount of flooding and the timing of the flooding event is also important to the floodplain-river connection.Timing, intensity, duration and frequency of flood pulses strongly influence what processes will be activated and at what rates they will proceed within the flood plain habitat complex (Tockner, Lorang and Stanford, 2010). Current efforts are underway to release waters from reservoirs in highly altered riverscapes to replicate a natural flooding event. These artificial floodpulses are used to return functions that had previously been lost. However, these flood events do not always have the same dimensions of what was experienced during historical flood events. Further investigation into the influence of floodpulse timing on both native and non-native assemblages in temperate rivers and understanding the life history of non-native fishes invading these rivers should be high research and management priorities (Barko, Herzog and O'Connell, 2006).



=__Restoration__= Restoration of floodplains and reconnection to the river system are important aspects to river restoration. The function of floodplains cannot be ignored. A focus of river restoration is to restore a more natural hydrograph with gradual changes in floodplain inundation and exchange processes (Tockner et al., 1999). The study of floodpulses, historical flows, and lateral connections in a way that can be accomplished is a necessary component of river restoration. We need system models that quickly respond in well-documented ways to natural and cultural forcings so that consequences of landscape change can be more effectively translated to management and policy (Tockner, Lorang and Stanford, 2010). Restoration efforts can most effectively occur from analysis of data available while continuing to assess what options are feasible and implementable. Possible solutions include removal of flood control impoundments such as dams and levees, controlled flood pulse events, and change of current floodplain practices to include floodplain ecosystem services.

A study on floodplain connectivity and its relation to fish development was conducted in 1993 during a flooding event. Data collection was performed during the 1993 flood in the unimpounded reach of the upper Mississippi River. This 500 year flood event provided a unique opportunity to investigate fish-floodplain function because the main river channel is otherwise typically disjunct from approximately 82% of its floodplain by an extensive levee system (Barko, Herzog and O'Connell, 2006). This study reemphasized the importance of restoring floodplain-river connections by quantifying an increase in native fish populations while also noting a decrease in invasive fish growth in areas with higher floodplain connection. The findings from the study provide much needed insight into fish-floodplain function in a temperate, channelized river system and suggest that lateral connectivity of the main river channel to less degraded reaches of its floodplain should become a management priority not only to maintain faunal biodiversity but also potentially reduce the impacts of non-native species in large river systems (Barko, Herzog and O'Connell, 2006).

__Case Study:Ecosystem Services__
The following case study involves the conversion of an altered floodplain in France to include various ecosystem services and how these changes were important to the immediate ecosystem as a whole. The study examined the restoration efforts to return a portion of an abandoned floodplain of the Meuse to produce high quality hay that is native to the area, under a low-intensity management regime (Vecrin et al., 2002). The area had previously been altered and used for agriculture of high-intensity crops. Priorities for the management of lowland rural floodplains in many parts of Europe have changed from a focus on agricultural production towards multi-functional landscapes that provide a range of environmental, social and economic benefits to society (Rouquette et al., 2011). This restoration effort converted the land that had been altered from its original state to arable land that had been highly fertilized, nutrient depleted, and inundated with invasive species. A conversion of arable fields might result in even stronger constraints for restoration due to a possible destruction of the meadow soil seed bank and modification of the soil chemical composition (Vecrin et al., 2002). Vecrin et al. (2002) explain a preferred technique for reversion of arable land to semi-natural grasslands in France. A commonly used technique is the sowing of meadow species, which is moderately expensive and considered most feasible by many practitioners. This technique leads, at the same time, to (1) a fast development of vegetation cover (Hutching & Booth, 1996), (2) a reduction in soil erosion and (3) a depletion of fertilizer residuals in the soil (Mitchley et al., 1996). The final report stated that the vegetation development in the restored meadow over three years showed that the mean species richness was significantly lower in the sown meadow than in the target communities and the floristic compositions were different. However, the similarity between restored and target meadows increased significantly with time, which suggests that the restoration of the sown meadow will proceed in the direction of the target meadow.

Another floodplain restoration effort considering ecosystem services was conducted in two rural floodplain in England. Rouquette et al. examined how varied landuses in a floodplain can be determined by the featured land cover and hydrological management of specific areas. The ecosystem services framework explored alternative management scenarios with objectives that included production, biodiversity, floodwater storage, agri-environment and income. Each environmental service featured a key challenge for the management of floodplains, and for sustainable natural resource management in general, is to examine the ecosystem services provided by alternative land-use types and to explore ways in which different management priorities can be integrated more effectively (Rouquette et al., 2011). The aim of this study was to find ways to sustainably work with the environment as opposed to completely altering the system.

__Case Study: Environmental Flows__
Managing flows within a river reach that has been physically altered to more closely match historical hydrograph flows is a new method being addressed in river restoration. Several recent reviews have emphasized the importance of reestablishing natural flow regimes, rather than just minimum flows, in regulated systems (Rouquette, 2011). These environmental flows take aspects of the flood pulse method and apply it to water releases from dams and reservoirs. This gives the floodplain an opportunity for connection to the river by Phase III during the flood pulse event. Hydrology plays a key role in determining the land use and habitat types that occur on lowland floodplains. Vegetation responds to the depth of the water table, the quality of the drainage and to the depth, duration and seasonality of flooding (Rouquette, 2011). The modeling techniques of environmental flows takes past flow records into account and creates a flow regime that will better match a natural system. Hydrological regimes are defined in terms of mean water-table depth, days with surface water and fluvial flood probability, and are based on expert knowledge and published sources (Rouquette, 2011). The nature of environmental flows aids in the health of the river along its length, but it also improves the river-floodplain connection that had previously been lost and addresses the needs of that ecosystem. An innovative approach to assess floodplain habitats is to calculate their ‘water age’, or the length of time that a parcel of water is contained in a particular habitat (Tockner, Lorang and Stanford, 2010).

=__Conclusion__= Floodplains have a specific design and use as it pertains to the environment and provide functions that cannot be provided elsewhere. Not only are natural floodplains among the most biologically complex and diverse landscapes on Earth, but they also contribute more than 25% of all terrestrial ecosystem services although they cover only 1.4% of the land surface area (Tockner, Lorang and Stanford, 2010). They are part of an integrated system that needs to be recognized and valued. Surface water, ground water, floodplains, wetlands and other features do not function as separate and isolated components of the watershed, but rather as a single, integrated natural system (Floodplain Natural Resources and Functions, 2012). The benefits and necessity of floodplains are evident in all types of environments whether it be desert or rainforest. Removal or alteration of a single process has ramifications throughout the system as a whole, and floodplains have continued to be lost through various disconnections. They are now among the most threatened landscapes worldwide with 47% of all animals federally endangered in the U.S. being freshwater species that occupy floodplains (Tockner, Lorang and Stanford, 2010). The loss of these systems must be addressed and actions taken to restore or preserve the remaining areas with functioning floodplains. This can be accomplished by studying the benefits, addressing the losses, and putting a value to the functions that they provide. Clearly, the relative contributions of habitats and natural inundation regime must be assessed in any river-floodplain ecosystem to understand its natural functioning (Benke, 2001). Studies have continued to show the importance of restoring floodplains to the adjacent river and providing lateral water inundation through a natural flood pulse regime.Years ago Poff and Ward (1989) and later Barinaga (1996) and Stanford et al. (1996) argued that restoration of riverine heterogeneity could only occur by naturalizing flows and sediment loading, removing lateral levees and other constraints, allowing the river to do the work of restoration (Tockner, Lorang and Stanford, 2010). Floodplain connection and interaction must continue to be prioritized in river restoration.



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