Stream Restoration Research Articles

Beaver Pond Geomorphology Influences Pond Nitrogen Retention and Denitrification

AbstractBeaver ponds are increasingly promoted as a strategy for physical stream restoration, and more recently recognized as natural solutions for excess nonpoint source pollutants, such as nitrogen (N). Beaver ponds facilitate N transformations on the streamscape by increasing sediment‐water interactions and creating low and high redox conditions in close proximity. Because beaver ponds vary widely in their geomorphology, the spatial extent of morphological units should dictate the degree of biogeochemical processing. We explore the role of beaver pond geomorphic units in facilitating sediment N transformations using a sediment mass balance approach. We quantified input, output, and transformation of N species within the sediments and water of the riffle, backwater, and margin geomorphic units of a beaver pond in Northern Utah. Our interpretations were supplemented using sediment oxygen demand (SOD) and sediment C and N stable isotopes. The backwater performed most of the biogeochemical work, including increased sedimentation (2.1 g N m−2d−1), ammonification (1.3 g N m−2d−1), nitrification (0.07 g N m−2d−1), and denitrification (0.1 g N2 m−2 d−1), the latter facilitated by high sediment OM (14%) and SOD (−0.95 ± 0.2 g O2 m−2 d−1). Backwater sediment isotopes, supported by N flux measurements, indicated increased benthic microbial activity and denitrification. The margin and backwater surface sediments had low C:N ratios, indicating sediment input from autochthonous production. These findings suggest the representation of geomorphic units in a beaver pond may predict whether the pond can facilitate N removal through sediment sequestration and denitrification.

When is Aquatic Resource Type Conversion Appropriate: A Framework for Cleaning Sand out of the Gears and a Case Study for McInnis Marsh

Wetland and stream restoration projects may sometimes involve converting one “type” of aquatic habitat to another “type” (e.g., managed salt ponds into tidal marshes, depressional wetlands into streams, marsh into transition zone habitat). This “type conversion” may be necessary and beneficial in the context of addressing watershed plans or regional restoration goals, or in achieving resiliency to climatic changes (Goals Project 2015). Conversion can also occur through other large-scale, complex actions (e.g., mitigation banking initiatives). Whether driven by habitat restoration goals or compensatory mitigation needs or both, regulatory oversight typically governs the process. Holistically assessing such conversion through the regulatory lens is challenging for permitting programs. The challenge stems from how to accurately determine the overall value of an aquatic resource based on site-specific ecological properties and in the context of larger regional ecosystem management and goals. This is further compounded when assessing aquatic habitats that provide intrinsically different functions and services. Assessments must also account for the fact that wetlands and streams are not static ecosystems, but rather dynamically changing through time due to natural and anthropogenic factors, many of which are difficult to control or even accurately assess (e.g., sea level rise). These challenges are further exacerbated due to urbanization, conflicting human-environment goals, and the evolving state of habitat restoration science. Type conversion (i.e., replacing one aquatic type with a different aquatic habitat type) is recognized by agencies as a “sand in the gears” problem that can stymie planning and permitting because such actions typically require multiple agency authorizations (which may or may not be consistent with internal policies), habitat resource trade-offs, and consensus on ecosystem goals. The lack of consistent, defensible analysis based on transparent evaluation has been shown to impede critically needed habitat restoration (Bourgeois 2018; SFBRA 2022). To address this challenge, an interagency team of federal and state regulators and resource managers in California developed a structured and transparent approach for evaluating the appropriateness of aquatic resource type conversion. The resulting framework can support project planning and inform regulatory evaluation by helping to answer: 1) what loss or gain of function is expected from various aquatic resource type conversions, and 2) whether conversion might be ecologically (or functionally) appropriate. The framework is not intended to inherently value one type of aquatic resource over another, nor to supersede regulatory mandates. Rather, the intent is to support agencies’ technical and regulatory decisions by providing a standardized, transparent set of tools and approaches that can inform discussions between agencies and with project proponents during the project evaluation phase, with a goal of ensuring that projects are not only permittable, but environmentally beneficial. The framework consists of three modules that can be done either sequentially or in parallel. Together they can be used to assess the feasibility/suitability, functions, and regional context of a proposed type conversion project (Figure 1).

The Impact of Water Body Restoration on the Sales and Rental Markets in Beijing

<h3>Abstract</h3> Black and odorous water bodies (BOWBs) are increasingly common in cities worldwide. This paper evaluates the impact of an urban water bodies restoration program in Beijing, China, based on detailed housing sale and rental transaction data. We implement a hedonic price model with a difference-in-difference and a triple difference approach and find that listing and restoration of a BOWB significantly increase house prices by 2.2-3.9 percent and 2.3-4.9 percent, respectively, while at the same time increase rents by 11.3-13.7 percent and 13.4-16.9 percent, respectively.

