Journal articles on the topic 'Floodplain wetlands'
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1
Nyarko, Benjamin Kofi. "Wetland River Flow Interaction in a Sedimentary Formation of the White Volta Basin of Ghana." Earth Science Research 9, no. 1 (January 4, 2020): 15. http://dx.doi.org/10.5539/esr.v9n1p15.
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Groundwater resources in the floodplain wetlands of the White Volta River basin of Ghana is a major source of water for irrigation activities of communities living around and baseflow to sustain the flow of the river. Hydrology of the floodplain wetlands in the basin is complex, characterized by temporally variable storage volumes with erratic contribution to streamflow. For the continual usage of groundwater resources in the floodplains there is a need to study the form of interaction between the main river and floodplain wetlands. The study, adopted the PM-WIN (MODFLOW) model for simulating the interaction between the wetland and stream. Additionally, the lower boundary discharge output from the HYDRUS-1D model is the estimated recharge. This input quantifies the temporal and spatial variations in sub-surfaces discharges in the floodplain wetland. The simulation of the sub-surface hydraulic head of the wetland indicates a systematic variation relative to the White Volta River response to changes in the rainfall pattern. The interaction conditions vary from season to season with March, April, and May showing the least leakage (estimated values of 0.03 mm/day, 0.06 mm/day, and 0.15 mm/day, respectively) from the river into the floodplain wetland. Notably, the interaction between the wetland and the river as simulated is bidirectional. With most of the flow coming out from the river into the floodplain wetland, this condition persists in the months of August and September.
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Fu, Yunmei, Yanhui Dong, Yueqing Xie, Zhifang Xu, and Liheng Wang. "Impacts of Regional Groundwater Flow and River Fluctuation on Floodplain Wetlands in the Middle Reach of the Yellow River." Water 12, no. 7 (July 6, 2020): 1922. http://dx.doi.org/10.3390/w12071922.
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Floodplain wetlands are of great importance in the entire river and floodplain ecosystems. Understanding the hydrological processes of floodplain wetlands is fundamental to study the changes in wetlands caused by climate change and human activities. In this study, floodplain wetlands along the middle reach of the Yellow River were selected as a study area. The hydrological processes and the interactions between the river and the underlying aquifer were investigated by combining remote sensing, hydraulic monitoring, and numerical modeling. Wetland areas from 2014 to 2019 were extracted from Landsat 8 remote sensing images, and their correlation with the river runoff was analyzed. The results indicate that the river flow had a limited impact on the wetland size and so did groundwater levels, due to the strong reliance of wetland vegetation on water levels. Based on hydrological and hydrogeological conditions, a surface water–groundwater coupled numerical model was established. The comparison and correlation analysis between the monitored groundwater head and the simulated river stage also show that river flow did not play a first-order role in controlling the groundwater levels of wetlands in the study area. The simulation results also suggest that it is the regional groundwater flow that mainly sustains shallow groundwater of floodplain wetlands in the study area. The floodplain wetland of the study area was dynamic zones between the regional groundwater and river, the contrasting pattern of hydrological regimes on both banks of the Yellow River was due to a combination of regional groundwater flow and topography.
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Frazier, Paul, and Ken Page. "The effect of river regulation on floodplain wetland inundation, Murrumbidgee River, Australia." Marine and Freshwater Research 57, no. 2 (2006): 133. http://dx.doi.org/10.1071/mf05089.
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River regulation by headwater dams has altered the flow regime of rivers worldwide. For floodplain rivers, reduced connectivity between the main channel and floodplain wetlands has led to a decline in ecological health. Current river restoration theory advocates a return towards a more natural regime of floodplain wetland inundation. However, for many rivers, a poor understanding of the natural floodplain wetland inundation regime has hampered effective restoration management. This paper describes a technique for quantifying the effect of flow regulation on the inundation regime of floodplain wetlands on an extended reach of the Murrumbidgee River, Australia. A series of Landsat Thematic Mapper (TM) images, captured before and after a set of floods, was analysed to describe the relationship between flow and inundation for a 640 km river reach. These data were combined with historical regulated and modelled natural daily flow data to show that river regulation has reduced the duration and frequency of wetland inundation by ~40%. For the majority of wetlands the capture of small and medium floods in the headwater dams reduced wetland inundation substantially. However, for low connecting wetlands in reaches upstream of the main irrigation off-takes, summer irrigation flows have increased inundation.
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Ralph, Timothy J., Paul P. Hesse, and Tsuyoshi Kobayashi. "Wandering wetlands: spatial patterns of historical channel and floodplain change in the Ramsar-listed Macquarie Marshes, Australia." Marine and Freshwater Research 67, no. 6 (2016): 782. http://dx.doi.org/10.1071/mf14251.
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In the context of static conservation reserves, dynamic fluvial processes and patterns of river channel and floodplain change are problematic for environmental management. Floodplain wetlands that evolve by erosion and sedimentation experience changes in the location and extent of channels and wetlands regardless of conservation reserve boundaries. We describe historical channel and floodplain change in an Australian wetland of international ecological significance, the southern Macquarie Marshes, and synthesise the role of avulsion in wetlands that move laterally on the broader floodplain. Avulsion has shifted the foci of flooding and areas of aquatic habitat in the system over the last century. By ~1925, active wetlands surrounding the Old Macquarie River and the original conservation area contracted around Monkeygar Creek within the present nature reserve, and the boundary of this reserve has changed little since the 1940s. Ecological changes associated with continued wetland desiccation in the reserve triggered a recent Ramsar Article 3.2 notification for the Macquarie Marshes, prompting management responses from government agencies. Fluvial morphodynamics and their impacts on wetland ecology should be specifically recognised and integrated with adaptive management plans to combine new findings with lessons learned from previous intervention strategies for the long-term ecological sustainability of floodplain wetlands.
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Chomba, Innocent C., Kawawa E. Banda, Hessel C. Winsemius, Machaya J. Chomba, Mulema Mataa, Victoria Ngwenya, Henry M. Sichingabula, Imasiku A. Nyambe, and Bruce Ellender. "A Review of Coupled Hydrologic-Hydraulic Models for Floodplain Assessments in Africa: Opportunities and Challenges for Floodplain Wetland Management." Hydrology 8, no. 1 (March 11, 2021): 44. http://dx.doi.org/10.3390/hydrology8010044.
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Floodplain wetlands are a fundamental part of the African continent’s ecosystem and serve as habitat for fish and wildlife species, biodiversity, and micro-organisms that support life. It is generally recognised that wetlands are and remain fragile ecosystems that should be subject to sustainable conservation and management through the use of sustainable tools. In this paper, we propose a synthesis of the state of art concerning coupled hydrologic and hydraulic models for floodplains assessments in Africa. Case studies reviewed in this paper have pointed out the potential of applying coupled hydrologic and hydraulic models and the opportunities present to be used in Africa especially for data scarce and large basin for floodplain assessments through the use of available open access models, coupling frameworks and remotely sensed datasets. To our knowledge this is the first case study review of this kind on this topic. A Hydrological model coupled with Hydraulic Model of the floodplain provides improvements in floodplain model simulations and hence better information for floodplain management. Consequently, this would lead to improved decision-making and planning of adaption and mitigation measures for sound floodplain wetland management plans and programmes especially with the advent of climate change and variability.
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Jensen, Anne, Clare Nicolson, and Jason Carter. "Preservation and Management of Natural Wetlands in the South Australian Murray Valley." Water Science and Technology 29, no. 4 (February 1, 1994): 325–33. http://dx.doi.org/10.2166/wst.1994.0217.
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The impact of river regulation has been to reduce flood frequencies on the Murray floodplain below Mildura. The lower frequency of inundation of wetlands reduces the number of successful breeding and regeneration events in floodplain biota, causing a decline in the health and vigour of many floodplain plants and animals. The potential for rehabilitation of floodplain wetlands through increased flushing flows has been demonstrated. The ultimate aim is to enhance habitat value and achieve maximum biodiversity. Future opportunities are identified for hydrological manipulation within river operating strategies to extend beneficial management on a floodplain scale to improve wetland habitat. These can be combined with rehabilitation techniques such as specific water allocations, grazing controls and physical works on individual wetlands to ensure preservation and sustainable management of natural wetlands along the South Australian Murray Valley. Results so far indicate that successful restoration of the wetlands will take a number of flushing events and will be dependent primarily on the acceleration and protection of natural regeneration processes.
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Nafikova, Elvira, Dmitry Alexandrov, Anastasia Platonova, Kamila Gayanova, and Kamilla Chuvashaeva. "Depletion of the floodplain-channel complex of the river (Belaya river, Republic of Bashkortostan)." E3S Web of Conferences 244 (2021): 01012. http://dx.doi.org/10.1051/e3sconf/202124401012.
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The article presents a comprehensive assessment of the geoecological risk of the Belaya River floodplain (Republic of Bashkortostan, Russia). The risk assessment of the floodplain-channel complex includes the risk of depletion by the plant species composition and the risk of depletion of the ecological and hydrological states. Geographic information maps of the floodplain were compiled for vegetation and floodplain forests and wetlands. The extent of forest cover was chosen as an indicator of the floodplain’s resilience to the risk of depletion and decline. The calculation of the risk of depletion of floodplains based on the ecological and hydrological state was carried out taking into account the changes in floodplain areas over the past 10 years, data on the catchment of ground and surface waters, “sealed” areas and the annual average discharge. The assessment and zoning of the river floodplain territory was carried out according to the proposed method.
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Li, Heying, Jiayao Wang, Jianchen Zhang, Fen Qin, Jiyuan Hu, and Zheng Zhou. "Analysis of Characteristics and Driving Factors of Wetland Landscape Pattern Change in Henan Province from 1980 to 2015." Land 10, no. 6 (May 27, 2021): 564. http://dx.doi.org/10.3390/land10060564.
