Flood Regime Research Articles

Re-Thinking Ecological Flow in Romania: A Sustainable Approach to Water Management for a Healthier Environment

Water resources and aquatic ecosystems are facing significant threats due to unsustainable water management practices. To address this challenge in Romania, a sustainable approach to water management is necessary, re-thinking ecological flow. This article proposes a re-thinking of the current approach to ecological flow in Romania by advocating for a more holistic and integrated approach considering environmental factors. The objective of the article was to present a methodology for the establishment of ecological flow that took into account the natural variability of flows. Four ecological flow values related to flood, high-water, medium-water, and low-water hydrological regimes were defined. To establish them, the duration curve of average daily flows was used in conjunction with hydromorphological and biological indicators. The proposed methodology was applied and compared to the existing methodology for the Uz river developed with hydropower use. The methodology represents a transition from the anthropocentric perspective to the sustainability perspective. The proposed methodology is easy to apply, with rigorously defined hydrological, hydraulic, and biological criteria. This research was conducted within the Hydrotechnical Faculty to refine the Romanian legislation regarding the improvement of the ecological status of all rivers.

Holocene climatic controls on flooding regime along the Ussuri River in Northeast Asia

Knowledge of the long-term flooding response to climatic changes is critical for probing the flooding future in an oncoming warmer world. In this paper, three well-dated wetland sedimentary cores with high-resolution grain-size records were employed to reconstruct the historical flooding regime along the Ussuri River during the past 7000 years. The results show that five flooding-prone intervals marked by increased mean rates of sand-fraction accumulation occurred at 6.4–5.9 ka BP, 5.5–5.1 ka BP, 4.6–3.1 ka BP, 2.3–1.8 ka BP, and 0.5–0 ka BP, respectively. These intervals are generally consistent with the higher mean annual precipitation controlled by the strengthened East Asian summer monsoon which has been widely documented in geological records across the monsoonal regions of East Asia. Considering the prevalent monsoonal climate along the modern Ussuri River, we suggest that the regional flooding evolution during the Holocene Epoch should be generally controlled by the East Asian summer monsoon circulation which was initially linked to the ENSO activities in the tropical Pacific Ocean. While for the last interval spanning 0.5–0 ka BP, human influence, compared with the long-serving climatic controls, has played a more critical role in driving the regional flooding regime.

Environmental and spatial determinants of fish community structure in an Afro‐tropical river ecosystem

AbstractWe investigated the relative influence of local environmental and spatial factors in structuring the community composition of fish at 15 sampling sites along the longitudinal gradient of the Lower Niger River Basin (LNRB) in dry and rainy seasons using distance‐based redundancy analysis and variation partitioning analysis. We collected a total of 3807 fish specimens representing 42 species. Our result indicated that the fish community composition differed between the upper and lower regions of the river. The communities in the upper region is influenced by high‐nutrient concentrations, while downstream sites were characterized by high concentrations of suspended solids. Variation partitioning revealed higher contributions of spatial than environmental predictors on fish community composition, with a higher total predicted variance in dry season. The variations in the community composition between upper and lower region may be attributable to the differences in the nature of anthropogenic activities within the regions, which influenced the local conditions differently. Differences in flow dynamics between upper and lower regions as attributable to black and white floods in the LNRB modify the connectivity between sites. Dispersal among sites may be more limited downstream than in the upper region, particularly in the dry season, because damming in the upper region also interrupts the natural flood regime such that there are low water levels in the lower region, which spatially isolate fish communities at certain sampling sites. The relatively higher total predicted variance during dry season may be attributable to the temporal differences in abiotic conditions between sites, which may have influenced site level community composition and abundance differently.

Spatial Variability of Topsoil Properties on a Semi-Arid Floodplain

This study relates the spatial heterogeneity (or patterning) of geochemical elements in the topsoil of a semi-arid floodplain/hillslope system in north-eastern Australia to vegetation distribution and rates of flood inundation. A total of 540 topsoil samples were collected from six flood frequency zones, ranging from a frequently flooded area (RI = 1:1–2 yrs) to two zones that have not flooded in living memory (RI > 50 yrs). Within each zone, topsoil samples were collected from both vegetated and non-vegetated surfaces, and each sample was analysed for 26 parameters. A combination of multi- and univariate analyses reveals that vegetation is an important contributor to topsoil heterogeneity. In zones subject to relatively frequent flooding, the spatial distribution of parameters in the topsoil is greatly influenced by the movement of water, with vegetation acting as a sink rather than a source. However, as floods become increasingly rare, distinct resource-rich units become evident in the topsoil beneath the vegetation. These findings indicate that topsoils in semi-arid floodplains are altered when their natural flooding regimes are reduced, beginning to approximate hillslopes when flood frequencies exceed 1-in-7 to 10 years. This points to the need for frequent flood (overbank) releases that are able to cover the 1-in-20-year floodplain to maintain the character of the soils and support vegetation growth in these environments.