Application of floating wetlands for the improvement of degraded urban waters: Findings from three multi-year pilot-scale installations

Floating Treatment Wetlands (FTWs) are an emerging ecological engineering technology being applied the restoration of eutrophic urban water bodies. Documented water-quality benefits of FTW include nutrient removal, transformation of pollutants, and reduction in bacterial contamination. However, translating findings from short-duration lab and mesocosm scale experiments, into sizing criteria that might be applied to field installations is not straightforward. This study presents the results of three well established (>3 years) pilot-scale (40–280 m2) FTW installations in Baltimore, Boston, and Chicago. We quantify annual phosphorus removal through harvesting of above-ground vegetation and find an average removal rate of 2 g-P m−2. In our own study and in a review of literature, we find limited evidence of enhanced sedimentation as a pathway for phosphorus removal. In addition to water-quality benefits, FTW planted with native species, provide valuable wetland habitat; and theoretically improve ecological function. We document efforts to quantify the local effect of FTW installations on benthic and sessile macroinvertebrates, zooplankton, bloom-forming cyanobacteria, and fish. Data from these three projects suggest that, even on a small scale, FTW produce localized changes in biotic structure that reflect improving environmental quality. This study provides a simple and defensible method for sizing FTW for nutrient removal in eutrophic waterbodies. We propose several key research pathways which would advance our understanding of the effects FTW have on the ecosystem they are deployed in.

Combined Surface-Subsurface Stream Restoration Structures Can Optimize Hyporheic Attenuation of Stream Water Contaminants.

There is a design-to-function knowledge gap regarding how engineered stream restoration structures can maximize hyporheic contaminant attenuation. Surface and subsurface structures have each been studied in isolation as techniques to restore hyporheic exchange, but surface-subsurface structures have not been investigated or optimized in an integrated manner. Here, we used a numerical model to systematically evaluate key design variables for combined surface (i.e., weir height and length) and subsurface (i.e., upstream and downstream baffle plate spacing) structures. We also compared performance metrics that place differing emphasis on hyporheic flux versus transit times. We found that surface structures tended to create higher flux, shorter transit time flowpaths, whereas subsurface structures promoted moderate-flux, longer transit time flowpaths. Optimal combined surface-subsurface structures could increase fluxes and transit times simultaneously, thus providing conditions for contaminant attenuation that were many times more effective than surface or subsurface structures alone. All performance metrics were improved by the presence of an upstream plate and the absence of a downstream plate. Increasing the weir length tended to improve all metrics, whereas the optimal weir height varied based on metrics. These findings may improve stream restoration by better aligning specific restoration goals with appropriate performance metrics and hyporheic structure designs.

Possibilities of Improving Water Quality of Degraded Lake Affected by Nutrient Overloading from Agricultural Sources by the Multi-Point Aeration Technique

This research concerns the restoration of the strongly eutrophied Lake Łajskie (Masurian Lake District, Poland) that received pollutants from the agricultural catchment. It is a shallow (max depth 7.4 m) and small (area 48 ha) reservoir with a wide profundal zone characterized by complete deoxidation in summer. Due to its important natural and social role, the lake has undergone a restoration process. Artificial oxygenation is the main method of improving water quality. Due to unfavorable morphometric conditions, the necessity to use multi-point aeration was assumed. An experimental installation based on eight reactors selectively oxygenating only the over-bottom waters was launched in 2019. In 2021, spatial studies of the effectiveness of aerators’ work were carried out at 96 measuring points grouped into 12-test fields around each reactor. The investigations were performed three times during the summer season. It was shown that, in the water of the deepest layers of Lake Łajskie, the oxygen concentration around all reactors increased to an average level of 1–2 mg L−1. The oxygenation efficiency was varied and related to the distance from the aerator and the location in relation to the direction of oxygenated water outflow. The results of the research indicate the legitimacy of designing multi-point oxygenation systems in the restoration of waterbodies degraded as a result of the impact of agriculturally transformed catchments.

Integrating channel design and assessment methods based on sediment transport capacity in gravel bed streams

AbstractNatural channel design (NCD) and analytical channel design (ACD) are two competing approaches to stable channel design that share fundamental similarities in accounting for sediment transport processes with designs based on hybrid fluvial geomorphology and hydraulic engineering methods. In this paper, we highlight the linkage between ACD's capacity/supply ratio (CSR) and NCD's sediment capacity models (FLOWSED/POWERSED), illustrating how ACD and NCD have reached a point of convergent evolution within the stream restoration toolbox. We modified an existing CSR analytical spreadsheet tool which enabled us to predict relative channel stability using both conventional bed load transport equations and regional sediment regression curves. The stable channel design solutions based on measured data most closely matched the Parker (ACD) and/or Pagosa good/fair (NCD) relationships, which also showed the greatest CSR sensitivity in response to channel alterations. We found that CSR differences among the transport relationships became more extreme the further the design width deviated from the supply reach, suggesting that a stable upstream supply reach may serve as the best design analog. With this paper, we take a step toward resolving lingering controversy in the field of stream restoration, advancing the science and practice by reconciling key differences between ACD and NCD in the context of reach scale morphodynamics.