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The study of the temporal and spatial evolution of wetland landscapes and its driving factors is an important reference for wetland ecological restoration and protection. This article utilized seven periods of land use data in Henan Province from 1980 to 2015 to extract the spatial distribution characteristics of wetlands and analyze the temporal and spatial changes of wetlands in Henan Province. Transfer matrix, landscape metrics, correlation analysis, and redundancy analysis were applied to calculate and analyze the transformation types and area of wetland resources between all consecutive periods, and then the main driving factors of wetland expansion/contraction were explored. First, the total wetland area in Henan Province increased by 28% from 1980 to 2015, and the increased wetland area was mainly constructed wetlands, including paddy field, reservoir and pond, and canal. Natural wetlands such as marsh, lake, and floodplain decreased by 74%. Marsh area declined the most during 1990–1995, and was mainly transformed into floodplain and “Others” because of agricultural reclamation, low precipitation, and low Yellow River runoff. The floodplain area dropped the most from 2005 to 2010, mainly converted to canals and “Others” because of reclamation, exploitation of groundwater, the construction of the South–to–North Water Transfer Project, and recreational land development. Second, the results of correlation analysis and redundancy analysis indicated that economic factors were positively correlated with the area of some constructed wetlands and negatively correlated with the area of some natural wetlands. Socioeconomic development was the main driving factors for changes in wetland types. The proportion of wetland habitat in Henan Province in 2015 was only 0.3%, which is low compared to the Chinese average of 2.7%. The government should pay more attention to the restoration of natural wetlands in Henan Province.
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Singh, Manudeo, and Rajiv Sinha. "Integrating Hydrological Connectivity in a Process–Response Framework for Restoration and Monitoring Prioritisation of Floodplain Wetlands in the Ramganga Basin, India." Water 14, no. 21 (November 3, 2022): 3520. http://dx.doi.org/10.3390/w14213520.
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Floodplain wetlands are critical for sustaining various ecological and hydrological functions in a riverine environment. Severe anthropogenic alterations and human occupation of floodplains have threatened these wetlands in several parts of the world. A major handicap in designing sustainable restoration and monitoring strategies for these wetlands is the lack of scientific process-based understanding and information on the basin-scale controls of their degradation. Here, we offer a novel approach to integrate the connectivity of the wetlands with the surrounding landscape along with other attributes such as stream density, hydrometeorological parameters, and groundwater dynamics to explain their degradation and then to prioritise them for restoration and monitoring. We hypothesise that the best possible connectivity scenario for the existence of a wetland would be if (a) the wetland has a high connectivity with its upslope area, and (b) the wetland has a low connectivity with its downslope region. The first condition ensures the flow of water into the wetland and the second condition allows longer water residence time in the wetland. Accordingly, we define four connectivity-based wetland health scenarios—good, no impact, bad, and worst. We have implemented the proposed method in 3226 wetlands in the Ramganga Basin in north India. Further, we have applied specific selection criteria, such as distance from the nearest stream and stream density, to prioritise the wetlands for restoration and monitoring. We conclude that the connectivity analysis offers a quick process-based assessment of wetlands’ health status and serves as an important criterion to prioritise the wetlands for developing appropriate management strategies.
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Zhang, Yihao, Jianzhong Yan, Xian Cheng, and Xinjun He. "Wetland Changes and Their Relation to Climate Change in the Pumqu Basin, Tibetan Plateau." International Journal of Environmental Research and Public Health 18, no. 5 (March 7, 2021): 2682. http://dx.doi.org/10.3390/ijerph18052682.
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Wetland ecosystems play one of the most crucial roles in the world. Wetlands have the functions of ecological water storage, water supply, and climate regulation, which plays an indispensable role in global environmental security. The Pumqu River Basin (PRB) is located in an area with extremely vulnerable ecological environment, where climate change is obvious. Understanding wetland distribution, changes and causes in the PRB are of great importance to the rational management and protection of wetlands. Using the Landsat series satellite images, wetlands of this area in 2000, 2010, and 2018 were extracted. The results showed that (1) there were obvious regional differences in wetland types and their distribution patterns in the basin. Wetlands were mainly distributed in areas with slopes less than 12° and at elevations between 4000 m and 5500 m. (2) During the past 20 years, the wetland area in the basin decreased, and the changing trend of wetlands was different. Palustrine wetlands decreased tremendously, riverine and lacustrine wetlands first decreased and then increased, while floodplain wetlands first increased and then decreased. Palustrine wetlands were reclaimed to cultivated land, but the proportion of reclamation is small. (3) Climate dominated wetland changes in the PRB. The changes in riverine and lacustrine wetlands were mainly affected by the warm-season average temperature, the change in palustrine wetlands was mainly related to the annual precipitation and the warm-season average temperature, and the change in floodplain wetlands was related to the warm-season precipitation. To achieve sustainable development, the government plays a guiding role and actively formulates and implements wetland protection policies, such as restricting or prohibiting grazing on wetlands, which play an important role in wetland protection and restoration.
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Adame, M. F., H. Franklin, N. J. Waltham, S. Rodriguez, E. Kavehei, M. P. Turschwell, S. R. Balcombe, P. Kaniewska, M. A. Burford, and M. Ronan. "Nitrogen removal by tropical floodplain wetlands through denitrification." Marine and Freshwater Research 70, no. 11 (2019): 1513. http://dx.doi.org/10.1071/mf18490.
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Excess nitrogen (N) leading to the eutrophication of water and impacts on ecosystems is a serious environmental challenge. Wetlands can remove significant amounts of N from the water, primarily through the process of denitrification. Most of our knowledge on wetland denitrification is from temperate climates; studies in natural tropical wetlands are very scarce. We measured denitrification rates during a dry and a wet season in five floodplain forests dominated by Melaleuca spp., a coastal freshwater wetland of tropical Australia. We hypothesised that the denitrification potential of these wetlands would be high throughout the year and would be limited by N and carbon (C) availability. Mean potential denitrification rates (Dt) were 5.0±1.7mgm2h–1, and were within the reported ranges for other tropical and temperate wetlands. The rates of Dt were similar between the dry and the wet seasons. From the total unamended denitrification rates (Dw, 3.1±1.7mgm2h–1), 64% was derived from NO3– of the water column and the rest from coupled nitrification–denitrification. The factor most closely associated with denitrification was background water NO3–-N concentrations. Improved management and protection of wetlands could play an important role in improving water quality in tropical catchments.
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Angarita, Héctor, Albertus J. Wickel, Jack Sieber, John Chavarro, Javier A. Maldonado-Ocampo, Guido A. Herrera-R., Juliana Delgado, and David Purkey. "Basin-scale impacts of hydropower development on the Mompós Depression wetlands, Colombia." Hydrology and Earth System Sciences 22, no. 5 (May 8, 2018): 2839–65. http://dx.doi.org/10.5194/hess-22-2839-2018.
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Abstract. A number of large hydropower dams are currently under development or in an advanced stage of planning in the Magdalena River basin, Colombia, spelling uncertainty for the Mompós Depression wetlands, one of the largest wetland systems in South America at 3400 km2. Annual large-scale inundation of floodplains and their associated wetlands regulates water, nutrient, and sediment cycles, which in turn sustain a wealth of ecological processes and ecosystem services, including critical food supplies. In this study, we implemented an integrated approach focused on key attributes of ecologically functional floodplains: (1) hydrologic connectivity between the river and the floodplain, and between upstream and downstream sections; (2) hydrologic variability patterns and their links to local and regional processes; and (3) the spatial scale required to sustain floodplain-associated processes and benefits, like migratory fish biodiversity. The implemented framework provides an explicit quantification of the nonlinear or direct response relationship of those considerations with hydropower development. The proposed framework was used to develop a comparative analysis of the potential effects of the hydropower expansion necessary to meet projected 2050 electricity requirements. As part of this study, we developed an enhancement of the Water Evaluation and Planning system (WEAP) that allows resolution of the floodplains water balance at a medium scale (∼ 1000 to 10 000 km2) and evaluation of the potential impacts of upstream water management practices. In the case of the Mompós Depression wetlands, our results indicate that the potential additional impacts of new hydropower infrastructure with respect to baseline conditions can range up to one order of magnitude between scenarios that are comparable in terms of energy capacity. Fragmentation of connectivity corridors between lowland floodplains and upstream spawning habitats and reduction of sediment loads show the greatest impacts, with potential reductions of up to 97.6 and 80 %, respectively, from pre-dam conditions. In some development scenarios, the amount of water regulated and withheld by upstream infrastructure is of similar magnitude to existing fluxes involved in the episodic inundation of the floodplain during dry years and, thus, can also induce substantial changes in floodplain seasonal dynamics of average-to-dry years in some areas of the Mompós Depression.
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Dlamini, Mandla, George Chirima, Mbulisi Sibanda, Elhadi Adam, and Timothy Dube. "Characterizing Leaf Nutrients of Wetland Plants and Agricultural Crops with Nonparametric Approach Using Sentinel-2 Imagery Data." Remote Sensing 13, no. 21 (October 22, 2021): 4249. http://dx.doi.org/10.3390/rs13214249.
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In arid environments of the world, particularly in sub-Saharan Africa and Asia, floodplain wetlands are a valuable agricultural resource. However, the water reticulation role by wetlands and crop production can negatively impact wetland plants. Knowledge on the foliar biochemical elements of wetland plants enhances understanding of the impacts of agricultural practices in wetlands. This study thus used Sentinel-2 multispectral data to predict seasonal variations in the concentrations of nine foliar biochemical elements in plant leaves of key floodplain wetland vegetation types and crops in the uMfolozi floodplain system (UFS). Nutrient concentrations in different floodplain plant species were estimated using Sentinel-2 multispectral data derived vegetation indices in concert with the random forest regression. The results showed a mean R2 of 0.87 and 0.86 for the dry winter and wet summer seasons, respectively. However, copper, sulphur, and magnesium were poorly correlated (R2 ≤ 0.5) with vegetation indices during the summer season. The average % relative root mean square errors (RMSE’s) for seasonal nutrient estimation accuracies for crops and wetland vegetation were 15.2 % and 26.8%, respectively. There was a significant difference in nutrient concentrations between the two plant types, (R2 = 0.94 (crops), R2 = 0.84 (vegetation). The red-edge position 1 (REP1) and the normalised difference vegetation index (NDVI) were the best nutrient predictors. These results demonstrate the usefulness of Sentinel-2 imagery and random forests regression in predicting seasonal, nutrient concentrations as well as the accumulation of chemicals in wetland vegetation and crops.