Millennial-scale variability of water supply, vegetation and fire activity on a tropical wetland in central Brazil

The Pandeiros wetland is a tropical wetland located in the ecotone between the Cerrado and the Caatinga, in central Brazil. It has a key ecological importance for vegetation biodiversity, hydrological cycles, fauna reproduction and feeding, and for local human populations. Here, we investigate millennial-scale variability of water supply, vegetation structure and fire activity in the Pandeiros wetland during the Late Holocene and discuss forcing mechanisms that affected flooding, vegetation cover and fire regime within this fragile ecosystem. Our study is based on the previously studied pollen record of the Pandeiros palm swamp and on new charcoal analyses of two sediment cores that cover the last 4500 cal years, and their comparison to modern pollen and to available paleoclimatic data. Our results show that both local rainfall at the Pandeiros River basin and southern rainfall at the upper São Francisco River were important in maintaining water supply for the Pandeiros wetland during the last millennia. Our data also suggest that during Late Holocene the arboreal cover declined in the Cerrado of the Pandeiros Basin, an opposite trend to that observed in the wetter Cerrado-Atlantic Forest ecotone. We propose that increasing summer insolation in Southern Hemisphere was an important factor in maintaining low arboreal cover and open savanna vegetation on the drier areas around the Pandeiros wetland. Regarding fire activity, we suggest that until around 2600 cal yr BP, climate conditions were the most important driver of fire activity, in which drier conditions favored the intensification of fire, whereas subsequently, anthropic activities appear to have become an important fire inducer. Our findings highlight the multiple environmental aspects that have influenced the Pandeiros wetland history during the last four thousand years, including monsoon variability, insolation variation and human occupation.

The Effect of Flood Regime on Water Quality and Plankton Distribution in Bosso Area, Minna, Niger State

Flooding endangers lives and property, and it can lead to surface water pollution, reducing access to potable water and destroying wildlife habitats. This study investigated the effect of flood on water quality and plankton in two selected water bodies in within Minna Metropolis, Niger state, Nigeria. Water samples were collected for physicochemical parameters and plankton identification using standard methods and procedures. Samples were collected for a period of six (6) months (April to September 2021). The result of the physiochemical parameters showed temperature (26.0-28.5°C), flow velocity (0.23 to 0.26 m/s), dissolved oxygen (6.4-10.0mg/l), turbidity (30-240 NTU), pH (7.21-7.53), TSS (0.04-0.04), electrical conductivity (69-228 µS/cm) and total dissolved solid (60-220 mg/l). Most of these parameters were within the WHO permissible limits. From all the parameters measured, temperature, DO, pH and TSS showed no significance difference (p>0.05) between the water bodies while turbidity, total alkalinity, electrical conductivity and total dissolved solid exhibit significant difference (p<0.05) between the water bodies with Fadipe Pool recording higher values in most of the parameters. A total of 12 phytoplankton species were identified comprising of 3 families which are Bacillariophyceae (2), Chlorophyceae (6), and Cyanophyceae (4). For the zooplankton, a total of 11 species are made up of 3 taxa which are Cladocera (4), Copepoda (2), and Rotifera (5). In this study, several plankton species that serve as indicator organisms were identified which is indication of a disturbed water bodies.

Downstream Distribution and Postdepositional Mobilization of Cadmium in Alluvial Soils

The geochemical signature in alluvial soils is a witness of human activities that took place in a river catchment. Sampling of alluvial soils at depth, in combination with information on sedimentological history and age of samples, may even allow to reconstruct the pollution history of the river basin. In the present study, data on alluvial soils contaminated by a major pollution source were analyzed, with special attention for these soils as an archive for information on the pollution history of a river/river catchment, and on the postdepositional downward migration of metal(loid)s in the alluvial soils. Besides the lateral variation of soil properties and metal(loid) concentrations in the alluvial soils, the vertical distribution of metal(loid)s in soil profiles, as well as the evolution of soil composition in relation to the distance from the river, was addressed. The postdepositional mobilization of Cd was evaluated in a fine-scale sampled alluvial soil core, by comparing data from 137Cs dating with data about the Cd emissions through time and by using leaching tests to calculate the downward migration of Cd. A substantial amount of Cd could leach from superficial to deeper soil layers. Therefore, the low-resolution (cm-scale) sampling of the alluvial soil was not reliable to reconstruct the pollution history of the river catchment, because the elevated chloride-concentrations in the river water increased the downward leaching of Cd through the formation of chloro-complexes. Moreover, the variability in flooding and sedimentation regimes along the river resulted in a heterogeneous composition of the alluvial soils, allowing very large differences in metal(loid) concentrations in places only a few meters apart.

