Experimental Flooding Research Articles

Ecosystem effects of environmental flows: modelling and experimental floods in a dryland river

Summary1. Successful environmental flow prescriptions require an accurate understanding of the linkages among flow events, geomorphic processes and biotic responses. We describe models and results from experimental flow releases associated with an environmental flow program on the Bill Williams River (BWR), Arizona, in arid to semiarid western U.S.A.2. Two general approaches for improving knowledge and predictions of ecological responses to environmental flows are: (1) coupling physical system models to ecological responses and (2) clarifying empirical relationships between flow and ecological responses through implementation and monitoring of experimental flow releases.3. We modelled the BWR physical system using: (1) a reservoir operations model to simulate reservoir releases and reservoir water levels and estimate flow through the river system under a range of scenarios, (2) one‐ and two‐dimensional river hydraulics models to estimate stage–discharge relationships at the whole‐river and local scales, respectively, and (3) a groundwater model to estimate surface‐ and groundwater interactions in a large, alluvial valley on the BWR where surface flow is frequently absent.4. An example of a coupled, hydrology‐ecology model is the Ecosystems Function Model, which we used to link a one‐dimensional hydraulic model with riparian tree seedling establishment requirements to produce spatially explicit predictions of seedling recruitment locations in a Geographic Information System. We also quantified the effects of small experimental floods on the differential mortality of native and exotic riparian trees, on beaver dam integrity and distribution, and on the dynamics of differentially flow‐adapted benthic macroinvertebrate groups.5. Results of model applications and experimental flow releases are contributing to adaptive flow management on the BWR and to the development of regional environmental flow standards. General themes that emerged from our work include the importance of response thresholds, which are commonly driven by geomorphic thresholds or mediated by geomorphic processes, and the importance of spatial and temporal variation in the effects of flows on ecosystems, which can result from factors such as longitudinal complexity and ecohydrological feedbacks.

Water and salt balance of a saline water disposal basin during an experimental flooding and drying cycle (Loveday Disposal Basin, Australia)

AbstractSaline irrigation drainage water along the semi‐arid lower River Murray is often disposed of into evaporation basins to prevent contamination of downstream water supplies. These evaporation basins are often former ephemeral floodplain wetlands that have now become extremely ecologically degraded due to high soil and water salinity. An experimental flooding with freshwater was conducted at Loveday Disposal Basin in 2006 to evaluate the environmental benefits of periodic flooding with freshwater. The water and salt balances of the permanent North Basin and ephemeral South Basin during the experiment were evaluated using a combination of hydrometric techniques and trends for salinity and the stable isotopes of water. Filling of the basins (with freshwater from the River Murray) decreased salinity (as total dissolved solids) from approximately 60 to 9 g l−1. Once flooding was completed, water level in both basins receded rapidly and then within 5 months they had re‐salinised to pre‐treatment levels. The main re‐salinisation mechanism was greater evaporative loss induced by the large increase in wetted surface area after flooding, especially in the shallower South Basin. Dissolution of evaporites was not a source of salt to the basins because halite remained undersaturated at all times, but minor quantities of Ca2+ and SO42− were gained from gypsum and carbonate dissolution. The salt mass stored in South Basin surface water increased during flooding and early after flooding, suggesting a significant salt input from the flooded soils. Because of large salt stores in surrounding soils and groundwater, ongoing saline groundwater discharge, and large evaporative losses, periodic flooding alone brings limited environmental benefits (that is, conditions favourable to freshwater organisms) to floodplain disposal basins. However, flooding deeper disposal basins during winter will minimise evaporative losses and increase the length of the freshening period. Copyright © 2009 John Wiley & Sons, Ltd.

Flow Visualization of Waterflooding with Horizontal and Vertical Wells

This article presents an experimental and numerical study of the water-flooding process with different horizontal and vertical well configurations using flow visualization technique. The effect of horizontal wells on flood profile has been investigated by using two different well configurations, viz., horizontal injection-vertical production (HI-VP) and vertical injection-horizontal production (VI-HP). The experimental results show that HI-VP configuration recovers more oil than VI-HP configuration. The commercial simulator, ECLIPSE, is used for simulating the flood profiles for these well configurations. A good agreement is observed with the experimental flood profiles. Further simulations are carried out with varied perforation lengths and well positions to find out the optimal well configuration for both HI-VP and VI-HP. Such flow visualization experiments can be used as a validation tool for numerical simulators.