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Thomas, David H. L. "Artisanal Fishing and Environmental Change in a Nigerian Floodplain Wetland." Environmental Conservation 22, no. 2 (1995): 117–26. http://dx.doi.org/10.1017/s037689290001016x.
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Floodplain wetlands are of major importance in semi-arid Africa, providing agricultural, livestock, forestry, and fisheries, products as well as many other goods and services. Through a case-study of a floodplain wetland in northern Nigeria, it is demonstrated that the factors determining the characteristics of floodplain fishermen, defined in terms of how they fish, where they fish, and when they fish, are spatially and temporally very complex and may best be analysed within a simple systems framework.Despite the important values and functions that floodplains provide, many have been degraded owing to the construction of dams within their catchments. Studies of the social and economic impact of these developments tend to have adopted an ‘ecosystem’ approach to analysis that conceals the socio-economic complexity of the floodplain. However, if proposals to manage the water resources of river basins effectively are to be successfully implemented, it will be essential to understand the complexity of socioeconomic relations of floodplain users and their interaction with the environment. In conclusion, there is a need for much more detailed socio-economic studies that explore the ways in which floodplain inhabitants use the system in space and time.
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Lenders, H. J. R., J. A. M. Garritsen, and R. S. E. W. Leuven. "Environmental Quality and Legal Protection of Floodplain Wetlands in the Dutch Part of the Rhine Basin." Water Science and Technology 29, no. 3 (February 1, 1994): 293–95. http://dx.doi.org/10.2166/wst.1994.0123.
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Large parts of the floodplains in the Dutch Rhine basin can be considered wetlands of international importance. Few data are available concerning the threats to these wetlands. Legal protection and the principle of ' wise use' of the wetlands, as stipulated in the Ramsar Convention, are hardly being implementated in national and local policies. Until 1993 none of the floodplains in the river basin has actually been designated as wetland of international importance. In zoning plans the ' wetland function' is hardly ever recognized as the main function. A relatively small part of the river floodplains is designated as nature reserves or protected areas. More research should be carried out concerning the environmental quality of and ecological standards for wetlands. The physical threats of deterioration, disturbance and fragmentation of habitats deserve special attention. Legal protection and 'wise use' of wetlands in the Rhine basin should be further implemented.
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Braccia, A., and D. P. Batzer. "Breakdown and invertebrate colonization of dead wood in wetland, upland, and river habitats." Canadian Journal of Forest Research 38, no. 10 (October 2008): 2697–704. http://dx.doi.org/10.1139/x08-113.
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Breakdown of woody debris in river and upland habitats as well as the interactions between wood and invertebrates have been well described. Studies of wood in wetlands are rare, and far less is known about breakdown and invertebrate use of wood in these transitional habitats. This study experimentally assessed breakdown and invertebrate colonization of wood in a floodplain wetland and directly related patterns in the wetland to adjacent river and upland habitats. Over a 2.7 year period, we monitored breakdown and invertebrate presence in 10 cm diameter × 150 cm long sweetgum ( Liquidambar styraciflua L.) logs in a floodplain wetland (n = 8), river (n = 5), and upland (n = 4) habitat. Mass loss, decay condition change, and C/N ratios of wetland wood more closely resembled upland than river wood. The overall invertebrate assemblage associated with wetland wood was also more similar to that associated with upland than river wood. Breakdown and invertebrate colonization of wood in the floodplain wetland shared more characteristics with upland than river wood, perhaps because of the seasonal nature of flooding in the wetland. However, the ecology of wood in wetlands also had unique characteristics compared with either the uplands or the river.
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Kobayashi, Tsuyoshi, Timothy J. Ralph, Pranay Sharma, and Simon M. Mitrovic. "Influence of historical inundation frequency on soil microbes (Cyanobacteria, Proteobacteria, Actinobacteria) in semi-arid floodplain wetlands." Marine and Freshwater Research 71, no. 5 (2020): 617. http://dx.doi.org/10.1071/mf18468.
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Cyanobacteria and other microbes are important moderators of biogeochemical processes in semi-arid floodplain wetlands with varying inundation regimes. Inundation is a key environmental driver for floodplain biological communities. Little is known about the effect of historical inundation frequency on the spatial abundance of floodplain–wetland Cyanobacteria and other microbes. In this study, soil samples were collected at two locations with a gradient of low-to-high inundation frequency in the Macquarie Marshes, south-east Australia. We used high-throughput sequencing to estimate the proportional abundance of the soil Cyanobacteria and other dominant microbes, targeting the bacterial 16S rRNA gene. Of the microbes recovered, Cyanobacteria constituted proportionally a minor component, relative to other dominant phyla like Proteobacteria and Actinobacteria. Linear regression (generalised least-squares) models accounting for spatial autocorrelation showed that historical inundation frequency had no significant effect on the proportional abundance of Cyanobacteria at both wetlands studied. However, inundation frequency had a significant positive effect on the proportional abundance of Proteobacteria and a significant negative effect on the proportional abundance of Actinobacteria. Cyanobacteria seem to occupy a different hydrological niche from Proteobacteria and Actinobacteria in semi-arid floodplain wetlands, suggesting taxon-dependent response of floodplain microbial communities to varying inundation regimes and associated soil conditions in those environments.
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Magolan, Jessica Lynn, and Joanne Nancie Halls. "A Multi-Decadal Investigation of Tidal Creek Wetland Changes, Water Level Rise, and Ghost Forests." Remote Sensing 12, no. 7 (April 3, 2020): 1141. http://dx.doi.org/10.3390/rs12071141.
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Coastal wetlands play a vital role in protecting coastlines, which makes the loss of forested and emergent wetlands devastating for vulnerable coastal communities. Tidal creeks are relatively small hydrologic areas that feed into larger estuaries, are on the front lines of the interface between saltwater and freshwater ecosystems, and are potentially the first areas to experience changes in sea level. The goal of this study was to investigate wetland changes through time at two tidal creeks (Smith Creek and Town Creek) of the Cape Fear River estuary in southeastern North Carolina, USA, to determine if there is a spatial relationship between habitat change, physical geography characteristics, and the rate of wetland migration upstream. Historic aerial photography and recent satellite imagery were used to map land cover and compute change through time and were compared with derived physical geography metrics (sinuosity, creek width, floodplain width, floodplain elevation, and creek slope). The primary results were: (1) there was a net gain in emergent wetlands even accounting for the area of wetlands that became water, (2) wetlands have migrated upstream at an increasing rate through time, (3) land cover change was significantly different between the two creeks (P = 0.01) where 14% (67.5 ha) of Smith Creek and 18% (272.3 ha) of Town Creek transitioned from forest to emergent wetland, and (4) the transition from emergent wetland to water was significantly related to average change in creek width, floodplain elevation, and average water level. In conclusion, this research correlated habitat change with rising water level and identified similarities and differences between neighboring tidal creeks. Future research could apply the methodologies developed here to other coastal locations to further explore the relationships between tides, sea level, land cover change, and physical geography characteristics.
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Wang, Lixin, Huamin Liu, Yuhong Liu, Jianwei Li, Hongbo Shao, Wei Wang, and Cunzhu Liang. "Soil Characteristic Comparison of Fenced and Grazed Riparian Floodplain Wetlands in the Typical Steppe Region of the Inner Mongolian Plateau, China." Scientific World Journal 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/765907.
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In recent decades, degradation of ecosystem in the steppe region of the Inner Mongolia Plateau, especially in riparian floodplain wetlands, has become a significant ecological crisis. Not uncommonly, with the increasing of livestock in the Inner Mongolian steppe region, a riparian floodplain wetland is becoming a hotspot area of grazing for local herdsmen. Hence, it is essential to understand degradation mechanisms of riparian floodplain wetland ecosystems caused by extensive grazing. In this study, the spatial distribution of soil compaction, salinity, total nitrogen, total phosphorus, organic carbon, and microbial biomass C and N were investigated. The results showed that grazing led to an increase in soil compaction and soil surface salinity, which significantly lowered levels of total N, P, and TOC in the soil surface. Grazing decreased soil microbial biomass C and N concentration in the lower riparian floodplain wetland, whereas it significantly increased soil microbial biomass C and N concentration in the higher riparian floodplain wetland. Elevation differences in the riparian floodplain wetland increased spatial heterogeneity in the soil and thus resulted in different influence of grazing on wetland soils and ecosystem. Therefore, elevation differences and grazing intensity were the main factors controlling soil characteristics in the riparian floodplain wetland of this region.
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VanZomeren, Christine M., Jacob F. Berkowitz, A. Maria Lemke, and Krista G. Kirkham. "Soil P Storage Capacity in Agricultural Treatment Wetlands: Can a System Designed for N Reduction Also Retain P?" Wetlands 40, no. 3 (October 16, 2019): 503–14. http://dx.doi.org/10.1007/s13157-019-01205-3.
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Abstract Increasing interest focuses on utilizing wetlands to reduce nutrient loading to surface waters. The current study examines soil P storage capacity in three treatment wetlands designed to decrease N loading from an agricultural tile drainage system in Illinois. Adjacent farm field and restored floodplain wetland soils were also evaluated. Results demonstrate that wetland soils sequestered P; however, the magnitude of P retention varied significantly across treatment systems and floodplain wetlands related to differences in soil properties. Soil P storage capacity increased in the direction of water flow, but varied across treatment wetlands; soils ranged from P sinks (5.8 ± 1.5 mg P kg−1) to potential P sources (−17.2 ± 2.0 mg P kg−1). Farm fields displayed the highest water soluble P levels (11.3 ± 1.5 mg P kg−1) and represented the largest potential source of P with a mean storage capacity of −48.6 ± 6.8 mg P kg−1. A phosphorus saturation ratio threshold value of 0.10 differentiated between potential P sources and sinks. Findings suggest wetlands receiving P loadings from tile drainage accumulate soil P over time, but maintaining P removal efficiency in treatment wetlands may require periodic management to decrease soil P concentrations via nutrient removal and/or soil amendments.