Microscopic food webs under vanishing winters

Climate warming is affecting winter conditions in temperate regions, causing rapid changes in the formation and maintenance of snow and ice cover. However, little is known about planktonic and epixylon communities in dynamic river-floodplain systems in winter, as previous research has focused on the spring and summer „growing seasons“. Therefore, changes in the diversity, abundance, and functional groups of phytoplankton, zooplankton, and epixylon in the Danube floodplain (Kopački Rit Nature Park) were studied. In winter (January - March), water surfaces were covered only by a thin and patchy ice cover. Plankton and epixylon were diverse and abundant, and the changes in functional groups described the conditions prevailing in the studied waters well. The relatively stable conditions at the beginning of the study favoured the development of phytoplankton (diatoms, cryptophytes, ochrophytes), and epixylic taxa (diatoms, cyanobacteria) both belong to functional groups characteristic of shallow, turbid waters. Intense flooding and high grazing pressure reduced phytoplankton and epixylon abundance. The zooplankton community changed mainly due to the flood regime, subsequent nutrient loading, and food sources. Microfilter-feeding rotifers depended on phytoplankton, whereas microphytes that developed on epixylon were more important to the community for larger rotifers. The results suggest that further studies of floodplain winter communities are needed to understand better and predict floodplain ecology in future years.

Flooding duration affects the temperature sensitivity of soil extracellular enzyme activities in a lakeshore wetland in Poyang Lake, China

Extracellular enzymes play central roles in the biogeochemical cycles in wetland ecosystems. Their activities are strongly impacted by hydrothermal conditions. Under the ongoing global change, many studies reported the individual effects of flooding and warming on extracellular enzyme activities, however, few researches investigated their interactive effects. Therefore, the current study aims to determine the responses of extracellular enzyme activities to warming in wetland soils under divergent flooding regimes. We investigated the temperature sensitivity of seven extracellular enzymes related to carbon (α-glucosidase, AG; β-glucosidase, BG; cellobiohydrolase, CBH; β-xylosidase, XYL), nitrogen (β-N-acetyl -glucosaminidase, NAG; leucine aminopeptidase, LAP), and phosphorus (Phosphatase, PHOS) cycling along the flooding duration gradient in a lakeshore wetland of Poyang Lake, China. The Q10 value, calculated using a temperature gradient (10, 15, 20, 25, and 30 °C), was adopted to represent the temperature sensitivity. The average Q10 values of AG, BG, CBH, XYL, NAG, LAP, and PHOS in the lakeshore wetland were 2.75 ± 0.76, 2.91 ± 0.69, 3.34 ± 0.75, 3.01 ± 0.69, 3.02 ± 1.11, 2.21 ± 0.39, and 3.33 ± 0.72, respectively. The Q10 values of all the seven soil extracellular enzymes significantly and positively correlated with flooding duration. The Q10 values of NAG, AG and BG were more sensitive to the changes in flooding duration than other enzymes. The Q10 values of the carbon, nitrogen, and phosphorus-related enzymes were mainly determined by flooding duration, pH, clay, and substrate quality. Flooding duration was the most dominant driver for the Q10 of BG, XYL, NAG, LAP, and PHOS. In contrast, the Q10 values of AG and CBH were primarily affected by pH and clay content, respectively. This study indicated that flooding regime was a key factor regulating soil biogeochemical processes of wetland ecosystems under global warming.