Visiting the Methodological Aspects of Flooding Experiments: Quantitative Evidence from Agricultural and Ecophysiological Studies

AbstractPlant responses to flooding have been studied and reviewed extensively. However, the differences among the experimental procedures used to apply the flood that lead to such responses have never been explored. In this work, a database of 132 articles was created to quantify important methodological aspects of flooding experiments in crop and non‐crop species for the first time as well as to look for thematic gaps in our knowledge on flooding research. Results showed that the flood experiments were conducted differently for crop and non‐crop species, with two main distinctions: the duration of the flood and the consideration of competition among plants. For crop species, experimental flooding had a short duration of 16 days (ranging from 8 to 28 days for the 25th and 75th percentiles), while for non‐crop species, flooding was quite longer, nearly 45 days (ranging from 28 to 61.5 days). Also, 53 % of the examined experiments in crop species considered competition among plants in their experimental protocol, while only 20 % did so for non‐crop species. Regarding the topics least investigated within this area, in terms of both crop and non‐crop species, future investigation should focus on the effects of flooding on reproductive traits, mineral nutrition and the nitrogen fixation of plants. These results are discussed, along with their implications in terms of defining crucial aspects of the methodology of flooding experiments.

EXPERIMENTAL FLOODS CAUSE ECOSYSTEM REGIME SHIFT IN A REGULATED RIVER

Reservoirs have altered the flow regime of most rivers on the globe. To simulate the natural flow regime, experimental floods are being implemented on regulated rivers throughout the world to improve their ecological integrity. As a large-scale disturbance, the long-term sequential use of floods provides an excellent empirical approach to examine ecosystem regime shifts in rivers. This study evaluated the long-term effects of floods (15 floods over eight years) on a regulated river. We hypothesized that sequential floods over time would cause a regime shift in the ecosystem. The floods resulted in little change in the physicochemistry of the river, although particulate organic carbon and particulate phosphorus were lower after the floods. The floods eliminated moss cover on bed sediments within the first year of flooding and maintained low periphyton biomass and benthic organic matter after the third year of flooding. Organic matter in transport was reduced after the third year of flooding, although peaks were still observed during rain events due to tributary inputs and side slopes. The floods reduced macroinvertebrate richness and biomass after the first year of floods, but density was not reduced until the third year. The individual mass of invertebrates decreased by about one-half after the floods. Specific taxa displayed either a loss in abundance, or an increase in abundance, or an increase followed by a loss after the third year. The first three flood years were periods of nonequilibrium with coefficients of variation in all measured parameters increasing two to five times from those before the floods. Coefficients of variation decreased after the third year, although they were still higher than before the floods. Analysis of concordance using Kendall's W confirmed the temporal changes observed in macroinvertebrate assemblage structure. An assessment of individual flood effects showed that later floods had approximately 30% less effect on macroinvertebrates than early floods of similar magnitude, suggesting that the new assemblage structure is more resilient to flood disturbance. We conclude that the floods caused an ecosystem regime shift that took three years to unfold. Additional long-term changes or shifts are expected as new taxa colonize the river from other sources.

Experimental and Numerical Investigations of Waterflood Profiles with Different Well Configurations

Experimental and numerical investigations of a waterflooding process with three different well configurations, vertical injection–vertical production (VI–VP), vertical injection–horizontal production (VI–HP), and horizontal injection–horizontal production (HI–HP), are studied here in a two-dimensional visualization cell with wells placed inside the porous medium. Water and oil profiles are tracked by mixing colored dyes that are soluble in only one phase. Experimental initial oil saturation distribution is supplied to the simulator using colored dye distribution by the Matlab image processing tool. The water flood profiles obtained by simulation using ECLIPSE are in reasonable agreement with experimental results. It is observed from experimental flood profiles that irreducible (connate) water distribution has an effect on the waterflood movement. It is seen that draw-down created by a vertical well is felt on the flood profile from the beginning of the waterflooding whereas this is not the case with the horizontal well. It is also observed that in case of the VI–VP configuration, the relative swept area is more.