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Ringeval, B., S. Houweling, P. M. van Bodegom, R. Spahni, R. van Beek, F. Joos, and T. Röckmann. "Methane emissions from floodplains in the Amazon Basin: towards a process-based model for global applications." Biogeosciences Discussions 10, no. 10 (October 29, 2013): 16713–803. http://dx.doi.org/10.5194/bgd-10-16713-2013.
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Abstract. Tropical wetlands are estimated to represent about 50% of the natural wetland emissions and explain a large fraction of the observed CH4 variability on time scales ranging from glacial-interglacial cycles to the currently observed year-to-year variability. Despite their importance, however, tropical wetlands are poorly represented in global models aiming to predict global CH4 emissions. This study documents the first regional-scale, process-based model of CH4 emissions from tropical floodplains. The LPX-Bern Dynamic Global Vegetation Model (LPX hereafter) was modified to represent floodplain hydrology, vegetation and associated CH4 emissions. The extent of tropical floodplains was prescribed using output from the spatially-explicit hydrology model PCR-GLOBWB. We introduced new Plant Functional Types (PFTs) that explicitly represent floodplain vegetation. The PFT parameterizations were evaluated against available remote sensing datasets (GLC2000 land cover and MODIS Net Primary Productivity). Simulated CH4 flux densities were evaluated against field observations and regional flux inventories. Simulated CH4 emissions at Amazon Basin scale were compared to model simulations performed in the WETCHIMP intercomparison project. We found that LPX simulated CH4 flux densities are in reasonable agreement with observations at the field scale but with a~tendency to overestimate the flux observed at specific sites. In addition, the model did not reproduce between-site variations or between-year variations within a site. Unfortunately, site informations are too limited to attest or disprove some model features. At the Amazon Basin scale, our results underline the large uncertainty in the magnitude of wetland CH4 emissions. In particular, uncertainties in floodplain extent (i.e., difference between GLC2000 and PCR-GLOBWB output) modulate the simulated emissions by a factor of about 2. Our best estimates, using PCR-GLOBWB in combination with GLC2000, lead to simulated Amazon-integrated emissions of 44.4 ± 4.8 Tg yr−1. Additionally, the LPX emissions are highly sensitive to vegetation distribution. Two simulations with the same mean PFT cover, but different spatial distributions of grasslands within the basin modulated emissions by about 20%. Correcting the LPX simulated NPP using MODIS reduces the Amazon emissions by 11.3%. Finally, due to an intrinsic limitation of LPX to account for seasonality in floodplain extent, the model failed to reproduce the seasonality in CH4 emissions. The Inter Annual Variability (IAV) of the emissions increases by 90% if the IAV in floodplain extent is account for, but still remains lower than in most of WETCHIMP models. While our model includes more mechanisms specific to tropical floodplains, we were unable to reduce the uncertainty in the magnitude of wetland CH4 emissions of the Amazon Basin. Our results stress the need for more research to constrain floodplain CH4 emissions and their temporal variability.
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Krause, S., and A. Bronstert. "An advanced approach for catchment delineation and water balance modelling within wetlands and floodplains." Advances in Geosciences 5 (December 16, 2005): 1–5. http://dx.doi.org/10.5194/adgeo-5-1-2005.
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Abstract. Water balance of wetlands within lowland floodplains is strongly influenced by the temporally variable spatial extent of the interactions between groundwater and surface water. A robust algorithm will be introduced which makes it possible to delineate the interaction zone between the lowland river and the floodplain. This interaction zone is specified as the "Direct Catchment" which is defined by the part of the connected floodplain in which wetland water balance is mainly affected by the surface water dynamics of the adjacent river. The delineation algorithm is based on transfer functions which were assessed by local simulation results of the integrated water balance and nutrient dynamics model IWAN. The transfer functions are further determined by mean annual groundwater depths and by simulated groundwater dynamics. They are controlled by simulation results of the maximal transversal extent of surface water influence on groundwater stages. The regionalisation of the developed delineation algorithm leads to the specification of the maximal extent of groundwater - surface water - interaction processes along the river. By application of this approach to the Havel River basin, located within lowlands of Northeaster Germany, it was possible to specify a 998.1 km2 part of the floodplain which is directly connected with the surface waters and thus called the "Direct Catchment" of the Havel river. The IWAN model was applied to simulate the water balance of the floodplain. The simulation results prove the tight interaction between river and floodplain. It is shown that the spatially and temporally variable influences of the connected floodplain on the river discharge were only important during low discharge in summer.
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Poi, Alicia S. G., Juan J. Neiff, Sylvina L. Casco, and Luciana I. Gallardo. "Macroinvertebrates of Eichhornia crassipes (Pontederiaceae) roots in the alluvial floodplain of large tropical rivers (Argentina)." Revista de Biología Tropical 68, S2 (October 22, 2020): S104—S115. http://dx.doi.org/10.15517/rbt.v68is2.44342.
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Introduction: Eichhornia crassipes is a dominant aquatic plant of neotropical-river floodplains and is invasive in warm waters of different continents. Plants provide food and habitat for fish, especially Prochilodus lineatus and Gymnotus omarorum, which are relevant to subsistence fishing by local indigenous communities. Objective: In this study we describe the main traits of E. crassipes floating meadows, and analyze the abundance and composition of macroinvertebrate assemblages associated with their roots in two floodplain wetlands of the Paraná River (within the Ramsar site Wetlands Chaco) and of the Pilcomayo River (within the Pilcomayo River National Park). Methods: During spring and summer, the macroinvertebrates were collected in monospecific stands of E. crassipes with a net of 962 cm2 area and 500 µm mesh size. Leaf density, the biomass of leaves and roots, the length of leaves and roots, and the water quality were measured simultaneously. Results: Temperature, oxygen concentration, and nutrient content were significantly higher and electrical conductivity was lower in the Pilcomayo than in the Paraná floodplain. E. crassipes growing in the Pilcomayo floodplain had longer leaves and less root biomass than those found in the Paraná floodplain. The number of macroinvertebrates per 1 000 g root dry weight and per m2 was significantly different between both floodplains, but the taxon richness was similar. Non Metric Multidimensional Scaling analysis differentiated the abundance of 14 selected taxa between both floodplains, and showed a high correlation between the environmental variables and macroinvertebrate abundance. The most abundant taxonomic groups in the Paraná River floodplain were oligochaetes (Naididae), ostracods mainly Cytheridella ilosvayi and larvae of non-biting midges (Chironomidae). Two families, Hydrobiidae (Heleobia parchappii) and Chironomidae accounted for 49.3 % of the total abundance in the Pilcomayo floodplain. The prawns Macrobrachium jelskii and M. amazonicum, frequent in the Pilcomayo floodplain, were not found in the Paraná floodplain. Conclusions: The different environmental conditions in both floodplains affect the abundance, composition, and the dominance of macroinvertebrate assemblages; however, the total taxa richness was similar. The area occupied by E. crassipes in the floodplains of these rivers provides the habitat that contributes most to overall biotic diversity, which must be considered in management strategies.
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Ringeval, B., S. Houweling, P. M. van Bodegom, R. Spahni, R. van Beek, F. Joos, and T. Röckmann. "Methane emissions from floodplains in the Amazon Basin: challenges in developing a process-based model for global applications." Biogeosciences 11, no. 6 (March 21, 2014): 1519–58. http://dx.doi.org/10.5194/bg-11-1519-2014.
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Abstract. Tropical wetlands are estimated to represent about 50% of the natural wetland methane (CH4) emissions and explain a large fraction of the observed CH4 variability on timescales ranging from glacial–interglacial cycles to the currently observed year-to-year variability. Despite their importance, however, tropical wetlands are poorly represented in global models aiming to predict global CH4 emissions. This publication documents a first step in the development of a process-based model of CH4 emissions from tropical floodplains for global applications. For this purpose, the LPX-Bern Dynamic Global Vegetation Model (LPX hereafter) was slightly modified to represent floodplain hydrology, vegetation and associated CH4 emissions. The extent of tropical floodplains was prescribed using output from the spatially explicit hydrology model PCR-GLOBWB. We introduced new plant functional types (PFTs) that explicitly represent floodplain vegetation. The PFT parameterizations were evaluated against available remote-sensing data sets (GLC2000 land cover and MODIS Net Primary Productivity). Simulated CH4 flux densities were evaluated against field observations and regional flux inventories. Simulated CH4 emissions at Amazon Basin scale were compared to model simulations performed in the WETCHIMP intercomparison project. We found that LPX reproduces the average magnitude of observed net CH4 flux densities for the Amazon Basin. However, the model does not reproduce the variability between sites or between years within a site. Unfortunately, site information is too limited to attest or disprove some model features. At the Amazon Basin scale, our results underline the large uncertainty in the magnitude of wetland CH4 emissions. Sensitivity analyses gave insights into the main drivers of floodplain CH4 emission and their associated uncertainties. In particular, uncertainties in floodplain extent (i.e., difference between GLC2000 and PCR-GLOBWB output) modulate the simulated emissions by a factor of about 2. Our best estimates, using PCR-GLOBWB in combination with GLC2000, lead to simulated Amazon-integrated emissions of 44.4 ± 4.8 Tg yr−1. Additionally, the LPX emissions are highly sensitive to vegetation distribution. Two simulations with the same mean PFT cover, but different spatial distributions of grasslands within the basin, modulated emissions by about 20%. Correcting the LPX-simulated NPP using MODIS reduces the Amazon emissions by 11.3%. Finally, due to an intrinsic limitation of LPX to account for seasonality in floodplain extent, the model failed to reproduce the full dynamics in CH4 emissions but we proposed solutions to this issue. The interannual variability (IAV) of the emissions increases by 90% if the IAV in floodplain extent is accounted for, but still remains lower than in most of the WETCHIMP models. While our model includes more mechanisms specific to tropical floodplains, we were unable to reduce the uncertainty in the magnitude of wetland CH4 emissions of the Amazon Basin. Our results helped identify and prioritize directions towards more accurate estimates of tropical CH4 emissions, and they stress the need for more research to constrain floodplain CH4 emissions and their temporal variability, even before including other fundamental mechanisms such as floating macrophytes or lateral water fluxes.