How Homeownership, Race, and Social Connections Influence Flood Preparedness Measures: Evidence from 2 Small U.S. Cities

ABSTRACT Climate change and changing built environments are changing flooding regimes. Since flood management policies often rely on household preparedness, understanding what factors shape household flood preparedness measures is imperative. We focus on three dimensions: race, participation in local organizations, and homeownership as moderated by flood experience. With survey data from two small riverside cities in the northeastern United States, we examine how these factors affect the adoption of low-cost and high-cost flood protection measures. We find that effects of flood experience vary across renters, mortgage-holding homeowners, and homeowners without mortgages, and patterns differ for low-cost and high-cost measures. In regression models that control for other factors, white residents take more low-cost measures than nonwhite residents. Among households in locations with greater flood risk, nonwhite households take more high-cost flood protection measures. Community group participation has a positive effect on low-cost protective measures, and the effect is more pronounced among floodplain residents. Processes related to both race and homeownership shape people’s access to flood preparedness measures. Understanding patterns of household flood protection may help in identifying leverage points for ameliorating disparities in flood vulnerability across communities.

Transformation of Volga river runoff in multiyear aspect

The article describes in detail all the most significant components of the hydrological regime in the lower reaches of the Volga. As a result of the regulation of the Volga runoff by the Volgograd hydroelectric dam in 1958, the ecological conditions of natural reproduction of fish changed significantly: the areas of spawning grounds decreased, the hydrological regime was violated, which led to deformation of the spring flood regime, intra-annual redistribution of runoff. Their size is of fundamental importance for the fisheries of the Volga-Caspian basin. Attention is drawn to the deep deformation of all flood indicators that occurred after the regulation of the Volga runoff on the Lower Volga, while in the worse direction for the reproduction of aquatic biological resources. The process of degradation of aquatic biological resources of the Volga-Caspian reflects the lack of the minimum hydroecological conditions necessary to ensure the formation of resilient juvenile fish in the process of their natural reproduction in the overwhelming number of years. The modern operation of the Volga-Kama cascade of reservoirs does not meet the requirements of the Volga-Caspian fisheries. There is a tendency to increase intraannual redistribution of runoff, due to high winter releases of water into the lower reaches of the Volgograd hydroelectric complex and low spring releases. The system of management and intersectoral distribution of water resources during the flood does not currently meet the necessary hydroecological conditions under which it is possible to form resilient fish offspring and, as a consequence, preserve and increase stocks of the most valuable commercial fish species. The main reasons for the decrease in water reserves are determined by the regulation of the Volga runoff and as a result of this reduction in the volume of water supply to the lower reaches of the Volgograd hydroelectric complex. Especially this negative manifestation of a sharp deterioration in the flooding of spawning grounds occurs in low-water years, when the priority is to fill the reservoirs of the cascade to a normal retaining level in order to ensure the generation of hydroelectric power during the inter-war period (summer, autumn, winter), the operation of water transport, the implementation of water intake for irrigation, utility purposes, etc.

Adaptive capacity of high- and low dyke farmers to hydrological changes in the Vietnamese Mekong delta

This research assesses the adaptive capacity of farmers in the Vietnamese Mekong Delta's floodplains (VMD) with respect to hydrological changes. Currently, climate change and socio-economic developments induce extreme- and diminishing floods, which in turn increase farmers' vulnerability. This research assesses farmers' adaptive capacity to hydrological changes using two prevalent farming systems: high dykes featuring triple-crop rice farming and low dykes where fields are left fallow during the flood season. We examine (1) farmers' perceptions on a changing flood regime and their current vulnerabilities and (2) farmers' adaptive capacity through five sustainability capitals. Methods include a literature review and qualitative interviews with farmers. Results show that extreme floods are becoming less frequent and damaging, depending on arrival time, depth, residence time, and flow velocity. In extreme floods, farmers' adaptive capacity is generally strong, and only low dyke farmers experience damage. As for diminishing floods, which is an emerging phenomenon, the overall adaptive capacity of farmers is remarkably weaker and varies between high- and low dyke farmers. Financial capital is lower for low dyke farmers due to their double-crop rice system, and natural capital is low for both farmer groups due to a decrease in soil- and water quality, affecting yields and increasing investment costs. Farmers also struggle with an unstable rice market due to strong fluctuating prices for seeds, fertilizers, and other inputs. We conclude that both high- and low dyke farmers have to cope with new challenges, including fluctuating flood patterns and the depletion of natural resources. Increasing farmers resilience should focus on exploring better crop varieties, adjusting crop calendars, and shifting to less water-intensive crops.