Crayfish and fish as bioturbators of streambed sediments: Assessing joint effects of species with different mechanistic abilities

Many studies illustrate that bioturbating animal species individually affect aquatic sediments through diverse mechanistic abilities, whereas assessments of joint effects of such species on sediments are relatively rare. Such joint effects have implications for real systems, in which different bioturbators coexist, but are difficult to predict for two reasons. First, they can be additive (being the sum of the individual effects of each species) or they can be positive or negative interactive (being greater or smaller than the sum of the individual effects). Second, if interactive, they can depend on biotic interactions that affect the bioturbating activities of the species and/or they can depend on physical interactions among bioturbator-induced sediment modifications. Using experimental streams, we assessed such joint effects on gravel–sand sediments for flow and sediment conditions preferred by barbel ( Barbus barbus) but also used by gudgeon ( Gobio gobio) and, in a second experiment, for flow and sediment conditions preferred by both male crayfish ( Orconectes limosus) and gudgeon. These species have different mechanistic abilities to affect gravel and/or sand in stream beds. In each experiment, we measured (i) the transport of gravel and sand at baseflow (during 12 experimental days); (ii) four sediment surface characteristics (after 12 d); and (iii) the critical shear stress ( τ c) causing incipient gravel and sand motion during experimental floods (after 12 d). Gudgeon contributed differently to the joint effects in the two experiments, which related to its individual weight, prevailing baseflow shear stress, sediment particle weight, and sediment mixture (availability of surface sand). Overall, the species pairs had predominantly negative interactive joint effects on the sediment variables assessed by us. Both a literature survey and observations during the experiments provided no evidence for direct biotic interactions between barbel and gudgeon or crayfish and gudgeon, so one would reasonably associate their negative interactive effects on the sediments with physical interactions among bioturbator-induced sediment surface modifications. Individually, each species reduced the percentage of sand in the surface layer and the surface algal cover to relatively low values so that the species pairs could not accomplish much greater joint effects on these variables, explaining their negative interactive effects on them. As algal cover particularly affected the τ c for gravel and sand, the negative interactive effects of the animals on this surface variable chained toward the τ c for the sediments, on which the species pairs also had negative interactive effects. Such chained negative interactive effects on sediment variables are seemingly a general pattern of joint bioturbator effects on aquatic sediments, i.e., the many so far described single-species effects should be smaller than their sum if the species coexists in nature.

Bottomland hardwood forest species responses to flooding regimes along an urbanization gradient

Urbanization alters stream hydrology, hence flooding frequency and duration in floodplain wetlands. Potential impacts include shifts in species composition and survival, making restoration and selection of wetland species difficult. Cephalanthus occidentalis, Fraxinus pennsylvanica, and Quercus shumardii seedlings were subjected to experimental flooding regimes typical of floodplain forests in rural and urban settings. Treatments included a rural flood regime with three 7-day floods, an Urban-short flood regime with six 4-day floods, and an Urban-long flood regime with six 10-day floods over a growing season. Specific responses, measured by stem length, leaf area, and leaf, stem, and root biomass, varied between species from different wetland indicator classes. C. occidentalis, a wetland obligate, was well adapted to both urban flooding regimes, whereas productivity of F. pennsylvanica, a facultative wetland species, and Q. shumardii, a facultative species, was significantly reduced by the Urban-long treatment. Growth rates also varied over time, indicating the importance of temporal flooding patterns on species productivity. Because urban flooding regimes directly and selectively alter species productivity, proper restoration methods in urbanizing environments should include species selection based on current and potential future hydrologic conditions and use of reference standards from reference sites subjected to similar urban hydrologic regimes.

Responses of twelve tree species common in Everglades tree islands to simulated hydrologic regimes

Twelve tree species common in Everglades tree islands were subjected to three hydrologic regimes under controlled conditions for 25 weeks and assessed for growth and physiological responses. Treatments representing high, low, and no flood were maintained in pools of water to mimic seasonal variation in water depths at different positions in tree islands. Soil inundation under the high flood treatment resulted in reduced tree growth (height, basal diameter, crown volume) that was more pronounced and occurred earlier in mesic forest species than in swamp forest species. Physiological responses differed less among species, although stomatal conductance was a better predictor of the effects of flood stress on growth than either relative water content or chlorophyll fluorescence (Fv/Fm). Some swamp species appeared to be better adapted to rising water levels than others; Annona glabra, Morella cerifera, and Salix caroliniana responded more positively to flooding, while Magnolia virginiana, Persea borbonia, Chrysobalanus icaco, and Ilex cassine were less flood-tolerant. The highest mortalities and lowest growth were observed in the five upland species: Bursera simaruba, Coccoloba diversifolia, Eugenia axillaris, Sideroxylon foetidissimum, and Simarouba glauca. Of these, Sideroxylon and Simarouba did not survive to the end of the study under the high flood treatment. The moist soil conditions simulated by the low flood treatment resulted in greater growth in all species compared to soil inundation under high flood, except for the most flood-tolerant (Annona, Morella, Salix). The arrangement of species according to their responses to experimental flooding roughly paralleled their spatial distribution in the tree islands. The gradient in species responses demonstrated in this experiment may help guide responsible water management and tree island restoration in the Everglades.