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Kronvang, Brian, Carl C. Hoffmann, and Rianne Dröge. "Sediment deposition and net phosphorus retention in a hydraulically restored lowland river floodplain in Denmark: combining field and laboratory experiments." Marine and Freshwater Research 60, no. 7 (2009): 638. http://dx.doi.org/10.1071/mf08066.
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Restoration of river systems allowing the transformation of former drained and dry riparian areas into riparian wetlands will increase the overbank storage of sediment and sediment-associated phosphorus (P). Wetland restoration is therefore a cost-effective mitigation measure to reduce the sediment and nutrient transport to river systems. The studied floodplain of the River Odense was restored in 2003 by remeandering the river channel along a 6-km reach. The restoration project involved 78 ha of riparian areas that were transformed from mainly arable land to extensive grassland and wetlands. The aim of the study was to quantify and model sediment and particulate P deposition on restored river floodplains. The present study suggests that during a 47-day flooding period, the river floodplain is able to retain 9–14.8% of the sediment and 1.1–3.7% of the particulate P transported in the river. Incubation experiments further showed that a maximum of 11–25% of the deposited phosphorus can be released as dissolved inorganic phosphorus following deposition. The results from the best deposition model (R2 = 0.42 for sediment and R2 = 0.44 for particulate P) show that work should be done to further improve the performance of these models.
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Garnett, Jeffrey A., and Darold P. Batzer. "Longitudinal variation in community structure of floodplain fishes along two rivers of the southeastern USA." Canadian Journal of Fisheries and Aquatic Sciences 71, no. 9 (September 2014): 1291–302. http://dx.doi.org/10.1139/cjfas-2013-0422.
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Many studies have examined whether longitudinal variation exists in fish communities within stream channels. Yet despite the acknowledged importance of adjacent floodplain ecosystems, no study has investigated longitudinal variation in fish communities in floodplain wetlands. We conducted a study to determine if distinct fish communities exist between upper and lower river floodplains. We predicted that floodplains in the upper portions of a watershed will be dominated by opportunistic riverine fish. In contrast, floodplains farther downstream in the watershed will primarily consist of obligate floodplain fishes. We sampled fishes at 21 floodplain sites along the lengths of the Oconee–Altamaha and Broad–Savannah river systems of Georgia, USA, during the 2008 and 2009 flood seasons. A modified mark–recapture method was utilized to estimate probabilities of species detection and occupancy. Ordination and analysis of similarity using species site occupancy estimates identified two unique communities related to floodplain position, and indicator species analysis supported our hypothesis of community distinction based on life history traits. Water resource managers should consider how flood pulse character influences fish communities when regulating flow regimes.
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Higgisson, William, Linda Broadhurst, Foyez Shams, Bernd Gruber, and Fiona Dyer. "Reproductive Strategies and Population Genetic Structure in Two Dryland River Floodplain Plants, Marsilea drummondii and Eleocharis acuta." Genes 13, no. 9 (August 23, 2022): 1506. http://dx.doi.org/10.3390/genes13091506.
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Aquatic plants share a range of convergent reproductive strategies, such as the ability to reproduce both sexually and asexually through vegetative growth. In dryland river systems, floodplain inundation is infrequent and irregular, and wetlands consist of discrete and unstable habitat patches. In these systems, life history strategies such as long-distance dispersal, seed longevity, self-fertilisation, and reproduction from vegetative propagules are important strategies that allow plants to persist. Using two aquatic plants, Marsilea drummondii and Eleocharis acuta, we investigated the proportions of sexual and asexual reproduction and self-fertilisation by employing next-generation sequencing approaches, and we used this information to understand the population genetic structure of a large inland floodplain in western New South Wales (NSW), Australia. Asexual vegetative reproduction and self-fertilisation were more common in M. drummondii, but both species used sexual reproduction as the main mode of reproduction. This resulted in a highly differentiated genetic structure between wetlands and a similar genetic structure within wetlands. The similarity in genetic structure was influenced by the wetland in the two species, highlighting the influence of the floodplain landscape and hydrology on structuring population genetic structure. The high levels of genetic variation among wetlands and the low variation within wetlands suggests that dispersal and pollination occur within close proximity and that gene flow is restricted. This suggests a reliance on locally sourced (persistent) seed, rather than asexual (clonal) reproduction or recolonisation via dispersal, for the population maintenance of plants in dryland rivers. This highlights the importance of floodplain inundation to promote seed germination, establishment, and reproduction in dryland regions.
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Watkins, Susanne C., G. P. Quinn, and Ben Gawne. "Changes in organic-matter dynamics and physicochemistry, associated with riparian vegetation loss and river regulation in floodplain wetlands of the Murray River, Australia." Marine and Freshwater Research 61, no. 10 (2010): 1207. http://dx.doi.org/10.1071/mf09312.
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Extensive clearing of floodplain forests potentially reduces organic matter available to floodplain wetlands. Furthermore, on rivers regulated to provide irrigation water in summer, floodplain wetlands that were previously inundated in spring, now flood in summer/autumn. In the Murray–Darling Basin, Australia, this has changed the timing of organic matter entering the aquatic phase, since leaf fall peaks in summer. Field surveys and mesocosm experiments on floodplain wetlands on the River Murray revealed faster processing rates of leaves in summer/autumn than spring, and no difference between cleared and forested wetlands. Temperature and leaf carbon : nitrogen ratio could not explain these differences, and instead, changes to leaf chemistry associated with ‘terrestrial ageing’ between peak leaf fall in summer and inundation in spring is more likely. The results indicated that the reduction of input of organic matter through riparian tree clearing and changing the timing of inundation interact to alter organic-matter standing stocks and rates of decomposition in floodplain wetlands. Restoring both natural timing of high flows and riparian vegetation might be required for recovery of these wetlands.
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Li, Yunliang, Jing Yao, Guizhang Zhao, and Qi Zhang. "Evidences of hydraulic relationships between groundwater and lake water across the large floodplain wetland of Poyang Lake, China." Water Supply 18, no. 2 (July 17, 2017): 698–712. http://dx.doi.org/10.2166/ws.2017.150.
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Abstract Hydraulic relationship between wetlands and lakes has become an important topic for the scientific and decision-making communities. Poyang Lake, an open freshwater lake in China, and the extensive floodplain wetland surrounding the lake, plays an important role in protecting the biodiversity of this internationally recognized wetland system. This paper is the first field-based study into an investigation of the groundwater dynamics in the floodplain wetland and the associated hydraulic relationship with the lake using hydrological, hydrochemical and stable isotope evidence, as exemplified by Poyang Lake wetland. Results show that groundwater stores within the floodplain wetland exhibit spatial and temporal variability in terms of the magnitudes of groundwater level variations. Floodplain groundwater fluctuations largely reflect patterns of the precipitation and the lake water level; however, the groundwater dynamics are highly affected by the variations in the lake water level, rather than local precipitation. Floodplain wetland is most likely to receive the lake water during spring and summer and may recharge the lake during periods of low lake water level. Additionally, floodplain groundwater displays similar hydrochemical and environmental isotope signatures to that of the lake at different sampling periods, indicating a close hydraulic relationship between groundwater and the lake throughout the year.
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Leigh, Catherine, Fran Sheldon, Richard T. Kingsford, and Angela H. Arthington. "Sequential floods drive 'booms' and wetland persistence in dryland rivers: a synthesis." Marine and Freshwater Research 61, no. 8 (2010): 896. http://dx.doi.org/10.1071/mf10106.
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Flow is a key driver regulating processes and diversity in river systems across a range of temporal and spatial scales. In dryland rivers, variability in the timing and scale of floods has specific ecological significance, playing a major role in sustaining biotic diversity across the river-floodplain mosaic. However, longitudinal effects of floods are equally important, delivering water downstream through channels and wetland complexes. Interaction among spatially distributed wetlands, their connecting channel and floodplain geomorphology and the temporally variable flow events not only creates the spatial complexity in dryland rivers but also determines temporal persistence of wetlands. These act as hydrological ‘sponges’, absorbing water from upstream and needing to fill before releasing water downstream. Sequential high flow events are essential for the ecological persistence of riverine wetlands and the transmission of flows further downstream through the channel network. These flood sequences maintain aquatic refugia and drive booms in productivity sustaining aquatic and terrestrial biota over large spatial and temporal scales. Disrupting the sequence, with modified flow regimes and water removal for diversion (e.g. irrigation), significantly reduces the opportunity for wetland replenishment. As a result, the benefits of sequential flooding to the wetland ‘sponges’ and their biotic communities will be lost.
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Cameron, Robert. "Red Maple, Acer rubrum, Wetland Composition and Structure in Nova Scotia." Canadian Field-Naturalist 123, no. 3 (July 1, 2009): 221. http://dx.doi.org/10.22621/cfn.v123i3.968.
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Red Maple (Acer rubrum) wetlands occur when Red Maple dominated forest occupies imperfectly drained to saturated soils. Plots were established in 28 Red Maple wetlands in Nova Scotia to document structure and plant composition. Non-metric multidimensional scaling (NMDS) was used to assess vegetation differences by wetland type (floodplain, depression, slope) and geographic region (inland vs. coastal and western vs. eastern shore). Seventy-eight species of vascular plants and 35 species of non-vascular plants were found in plots. Two species of rare vascular plants and four rare Sphagnum species were found in plots or within the wetlands. Sphagnum species richness was very high. Red Maple wetlands are structurally complex, often having five distinct vertical layers. NMDS species composition analyses suggest little difference between wetland types and geographic regions. Given the diversity of vascular and non-vascular plants and the structural complexity of Red Maple wetlands in Nova Scotia, these wetlands make a significant contribution to the biodiversity and heterogeneity of the landscape.