Iron plaque crystallinity, heavy metal toxicity, and metal translocation in Kandelia obovata seedlings as altered by an iron-reducing bacterium under different flooding regimes

Iron plaque crystallinity, heavy metal toxicity, and metal translocation in Kandelia obovata seedlings as altered by an iron-reducing bacterium under different flooding regimes

Cover Image

EcosphereVolume 14, Issue 2 e4117 COVER IMAGEOpen Access Cover Image First published: 07 February 2023 https://doi.org/10.1002/ecs2.4117AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract COVER PHOTO: Riparian corridors support mosaics of highly productive vegetation and barren surfaces that are dynamically linked to disturbance and successional processes. Retrospective comparisons of high-resolution imagery by Frost et al. (Ecosphere, Volume 14, Issue 1, Article e4344; doi: 10.1002/ecs2.4344) reveal that the cover of riparian vegetation such as feltleaf willow (Salix alaxensis) and dwarf fireweed (Chamerion latifolium), pictured here along upper Trail Creek in Alaska's Wrangell/St. Elias National Park & Preserve, have increased since the early 1980s along 12 widely separated rivers in national parklands of Interior Alaska. Widespread “greening” of these floodplains has occurred against a backdrop of changing climate, seasonal discharge and flood regime, and permafrost thaw in subarctic watersheds, with implications for ecosystem function and services. Increases in tall shrub cover have been disproportionately high in the upper portions of streams above the elevational treeline, consistent with recent shrubification in Arctic tundra ecosystems. Photo credit: Gerald V. Frost. Volume14, Issue2February 2023e4117 RelatedInformation

Hydrodynamic considerations for improving the design/evaluation of over-topped bridge decks during extreme floods

Flow over an Iranian bridge deck is studied under an actual extreme flood event happening similarly nowadays in many countries due to climate change. Rigorous transient fluid-structure interaction analyses using the realizable k-ε turbulence model and the VOF Method are conducted. Geotechnical and abutments damages are neglected. Water surface profiles, velocity vectors, and hydrodynamic coefficients are determined. Based on the latest hydrological regime, particularly in supercritical flows, the results are partially compared against the latest advanced design codes, to evaluate the performance of their hydrodynamic and hydraulic provisions in similar incidents. It was acknowledged that the flood loads recommended by the Federal Highway Administration (FHWA) are fairly acceptable, Eurocode-1 predicts them rather accurately but not in extreme cases, and the Australian Standard (AS-5100.2) is less effective due to over-estimation of the hydrodynamic loads. Instead, the latter offers comprehensive user-defined hydraulic conditions. Furthermore, upon gradual rise of the water level to thrice the deck height, bridge stability is found to be at risk due to highly turbulent states. It is recommended that due to such threats, re-evaluation of flood regime, as well as its distinct hydrodynamic properties have to be accounted for, when evaluating existing bridges or designing new ones.

Climate related changes to flood regimes show an increasing rainfall influence

Climate change can result in changes to floods and flood regimes, but the relationship between floods and climate change is complex and poorly understood. The flood regime influences the nature, severity, and timing of flood events for any watershed. Flood regimes should be viewed as a continuum with completely nival (snowmelt-driven) watersheds at one end of the continuum and purely pluvial (rainfall-driven) watersheds at the other. Flood regimes are important for the operation of flood defenses and to better understand how changes in the flood regime can affect the magnitude of flood events. Data from 46 long term streamflow gauging stations from reference hydrologic networks (RHNs) in Canada (23) and the US (23), are examined to detect changes that have occurred, or are continuing to occur, in flood regimes from watersheds responding only to climate variations and changes. Peaks over Threshold (POT) flood events are used to investigate changes in the timing of flood events. Seasonality measures, using circular statistics, illustrate changes in the nature of the flood regime based on changes in the timing and regularity of flood threshold exceedences. A nival fraction is determined for each watershed and for each year based on a clustering of the flood events into two groups, representing nival and pluvial events. Changes to the flood regime over time, and based on annual temperature, are determined from logistic regression of the number of nival and pluvial events for each year. While strongly nival watersheds show no changes, roughly 15% of the stations exhibit significant changes that represent shifts towards the pluvial end of the flood regime continuum, which has implications for design flood estimation and the operation of flood control infrastructure.