Ripple effect: Unforeseen applications of sand studies

Sand ripples and their deposits are playing a crucial role in unraveling the history of flowing water on Mars, conducting experimental floods to restore beaches in the Grand Canyon, and improving the ability to detect explosive mines buried beneath the seafloor. Even the visionary geologists who discovered the origins of ripples and ripple stratification could never have imagined these future applications of their work.Sand ripples formed by blowing wind and flowing water have been studied for almost 150 years. This article briefly reviews some key discoveries in understanding ripples, reviews three studies that are currently utilizing ripples, and illustrates how simple fundamental discoveries have unexpected practical applications.

Flow phenomena and flooding limitations in a phase transition extraction column

The flooding limitations of liquid–liquid countercurrent two-phase flow in a phase transition extraction (PTE) column were investigated both experimentally and theoretically. The solvents used in the PTE process are partially miscible and posses a critical point of miscibility. In the experiments, the effect of the settlers’ inclination on the onset of flooding in non-isothermal PTE column was investigated. It was found that flooding conditions in the column can be postponed by using off-horizontal settlers. This led to the development of a novel structure of a PTE column with improved throughputs. A model is suggested for predicting flooding conditions in the PTE column. It combines a recently developed two-fluid model with improved theory-based closure relations for laminar stratified flow, with a non-isothermal model for evaluating the composition in the mixing section and the internal streams in the column. The results of the combined model favorably predict the experimental flooding flow rates.

05/02817 Competition of gravity, capillary and viscous forces during drainage in a two-dimensional porous medium, a pore scale study

This paper reports new experimental and numerical results on miscible displacements in saturated, homogeneous five-spot bead-packed flow models. A series of experimental floods at a range of mobility ratios is presented which generates new data for unstable displacement processes. These data are presented up to 100% recovery and they include the following: the effluent concentrations and recovery profiles, in situ visualisation of the flow patterns and measurement of the pressure field. A comparable cycle of floods at mobility ratios of approximately M = 4,11 and 25 in a repacked five-spot system showed excellent reporducibility between tests. The volumetric displacement efficiencies compare very well with the published experimental data where this is available. The measurement of the pressure field is particularly novel and this information can be utilised in order to assess averaged (upscaled) models of viscous instability.A high-accuracy numerical method with third-order differencing for convection and second-order temporal differencing is proposed which is equivalent to an 11-point interpolation. The simulator treats the full velocity-dependent anisotropic diffusion/dispersion tensor and is validated by comparing numerical results with the analytical solution for incompressible radial flow. The numerical method has been used to simulate the experimental five-spot stable and unstable displacements. The simulation reproduces the experimental effluent concentrations, recovery performances and pressure drops very well and also matches the main features of the experimental finger evolution.The central novel contributions of this paper are that (i) a complete qualitative experimental data set, including novel pressure field measurements, has been obtained up to 100% recovery which can be used to validate theoretical models of viscous fingering in five-spot (almost) homogeneous systems; and (ii) a numerical scheme is presented which is capable of accurately simulating the flows characterised by instability and low levels of physical dispersion in this ‘difficult’ geometry.