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Ocock, J. F., K. J. Brandis, B. J. Wolfenden, K. M. Jenkins, and S. Wassens. "Gut content and stable isotope analysis of tadpoles in floodplain wetlands." Australian Journal of Zoology 66, no. 4 (2018): 261. http://dx.doi.org/10.1071/zo18043.
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Larval amphibians (tadpoles) are an important link in aquatic food webs, as they can be highly abundant consumers and prey for a wide variety of predators. Most tadpoles are considered omnivores, predominately grazing on algae, detritus and macrophytes, though recent work has identified greater plasticity and breadth in diet than previously considered. We used gut content and stable isotope analysis (SIA) in a baseline study to determine the important dietary items (ingested material) and food sources (assimilated material) for tadpoles of two abundant generalist frog species in regulated floodplain wetlands of the Murrumbidgee River, south-east Australia. We identified a wide variety of dietary items in the gut contents, including whole microcrustaceans, filamentous algae and macrophytes. The composition of several ingested food items was correlated with their availability in each wetland. However, SIA identified biofilm as the food source most consistently assimilated across several wetlands, though microcrustaceans and algae contributed when abundant. Biofilm is likely the most important basal food item for tadpoles in floodplain wetlands because it is ubiquitous and has a high nutritional quality. Identifying important food sources is a crucial step towards developing management strategies for promoting tadpole recruitment in regulated wetlands.
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Galatowitsch, M. L., and D. P. Batzer. "Benefits and costs ofLeptophlebia(Ephemeroptera) mayfly movements between river channels and floodplain wetlands." Canadian Journal of Zoology 89, no. 8 (August 2011): 714–23. http://dx.doi.org/10.1139/z11-044.
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Dramatic drift of nymphs of the mayflies Leptophlebia Westwood, 1840 and Siphlonurus Eaton, 1868 (47 600 individuals/trap per hour) was observed between a southeastern USA river and adjacent floodplain following natural flooding events. Active movements of these nymphs against the water flow were also detected. Large numbers of leptophlebid nymphs reside in floodplains during the winter and spring, but how and why they colonize and develop in temporary habitats is uncertain. We detected few environmental advantages (i.e., temperature, food abundance or quality) for mayflies in floodplains compared with river habitats. Despite this, experiments indicated that mayflies had 36% higher growth rates in the floodplain than in the river and demonstrated tolerance to short-term drying (up to 12 d). Migration entails costs of migrating against flows during daylight when vulnerability to predation is high, colonizing a habitat subject to drying, hypoxia, and supporting amphibian predators, with few apparent benefits. Dispersal into wetlands may be attributed to avoiding swift river flows or exploiting largely fishless habitats. However, dispersal could be an evolutionary relic of behavior beneficial in more northerly habitats; our study populations of Leptophlebia mayflies were at the southern extreme of their range and perhaps operating suboptimally. Our results emphasize the importance of river–floodplain linkages to the ecology of both habitats.
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Gordon, Brad A., Olivia Dorothy, and Christian F. Lenhart. "Nutrient Retention in Ecologically Functional Floodplains: A Review." Water 12, no. 10 (October 4, 2020): 2762. http://dx.doi.org/10.3390/w12102762.
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Nutrient loads in fresh and coastal waters continue to lead to harmful algal blooms across the globe. Historically, floodplains—low-lying areas adjacent to streams and rivers that become inundated during high-flow events—would have been nutrient deposition and/or removal sites within riparian corridors, but many floodplains have been developed and/or disconnected. This review synthesizes literature and data available from field studies quantifying nitrogen (N) and phosphorus (P) removal within floodplains across North America and Europe to determine how effective floodplain restoration is at removing nutrients. The mean removal of nitrate-N (NO3−-N), the primary form of N in floodplain studies, was 200 (SD = 198) kg-N ha−1 year−1, and of total or particulate P was 21.0 (SD = 31.4) kg-P ha−1 year−1. Based on the literature, more effective designs of restored floodplains should include optimal hydraulic load, permanent wetlands, geomorphic diversity, and dense vegetation. Floodplain restorations along waterways with higher nutrient concentrations could lead to a more effective investment for nutrient removal. Overall, restoring and reconnecting floodplains throughout watersheds is a viable and effective means of removing nutrients while also restoring the many other benefits that floodplains provide.
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Karim, Fazlul, Steve Marvanek, Linda E. Merrin, Daryl Nielsen, Justin Hughes, Danial Stratford, and Carmel Pollino. "Modelling Flood-Induced Wetland Connectivity and Impacts of Climate Change and Dam." Water 12, no. 5 (April 30, 2020): 1278. http://dx.doi.org/10.3390/w12051278.
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Hydrological connectivity between rivers and wetlands is considered one of the key critical factors for the integrity of floodplain landscapes. This study is a comprehensive modelling exercise on quantifying flood-induced wetland connectivity and the potential impacts of climate and water storage in an unregulated river basin in northern Australia. Flood inundation was simulated using a two-dimensional hydrodynamic model and the connectivities between wetlands and rivers were calculated using geoprocessing tools in ArcGIS. Wetlands in the floodplain were identified using waterbody maps derived from satellite imagery. A broadly representative sample of 20 wetlands were selected from 158 wetlands in the Mitchell basin considering location, size and spatial distribution. Five flood events ranging from 1 in 2 to 1 in 100 years were investigated to evaluate how connectivity changes with flood magnitude. Connectivities were assessed for the current condition as well as for two scenarios of future climate (Cwet and Cdry) and one scenario of dam storage. Results showed that a 1 in 100 years event inundated about 5450 km2 of land compared to 1160 km2 for a 1 in 2 years event. Average connectivity of wetlands in the Mitchell basin varies from 1 to 5 days for the floods of 1 in 2 to 1 in 26 years. As expected, a large flood produces longer duration of connectivity relative to a small flood. Results also showed that reduction in mean connectivity under a dryer climate (up to 1.8 days) is higher than the possibility of increase under a wet climate (up to 1 day). The impacts of a water storage, in the headwater catchment, are highly pronounced in terms of inundation and wetland connectivity (e.g., mean connectivity reduced by 1.7 days). The relative change in connectivity is higher for a small flood compared to that of a large event. These results demonstrate that there is a possibility of both increase and decease in connectivity under future climate. However, any water storage will negatively impact the connectivity between floodplain waterbodies and thus reduce the material exchange resulting in a reduction in primary and secondary productions in rivers and wetlands.
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Y.S. Mah, Darrien, Rosmina A. Bustami, and Frederik J. Putuhena. "Incorporating Floodplain Inundation as a Strategy in Flood Mitigation Plan." Journal of Civil Engineering, Science and Technology 3 (December 1, 2012): 41–45. http://dx.doi.org/10.33736/jcest.101.2012.
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This paper is promoting the awareness that nature and engineering structure can co-exist together. Natural floodplain inundation is usually restrained to separate floodplain lands for human uses. In contrary to conventional flood control systems, a vision of restoring floodplain inundation in Kuching Bypass Floodway is presented as a flood mitigation plan. Modelling of the approach indicates a reduction of flooded areas up to 61%. By means of modelling, portions of floodplains are virtually preserved in their natural states and functions, a role that often has been undervalued. Floodplain permits storage and conveyance of floodwaters. At the same time, it provides replenishment of the adjoining wetlands. The strategy proves beneficial to both human and natural systems. It also calls for a systemic change in flood management that we can live with the natural forces instead of forbidding them.
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Gao, Zhao Qin, Jun Hong Bai, Di Chen, Qing Qing Zhao, and Jun Jing Wang. "Effects of Different Flooding Frequencies on Soil Nitrogen Mineralization in Typical Floodplain Wetlands under Aerobic Conditions." Advanced Materials Research 1010-1012 (August 2014): 381–84. http://dx.doi.org/10.4028/www.scientific.net/amr.1010-1012.381.
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Soil profiles from 0 to 80 cm depth were collected at five typical zones (including permanently flooded floodplain (B), 1-year floodplain (O), 5-year floodplain (F), 10-year floodplain (T), and 100-year floodplain (H)) which are divided by different flooding frequencies along the direction penperdicular to the river channel in different floodplain wetlands of Xianghai National Nature Reserve of China. A 14-day incubation experiment was carried out at 25°C in the dark to reveal the effects of different flooding frequencies on nitrogen mineralization rates. Our results showed that nitrogen mineralization rates showed an alternative tend of “increasing and decreasing”in the soil profiles at five sampling zones except the 1-year floodplain and permanent floodplain. The nitrogen mineralization rates were lower in permanently flooded floodplain soils compared to another four floodplain wetlands with different flooding frequencies. Additionally, nitrogen mineralization rates were significantly correlated with electrical conductivity, total soluble salt, pH values and salinity.
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Puthiyottil, M., U. K. Sarkar, L. Lianthuamluaia, G. Karnatak, M. A. Hassan, S. Kumari, B. D. Ghosh, and B. K. Das. "Floodplain wetlands of eastern India in a changing climate: Trophic characterization, ecological status, and implications for fisheries." Aquatic Ecosystem Health & Management 24, no. 3 (July 1, 2021): 47–56. http://dx.doi.org/10.14321/aehm.024.03.07.
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Abstract India is endowed with vast floodplain wetland resources (0.5 million ha), which provide both livelihood and nutritional security to much of the rural populace. These biologically sensitive ecosystems are threatened by a range of anthropogenic and climatic factors. Assessment of their ecological vulnerability, and of the environmental threats that they face, is essential both in evaluating the health of these ecosystems and in developing sustainable management strategies for conservation and fisheries enhancement. In this context, eight wetlands in the Ganga basin were studied for two consecutive years across the seasons and were characterized ecologically based on chlorophyll a, primary productivity, and trophic state index. A warming temperature (+0.20 – +0.47 °C) and a decreasing total annual rainfall (257–580 mm) have been observed along the Ganga basin in the last three decades. The chlorophyll a (mean ± S.E.) content of the water varied from 4.08 ± 1.04 to 38.0 ± 14.11 µg l-1. The high primary productivity, gross primary productivity/plankton respiration ratio and trophic state index correlated positively with the high fish yield in the wetlands. Analysis of data based on Carlson's method revealed five wetlands in the eutrophic category, whereas based on Lamparelli's method, two wetlands fall into the eutrophic category. The Lamparelli TSI value ranged from 54.1 in Majharia to 65.8 in Kararia among the wetlands. The Bishnupur wetland in West Bengal and Kararia wetland in Bihar were found to be eutrophic due to cascading sewage incursion from nearby towns. These altered ecosystems with high TSI values were prudently exploited by selecting suitable fish species for high fish production, and a fish yield of 1200 kg ha-1 yr-1 was achieved in Bishnupur. The study revealed that eutrophic wetlands can be strategically managed for maintaining both ecosystem services and fish production. Careful selection of suitable fish species and stocking rate is crucial. The planned disposal and treatment of sewage is recommended to maintain the ecological health of floodplain wetlands for sustainable fisheries management in the context of a changing climate.