Legacy archaeology: Aboriginal subsistence response to Holocene environmental changes using faunal evidence from archaeological sites on the Lower Murray, South Australia

Ngaut Ngaut (Devon Downs) and Tungawa (Fromm’s Landing) 2 and 6 are located in the Gorge Section of the Lower Murray River. They were excavated more than 60 years ago. Unusually, they preserved fauna over the 6000 or 7000 years of occupation. Assessing this record, it is concluded that Aboriginal agents were responsible for the middens in these rockshelters. Following this, Ngaut Ngaut and the Tungawa sites are compared in terms of their dating, stratigraphy and changes in the fauna through time. While the majority of species are present throughout at all three sites, there are shifts in the number of animals in concert with Holocene environmental changes. After 3000 BP, the trend is to increased attention being given to resources from the riparian and river zones and away from the dryland Murray Plains. An increase in shellfish and the presence of crayfish gastroliths support this contention. Nearby Tartanga Island provides a record of Holocene sedimentary changes in the Murray River associated with altered sea level and flood regimes, particularly the deposition of the Monoman and Coonambidgal formations. The latter creating a landscape of highly productive swamps and backwaters. The information from these legacy excavations supports the conclusion that a shift in the locus of Aboriginal hunting and gathering activities accompanied mid- and late-Holocene environmental changes on the Lower Murray River.

Flooding tolerance in Rice: adaptive mechanism and marker-assisted selection breeding approaches.

Natural and man-made ecosystems worldwide are subjected to flooding, which is a form of environmental stress. Genetic variability in the plant response to flooding involves variations in metabolism, architecture, and elongation development that are related with a low oxygen escape strategy and an opposing quiescence scheme that enables prolonged submergence endurance. Flooding is typically associated with a decrease in O2 in the cells, which is especially severe when photosynthesis is absent or limited, leading to significant annual yield losses globally. Over the past two decades, considerable advancements have been made in understanding of mechanisms of rice adaptation and tolerance to flooding/submergence. The mapping and identification of Sub1 QTL have led to the development of marker-assisted selection (MAS) breeding approach to improve flooding-tolerant rice varieties in submergence-prone ecosystems. The Sub1 incorporated in rice varieties showed tolerance during flash flood, but not during stagnant conditions. Hence, gene pyramiding techniques can be applied to combine/stack multiple resistant genes for developing flood-resilient rice varieties for different types of flooding stresses. This review contains an update on the latest advances in understanding the molecular mechanisms, metabolic adaptions, and genetic factors governing rice flooding tolerance. A better understanding of molecular genetics and adaptation mechanisms that enhance flood-tolerant varieties under different flooding regimes was also discussed.

Flood regimes alter the role of landform and topographic constraint on functional diversity of floodplain forests

Understanding patterns of species coexistence is a fundamental challenge in ecology. The physical environment is believed to play an important role, influencing patterns of dispersal and biotic interactions across space and time. Floodplain forest species are presumed to interact strongly with their environment, as evidenced by pronounced spatial variation in forest composition associated with flood‐driven abiotic constraints. Questions of how, and to what degree, fine‐scale heterogeneity interacts with broad‐scale hydrogeomorphology to influence patterns of functional composition remain unresolved. We examined how functional diversity (i.e. richness and range of functional traits) and ecological strategies (i.e. functional trait combinations) of floodplain forest communities varied across regional and local gradients of flooding in a northern temperate region of the United States of America. We found functional diversity of woody overstory species varied across hydrogeomorphic settings and that different settings altered associations between functional diversity and both the relative elevation above and proximity to rivers. Ecological strategies shifted over local gradients of relative elevation and distance to channel with different magnitudes and directions depending on the broader hydrogeomorphic context. We found evidence that interactions among flood regimes and landform position impose different levels of functional constraint. These results indicate patterns of community assembly are not easily discerned from landform type or position alone, but rather from filtering that operates and interacts with biota over multiple spatial scales. Our results imply that it is important to characterize flood dynamics in ways that can be clearly linked to ecological processes and that treatment of floodplain landforms as transferable units across river‐valley segments is problematic, even within a single basin.

A Complete Model for Mesh Pad Mist Eliminators in Oil and Gas Processing by Analogy with Distillation Packing

Summary Current models for pressure drop in mesh pads are not adequate for pressure drop critical applications and do not cover the flooding regime commonly encountered when mesh pads are used as a coalescer. In addition, these models do not predict the flooding capacity of mesh pads. Pressure drop and capacity models for mesh pads are presented and compared with literature experimental data for fluid systems ranging from atmospheric pressure to 85-bar natural gas. The experimental data were successfully correlated from the region of countercurrent flow through to flooding of the mesh pads. The model captures, quantitatively, the pressure drop and liquid holdup in mesh pads as well as predicting the flood point of the mesh. When combined with a separation performance method, flooding in layered mesh pads can also be predicted. The model covers both conventional and co-knit mesh pads and can be adapted to other packing geometries, requiring only dry pressure drop data.