Mechanisms of Riparian Cottonwood Decline Along Regulated Rivers

Decline of riparian forests has been attributed to hydrologic modifications to river flows. However, little is known about the physiological and structural adjustments of riparian forests subject to modified flow regimes, and the potential for forest restoration using historic flow regimes is poorly understood. In this paired river study, we compared hydrology, water relations, and forest structure in cottonwood-dominated floodplains of the regulated Green River to those of the unregulated Yampa River. We measured floodplain groundwater levels, soil water availability, cottonwood xylem pressure (Ψxp), and leaf-level stomatal conductance (gs) to assess current impacts of river regulation on the water status of adult cottonwoods. We also simulated a flood on the former floodplain of the regulated river to evaluate its impact on cottonwood water relations. Canopy and root structure were quantified with estimates of cottonwood leaf area and percent live canopy and root density and biomass, respectively. Regulation of the Green River has lowered the annual peak flow yet raised minimum flows in most years, resulting in a 60% smaller stage change, and lowered soil water availability by as much as 70% compared to predam conditions. Despite differences in water availability, daily and seasonal trends in Ψxp and gs were similar for cottonwoods on the regulated and unregulated rivers. In addition, soil water added with the experimental flood had little effect on cottonwood water relations, contrary to our expectations of alleviated water stress. Green River cottonwoods had 10%–30% lower stand leaf area, 40% lower root density, and 25% lower root biomass compared with those for Yampa River cottonwoods. Our results suggest that water relations at the leaf and stem level are currently similar for Yampa and Green River trees due to structural adjustments of cottonwood forests along the Green River, triggered by river regulation.

Chironomidae (diptera) responses to the experimental flooding of prairie marshes

This study examined chironomid responses to the flooding of ten drained experimental marshes in Delta Marsh, Manitoba, Canada. Emergence traps were used to monitor chironomid emergence from three vegetation types (Symphyotrichum ciliatum, Scolochloa festucacea, and Schoenoplectus tabernaemontani) flooded at two water depths (shallow: 20–40 cm, deep: 50–70 cm) over a four-year period. The greatest number (7,651 m−2 yr−1) and biomass (20.3 g m−2 yr−1) of chironomids emerged from Schoenoplectus-deep sites in the fourth year of flooding. Numbers, biomass, and size classes of emerging chironomids were similar over the four years from the Symphyotrichum habitat. However, chironomid emergence from Scolochloa and Schoenoplectus habitats was dominated initially by the smallest size class but shifted steadily toward production of much larger species over the four-year experiment. The production of chironomids as a potential food resource for waterfowl was high from the Symphyotrichum habitat during all four years of flooding, but emergence from the Scolochloa and Schoenoplectus habitats did not reach comparable levels until the third or fourth year.

Experimental Flooding of Grand Canyon Attempts to Restore Sandbars and Native Fish Habitat

Experimental Flooding of Grand Canyon Attempts to Restore Sandbars and Native Fish Habitat

BIOGEOCHEMICAL AND METABOLIC RESPONSES TO THE FLOOD PULSE IN A SEMIARID FLOODPLAIN

Flood pulse inundation of riparian forests alters rates of nutrient retention and organic matter processing in the aquatic ecosystems formed in the forest interior. Along the Middle Rio Grande (New Mexico, USA), impoundment and levee construction have created riparian forests that differ in their inter-flood intervals (IFIs) because some flood- plains are still regularly inundated by the flood pulse (i.e., connected), while other flood- plains remain isolated from flooding (i.e., disconnected). This research investigates how ecosystem responses to the flood pulse relate to forest IFI by quantifying nutrient and organic matter dynamics in the Rio Grande floodplain during three years of experimental flooding of the disconnected floodplain and during a single year of natural flooding of the connected floodplain. Surface and subsurface conditions in paired sites (control, flood) established in the two floodplain types were monitored to address metabolic and biogeochemical responses. Compared to dry controls, rates of respiration in the flooded sites increased by up to three orders of magnitude during the flood pulse. In the disconnected forest, month-long experimental floods produced widespread anoxia of four-week duration during each of the three years of flooding. In contrast, water in the connected floodplain remained well ox- ygenated (3-8 ppm). Material budgets for experimental floods showed the disconnected floodplain to be a sink for inorganic nitrogen and suspended solids, but a potential source of dissolved organic carbon (DOC). Compared to the main stem of the Rio Grande, flood- water on the connected floodplain contained less nitrate, but comparable concentrations of DOC, phosphate-phosphorus, and ammonium-nitrogen. Results suggest that floodplain IFI drives metabolic and biogeochemical responses dur- ing the flood pulse. Impoundment and fragmentation have altered floodplains from a mosaic of patches with variable IFI to a bimodal distribution. Relatively predictable flooding occurs in the connected forest, while inundation of the disconnected forest occurs only as the result of managed application of water. In semiarid floodplains, water is scarce except during the flood pulse. Ecosystem responses to the flood pulse are related to the IFI and other measures of flooding history that help describe spatial variation in ecosystem function.