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Gondwe, M. J., C. Helfter, M. Murray-Hudson, P. E. Levy, E. Mosimanyana, A. Makati, K. B. Mfundisi, and U. M. Skiba. "Methane flux measurements along a floodplain soil moisture gradient in the Okavango Delta, Botswana." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 379, no. 2210 (September 27, 2021): 20200448. http://dx.doi.org/10.1098/rsta.2020.0448.
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Data-poor tropical wetlands constitute an important source of atmospheric CH 4 in the world. We studied CH 4 fluxes using closed chambers along a soil moisture gradient in a tropical seasonal swamp in the Okavango Delta, Botswana, the sixth largest tropical wetland in the world. The objective of the study was to assess net CH 4 fluxes and controlling environmental factors in the Delta's seasonal floodplains. Net CH 4 emissions from seasonal floodplains in the wetland were estimated at 0.072 ± 0.016 Tg a −1 . Microbial CH 4 oxidation of approximately 2.817 × 10 −3 ± 0.307 × 10 −3 Tg a −1 in adjacent dry soils of the occasional floodplains accounted for the sink of 4% of the total soil CH 4 emissions from seasonal floodplains. The observed microbial CH 4 sink in the Delta's dry soils is, therefore, comparable to the global average sink of 4–6%. Soil water content (SWC) and soil organic matter were the main environmental factors controlling CH 4 fluxes in both the seasonal and occasional floodplains. The optimum SWC for soil CH 4 emissions and oxidation in the Delta were estimated at 50% and 15%, respectively. Electrical conductivity and pH were poorly correlated ( r 2 ≤ 0.11, p < 0.05) with CH 4 fluxes in the seasonal floodplain at Nxaraga. This article is part of a discussion meeting issue 'Rising methane: is warming feeding warming? (part1)'.
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Jensen, Alexandria K., and William I. Ford. "Quantifying Nitrate Dynamics of a Confluence Floodplain Wetland in a Disturbed Appalachian Watershed: High-Resolution Sensing and Modeling." Transactions of the ASABE 62, no. 6 (2019): 1545–65. http://dx.doi.org/10.13031/trans.13278.
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Abstract. Floodplain wetlands often form at confluences of main river channels and small, low-order tributary streams, yet their impact on nutrient removal and downstream loading is poorly understood. We coupled high-resolution water quality data with deterministic numerical modeling of hydrologic, hydraulic, and biochemical processes impacting nitrate fate and transport in a confluence floodplain wetland along the Ohio River from June 2017 to May 2018. The modeling results were used to quantify loading from a disturbed forested watershed (Fourpole Creek watershed) and the nitrate removal capacity of the wetland. Loading from the Fourpole Creek watershed to the wetland was on the same order of magnitude of other disturbed forested systems on an annual basis (3.6 kg N ha-1 year-1); however, the timing of peak nitrate loading and concentration from the tributary was associated with high flow conditions, contrasting with the timing of loadings typical of disturbed forested landscapes. Our results show that coupling the model with high-resolution data allowed us to estimate removal rates in the wetland, suggesting that 2.6% to 58.5% (optimally 12.7%) of nitrate was removed on an annual basis, despite the wetland comprising only 0.42% of the overall drainage area. We found that increasing inundation of the wetland confluence promoted enhanced residence times of stormflows and was the most important driver of nitrate removal rate and loading, with peak wetland inundation periods representing 26% of the removal load but occurring only 9% of the time. The findings of this study highlight the importance of using high-resolution data-model integration to quantify nutrient dynamics in complex landscapes, identifies the significance of connectivity of watershed nitrate loadings to floodplain wetland soils, and highlights the importance that these features will have in the future, given the enhanced potential for harmful algal blooms in the Ohio River. Keywords: Confluence floodplain wetlands, High-resolution water quality data, Nitrate fate and transport modeling, Nitrate loading, Wetland nitrate removal.
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Messer, Tiffany, Kyle Douglas-Mankin, Natalie Nelson, and James Randall Etheridge. "Wetland Ecosystem Resilience: Protecting and Restoring Valuable Ecosystems." Transactions of the ASABE 62, no. 6 (2019): 1541–43. http://dx.doi.org/10.13031/trans.13578.
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HighlightsWe provide context and perspectives on articles in the Wetland Ecosystem Resilience collection.Insights gained on wetland resilience to sea-level rise and climate change, land use and drainage, and nutrients. Abstract. The objective of this article is to introduce a collection of articles that explore current research and scientific thought on wetland ecosystem resilience. The collection contains articles on wetland resilience to climate change, agricultural land use-driven change, and recreational land use, along with evaluations of wetland resilience through high-resolution monitoring and modeling tools. Wetland settings in the U.S. span tidal marshes and coastal plain non-riverine wetlands in North Carolina, prairie potholes in Iowa, Appalachian floodplain wetlands, and floating treatment wetlands in the Midwest. The studies in this collection found vertical accretion rates of 0.7 to 4.0 mm year-1 in a tidal marsh, a wide range of potential wetland hydroperiod responses to climate change, substantial decreases in inundation period, crop yield, and surface-water nitrate (but increases in phosphorus) in artificially drained potholes, and nitrate removal in carbon-amended floating treatment wetlands. Further work is needed to better understand how to design and enhance wetland systems in agricultural regions, better preserve wetland ecosystem services in areas affected by land use and climate change, and provide technical standards for the wide range of designs currently used for wetland treatment systems. Keywords: Agricultural wetlands, Resiliency, Temporal data, Treatment wetlands, Water chemistry, Water quality, Water treatment
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Grenfell, S., and M. Grenfell. "Characterising the late Quaternary facies stratigraphy of floodplains in South Africa." South African Journal of Geology 124, no. 4 (December 1, 2021): 963–76. http://dx.doi.org/10.25131/sajg.124.0056.
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Abstract South African river floodplains and their alluvial deposits reflect a diversity of geological and geographical drivers. We use a genetic geomorphic classification system originally developed for dryland wetlands to characterise geomorphic processes and potential successions of sedimentary fill for South African floodplains. Using case studies from the literature, we consider differences between alluvial rivers and mixed bedrock-alluvial rivers in the context of macro-scale geomorphic setting, and evaluate the impact of the setting on floodplain persistence and potential as a palaeo-environmental archive. Sedimentary facies associations represented in South African floodplains, including lateral and oblique accretion, channel, channel infill, levee vertical accretion, floodplain vertical accretion and debris flow deposits, are also evaluated. Floodplains of South Africa’s interior are typically mixed bedrock-alluvial as channel beds are set upon or close to bedrock and sediment thickness is limited. By contrast some floodplains in tectonic basin settings have sediment deposits exceeding 30 m in thickness. The resulting rivers are alluvial, and thus able to adjust their width, depth and slope to accommodate changes in discharge and sediment supply. Similarly, coastal floodplain rivers are alluvial due to downcutting during the last glacial maximum and subsequent sedimentary infilling as sea levels rose. When considering the potential of floodplains as palaeoarchives of environmental change, two considerations emerge. First, floodplain stratigraphy is not a response to a single variable due to complex process-form feedbacks. Rather, floodplain stratigraphy is an outcome of both autogenic and allogenic processes. Second, most South African floodplains are zones of sediment recycling, and as such, preservation potential is typically low. Thus, although floodplain settings of the interior may be a few million years old, the sediment within them may be only thousands to tens of thousands of years old. Our review indicates that research has historically focused on meandering river and mixed bedrock-alluvial anabranching river floodplains, while understanding of other floodplain sub-types remains limited.
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Chipps, Steven R., Daniel E. Hubbard, Kent B. Werlin, Neil J. Haugerud, Kipp A. Powell, Jo Thompson, and Tom Johnson. "Association between wetland disturbance and biological attributes in floodplain wetlands." Wetlands 26, no. 2 (June 2006): 497–508. http://dx.doi.org/10.1672/0277-5212(2006)26[497:abwdab]2.0.co;2.
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Desta, Mare Addis, Gete Zeleke, William A. Payne, and Wubneh Belete Abebe. "Impact of Rice Expansion on Traditional Wetland Management in the Tropical Highlands of Ethiopia." Agriculture 12, no. 7 (July 19, 2022): 1055. http://dx.doi.org/10.3390/agriculture12071055.
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Despite the fact that rice was only recently brought to Ethiopia, the Ethiopian government has dubbed it the “millennium crop” because of its importance as a food security crop, as well as a source of revenue and job possibilities. Rice production is being practiced on wetland areas and floodplains; however, no attention has been given to the sustainability of these wetlands, or to the integration of different previous indigenous activities, such as livestock rearing and farming of different crops in the area. This study aims to investigate the impact of rice expansion on traditional wetland management in the Fogera floodplain wetlands of the Lake Tana basin. Data were generated via interviews and the application of GIS and remote sensing. The survey questionnaire was administered to 385 rice-producing farmers. The respondents (87%) confirmed that increases in the price of rice encouraged them to shift from the cultivation of conventional crops to rice farming. Subsequently, between the years 1973 and 2014, wetland areas have been reduced from 3114 ha to 1060 ha, accompanied by a high rate of expansion in rice production in the area. Major activities being pursued in the wetlands of the study area do not consider environmental impacts. As a result, the diverse ecosystem services available in the past have been compromised through time. Sense of ownership of wetland resources and their benefit shall be communicated to reduce abusive utilization. Therefore, the policies, strategies, and development activities implementation need to consider environmental issues in rice production enhancement endeavors.