Application of wavelet analysis for monitoring the hydrologic effects of dam operation: Glen Canyon Dam and the Colorado River at Lees Ferry, Arizona

Wavelet analysis is a powerful tool with which to analyse the hydrologic effects of dam construction and operation on river systems. Using continuous records of instantaneous discharge from the Lees Ferry gauging station and records of daily mean discharge from upstream tributaries, we conducted wavelet analyses of the hydrologic structure of the Colorado River in Grand Canyon. The wavelet power spectrum (WPS) of daily mean discharge provided a highly compressed and integrative picture of the post-dam elimination of pronounced annual and sub-annual flow features. The WPS of the continuous record showed the influence of diurnal and weekly power generation cycles, shifts in discharge management, and the 1996 experimental flood in the post-dam period. Normalization of the WPS by local wavelet spectra revealed the fine structure of modulation in discharge scale and amplitude and provides an extremely efficient tool with which to assess the relationships among hydrologic cycles and ecological and geomorphic systems. We extended our analysis to sections of the Snake River and showed how wavelet analysis can be used as a data mining technique. The wavelet approach is an especially promising tool with which to assess dam operation in less well-studied regions and to evaluate management attempts to reconstruct desired flow characteristics. Copyright © 2005 John Wiley & Sons, Ltd.

Factors influencing Gonyostomum semen blooms in a small boreal reservoir lake

Blooms of the nuisance alga Gonyostomum semen occurred in Lake 979 (Experimental Lakes Area), a small brown-water lake, that was subjected to several years of an experimental flooding regime. During periods of flooding, blooms of G. semen developed when light decreased below 100μmolm−2s−1 and total phosphorous concentrations increased to >30μgl−1. Gonyostomum semen biomass was significantly correlated with total P and DOC concentrations. In addition, G. semen abundance increased at times when Daphnia rosea had rapidly declined to<10 animals l−1. Daphnia egg ratios suggest that declines in Daphnia abundance were the result of shifts in mortality and not causally linked to changes in G. semen densities. The results observed in Lake 979 were supported by a laboratory experiment where the appearance of G. semen from Lake 979 sediment was stimulated by altering chemical and biological variables. The stimulation of G. semen blooms appears to be dependant on multiple variables rather than a single variable.

Immediate and habitat-specific responses of macroinvertebrates to sequential, experimental floods

Spatial and temporal patterns of transported organic matter (seston) and macroinverte- brates (drift) and benthic macroinvertebrate densities were examined before, during, and shortly after each of a series of scheduled, experimental floods in a flow-regulated river in the Swiss National Park. Temporal patterns in the lateral transfer of seston, drift, and benthic macroinvertebrates were evaluated in the flooded riparian area during 3 to 4 separate floods of different magnitude. No clear spatial pattern was found in the lateral transfer of seston, drift, or benthic macroinvertebrates, but the concentrations of seston and the densities of macroinvertebrates in the drift usually were lower in samples collected farthest from the main channel. Seston and drift increased significantly (from ,1 g to 4-20 g ash-free dry mass/m3 and ,10 to 250-1300 ind./m3, respectively) in the initial stages of each flood, but decreased to baseflow levels after ;2 to 3 h. Macroinvertebrates responded passively to the floods, and their densities followed the hysteresis pattern of sediment and organic particles entrained during the course of each flood. The total number of macroinvertebrates drifting during each flood ranged from 33 3 106 to .300 3 106 individuals. The average density of macroinvertebrates stranded in the riparian area after each flood ranged from ;6000 to 22,000 ind./m2. Benthic mac- roinvertebrates were collected from pool, run, bedrock, and riffle habitats in the main channel the day before and the morning after 5 floods to test whether specific habitats provided flow refugia for macroinvertebrates. Floods reduced macroinvertebrate densities by 14% to 92%, averaged across hab- itat types, and the % reduction was related to flood magnitude. Fewer organisms were lost from bedrock habitats (43%) than from the other habitat types, and the most macroinvertebrates typically were lost from pools (.90%). Macroinvertebrate responses (e.g., recovery patterns) changed signifi- cantly between early floods and sequentially later floods, reflecting temporal changes in assemblage composition and abundance.

Experimental Floods to Improve the Integrity of Regulated Rivers

Experimental Floods to Improve the Integrity of Regulated Rivers