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Wang, Xinjian, Jinyun Chen, and Lizhi Zhou. "Effects of Human Activities on the Diversity of Waterbirds Wintering in a Shallow Lake of the Middle and Lower Yangtze River Floodplain, China." Diversity 12, no. 8 (August 3, 2020): 302. http://dx.doi.org/10.3390/d12080302.
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Human activity is the major factor driving the wetland degradation in shallow lakes. Human exploitation of lake wetlands alters the habitats of wintering waterbirds, and, in turn, waterbird diversity in the shallow lakes. In the present study, we surveyed species composition, abundance, and habitat characteristics of waterbirds in three types of wetland habitats (natural lakeside wetlands, paddy fields, and aquaculture ponds) at Caizi Lake, a shallow lake in the middle and lower Yangtze River during the wintering period, and investigated the effects of habitat change driven by human activity on the diversity of wintering waterbirds. There were significant differences in species composition and abundance among the three wetland habitats (natural lakeside wetlands, aquaculture ponds, and artificial paddy fields); however, there were no significant differences among the habitats with respect to the number of waterbirds. The numbers of overwintering waterbird species and waterbird individuals in aquaculture ponds and lakeside wetlands were significantly higher than the numbers in the paddy fields, indicating that wintering waterbirds prefer natural lake wetlands and aquaculture ponds. Principal component analysis of the three wetland habitat types revealed that factors influencing waterbird diversity include wetland area, vegetation cover, water level, and degree of human interference. Therefore, minimizing human interference and ensuring suitable habitats at specific periods could facilitate the maintenance of waterbird diversity.
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Kendrick, Michael R., and Alexander D. Huryn. "Ephemeral wetlands as significant habitat for threatened crayfish in Alabama, USA." Freshwater Crayfish 21, no. 1 (December 31, 2015): 147–52. http://dx.doi.org/10.5869/fc.2015.v21-1.147.
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Abstract While ephemeral wetlands contribute significantly to regional freshwater biodiversity, their role in supporting threatened and imperiled species of crayfish is not widely recognized. As the center of global crayfish biodiversity, the southeastern United States (US), and the state of Alabama (AL) in particular, are important focal areas where information is needed to develop understanding of habitat constraints determining the distributions of crayfish species. To this end, we documented crayfish species associated with ephemeral wetlands and associated wetland habitats that have been traditionally under sampled. Fifteen species of crayfish were documented among 96 survey sites. This assemblage included three Alabama state-listed Priority 1 species [Cambarellus diminutus Hobbs, Fallicambarus burrisi Fitzpatrick, Procambarus viaeviridis (Faxon)] and five Priority 2 species [Hobbseus prominens (Hobbs), Orconectes lancifer (Hagan), Procambarus evermanni (Faxon), P. leconti (Hagan), P. marthae Hobbs]. An undescribed species of Cambarellus (“sp. A”) was also documented, and will presumably be eventually designated a Priority 1 species in Alabama due to its restricted distribution and apparent endemism. Ten species of crayfish were documented from ephemeral wetlands, including four Priority 1 and 2 species [Cambarellus sp. A (presumed Priority 1 species), H. prominens, P. marthae, P. viaeviridis]. Most populations of Priority 1 and 2 species we documented are within the 100-year floodplain of the Black Warrior River. Ephemeral wetlands and associated wetland habitats within the floodplains of large rivers thus appear to be vital habitat for threatened and imperiled crayfish in Alabama. Our results suggest that future crayfish surveys should include sampling of these important but often overlooked habitats.
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Naimo, Teresa J., James G. Wiener, W. Gregory Cope, and Nicolas S. Bloom. "Bioavailability of sediment-associated mercury toHexageniamayflies in a contaminated floodplain river." Canadian Journal of Fisheries and Aquatic Sciences 57, no. 5 (May 1, 2000): 1092–102. http://dx.doi.org/10.1139/f00-043.
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We examined the bioavailability of mercury in sediments from the contaminated Sudbury River (Massachusetts, U.S.A.). Mayfly nymphs (Hexagenia) were exposed in four 21-day bioaccumulation tests to contaminated and reference sediments (treatments) from reservoirs, flowing reaches, palustrine wetlands, and a riverine lake. Mean total mercury (ΣHg) ranged from 880 to 22 059 ng·g dry weight-1in contaminated sediments and from 90 to 272 ng·g-1in reference sediments. Mean final concentrations of methyl mercury (MeHg) in test water were greatest (8-47 ng Hg·L-1) in treatments with contaminated wetland sediments, which had mean ΣHg ranging from 1200 to 2562 ng·g-1. In mayflies, final mean concentrations of MeHg were highest in treatments with contaminated wetland sediments (122-183 ng Hg·g-1), intermediate in treatments with contaminated sediments from reservoirs, flowing reaches, and a riverine lake (75-127 ng Hg·g-1), and lowest in treatments with reference sediments (32-41 ng Hg·g-1). We conclude that the potential entry of MeHg into the benthic food chain was greater in contaminated palustrine wetlands than in the contaminated reservoirs, which had the most contaminated sediments.
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Kelleway, Jeff, Debashish Mazumder, G. Glenn Wilson, Neil Saintilan, Lisa Knowles, Jordan Iles, and Tsuyoshi Kobayashi. "Trophic structure of benthic resources and consumers varies across a regulated floodplain wetland." Marine and Freshwater Research 61, no. 4 (2010): 430. http://dx.doi.org/10.1071/mf09113.
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Riverine food webs are often laterally disconnected (i.e. between watercourses) in regulated floodplain wetlands for prolonged periods. We compared the trophic structure of benthic resources and consumers (crustaceans and fish) of the three watercourses in a regulated floodplain wetland (the Gwydir Wetlands, Australia) that shared the same source water but were laterally disconnected. The crustaceans Cherax destructor (yabby), Macrobrachium australiense (freshwater prawn), the exotic fish Cyprinus carpio (European carp) and Carassius auratus (goldfish) showed significantly different δ13C values among the watercourses, suggesting spatial differences in primary carbon sources. Trophic positions were estimated by using δ15N values of benthic organic matter as the base of the food web in each watercourse. The estimated trophic positions and gut contents showed differences in trophic positions and feeding behaviours of consumers between watercourses, in particular for Melanotaenia fluviatilis (Murray–Darling rainbowfish) and M. australiense. Our findings suggest that the observed spatial variation in trophic structure appears to be largely related to the spatial differences in the extent and type of riparian vegetation (i.e. allochthonous carbon source) across the floodplain that most likely constituted part of the benthic resources.
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Bullock, A., and M. Acreman. "The role of wetlands in the hydrological cycle." Hydrology and Earth System Sciences 7, no. 3 (June 30, 2003): 358–89. http://dx.doi.org/10.5194/hess-7-358-2003.
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Abstract. It is widely accepted that wetlands have a significant influence on the hydrological cycle. Wetlands have therefore become important elements in water management policy at national, regional and international level. There are many examples where wetlands reduce floods, recharge groundwater or augment low flows. Less recognised are the many examples where wetlands increase floods, act as a barrier to recharge, or reduce low flows. This paper presents a database of 439 published statements on the water quantity functions of wetlands from 169 studies worldwide. This establishes a benchmark of the aggregated knowledge of wetland influences upon downstream river flows and groundwater aquifers. Emphasis is placed on hydrological functions relating to gross water balance, groundwater recharge, base flow and low flows, flood response and river flow variability. The functional statements are structured according to wetland hydrological type and the manner in which functional conclusions have been drawn. A synthesis of functional statements establishes the balance of scientific evidence for particular hydrological measures. The evidence reveals strong concurrence for some hydrological measures for certain wetland types. For other hydrological measures, there is diversity of functions for apparently similar wetlands. The balance of scientific evidence that emerges gives only limited support to the generalised model of flood control, recharge promotion and flow maintenance by wetlands portrayed throughout the 1990s as one component of the basis for wetland policy formulation. That support is confined largely to floodplain wetlands, while many other wetland types perform alternate functions – partly or fully. This paper provides the first step towards a more scientifically defensible functional assessment system. Keywords: wetlands, hydrological functions, flood reduction, groundwater recharge, low flows, evaporation
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Lamontagne, S., W. S. Hicks, R. W. Fitzpatrick, and S. Rogers. "Sulfidic materials in dryland river wetlands." Marine and Freshwater Research 57, no. 8 (2006): 775. http://dx.doi.org/10.1071/mf06057.
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Due to a combination of river regulation, dryland salinity and irrigation return, lower River Murray floodplains (Australia) and associated wetlands are undergoing salinisation. It was hypothesised that salinisation would provide suitable conditions for the accumulation of sulfidic materials (soils and sediments enriched in sulfides, such as pyrite) in these wetlands. A survey of nine floodplain wetlands representing a salinity gradient from fresh to hypersaline determined that surface sediment sulfide concentrations varied from <0.05% to ~1%. Saline and permanently flooded wetlands tended to have greater sulfide concentrations than freshwater ones or those with more regular wetting–drying regimes. The acidification risk associated with the sulfidic materials was evaluated using field peroxide oxidations tests and laboratory measurements of net acid generation potential. Although sulfide concentration was elevated in many wetlands, the acidification risk was low because of elevated carbonate concentration (up to 30% as CaCO3) in the sediments. One exception was Bottle Bend Lagoon (New South Wales), which had acidified during a draw-down event in 2002 and was found to have both actual and potential acid sulfate soils at the time of the survey (2003). Potential acid sulfate soils also occurred locally in the hypersaline Loveday Disposal Basin. The other environmental risks associated with sulfidic materials could not be reliably evaluated because no guideline exists to assess them. These include the deoxygenation risk following sediment resuspension and the generation of foul odours during drying events. The remediation of wetland salinity in the Murray–Darling Basin will require that the risks associated with disturbing sulfidic materials during management actions be evaluated.