Use of UAV Monitoring to Identify Factors Limiting the Sustainability of Stream Restoration Projects

The detection and mapping of riverscapes with Unmanned Aerial Vehicles (UAVs, drones) provide detailed, reliable, and operable spatial information in hydrological sciences, enhancing conventional field survey techniques. In this study, we present the results of long-term, optical RGB (red, green, blue) UAV monitoring of stream restoration projects to identify the positive and negative features that affect their sustainability. We determined quantitative and qualitative aspects of restoration, such as the restoration effect, the dynamics of fluvial processes, hydrological connectivity, and riparian vegetation. The study was based on six years of UAV monitoring in three restored streams in Prague, Czech Republic. The multitemporal riverscape models from the photogrammetric reconstruction served as a basis for the visual assessment, compliant with the standard hydromorphological assessment. Such a combined approach extends the potential of UAV monitoring by allowing for the use of existing classification schemes and data and the objective detection of critical features. The study pointed to the significant discrepancies in channel geometry between the planned restorations and realized restorations in all assessed projects as a general phenomenon. Multitemporal, optical RGB UAV monitoring then detected issues in qualitative aspects that limit restoration quality, such as water overuse, extensive eutrophication, or inefficient riparian shading.

Changes in hydrology and pollutant loads from stream restoration in an urban headwater catchment

Stream restoration structures can alter the hydrology and biogeochemical processes of urban headwater streams in important ways. As a stream restoration design, regenerative stormwater conveyance (RSC) structures are built to reconnect floodplains to stream channels, raise the groundwater table, and increase streamwater retention times. Altered hydrology and flow dynamics within restored stream reaches can affect solute concentrations and loads in baseflow and stormflow runoff. We monitored interannual changes in precipitation, groundwater and stream runoff before and after the implementation of a stream restoration using an RSC design in order to evaluate changes in hydrology and to estimate changes in solute loads of an urban headwater catchment in the Rock Creek watershed of Washington DC. A Before After Control Impact (BACI) experimental design was used. Compared to the control catchment, average recharge of the groundwater system of the RSC riparian area increased by 0.76 m in the post-restoration period and contributed to a 6 % increase in baseflow as a percentage of total runoff (compared to a decrease of 6 % in the control catchment). Area yields from the pre- to the post-restoration monitoring period decreased in both the RSC and control catchments, but significantly larger decreases in total nitrogen (TN), total phosphorus (TP) and total suspended solids (TSS) occurred in the RSC catchment (i.e., −59 % vs −23 %, −54 % vs −28 %, and −76 % vs −40 %, respectively). Results of this study indicate that RSCs as stream restoration structures in degraded headwater catchments can result in important hydrological and biogeochemical changes that significantly reduce nutrient and sediment loads.

The Roles of Microbes in Stream Restorations.

The goods and services provided by riverine systems are critical to humanity, and our reliance increases with our growing population and demands. As our activities expand, these systems continue to degrade throughout the world even as we try to restore them, and many efforts have not met expectations. One way to increase restoration effectiveness could be to explicitly design restorations to promote microbial communities, which are responsible for much of the organic matter breakdown, nutrient removal or transformation, pollutant removal, and biomass production in river ecosystems. In this paper, we discuss several design concepts that purposefully create conditions for these various microbial goods and services, and allow microbes to act as ecological restoration engineers. Focusing on microbial diversity and function could improve restoration effectiveness and overall ecosystem resilience to the stressors that caused the need for the restoration. Advances in next-generation sequencing now allow the use of microbial 'omics techniques (e.g., metagenomics, metatranscriptomics) to assess stream ecological conditions in similar fashion to fish and benthic macroinvertebrates. Using representative microbial communities from stream sediments, biofilms, and the water column may greatly advance assessment capabilities. Microbes can assess restorations and ecosystem function where animals may not currently be present, and thus may serve as diagnostics for the suitability of animal reintroductions. Emerging applications such as ecological metatranscriptomics may further advance our understanding of the roles of specific restoration designs towards ecological services as well as assess restoration effectiveness.

The Role of the Microbiome in the Etiology of Inflammatory Bowel Diseases.

Inflammatory bowel diseases (IBDs) result from dysregulated immune responses to environmental and microbial triggers in genetically susceptible hosts. Many clinical observations and animal studies support the role of the microbiome in the pathogenesis of IBD. Restoration of the fecal stream leads to postoperative Crohn's recurrence, while diversion can treat active inflammation. Antibiotics can be effective in prevention of postoperative Crohn's recurrence and in pouch inflammation. Several gene mutations associated with Crohn's risk lead to functional changes in microbial sensing and handling. However, the evidence linking the microbiome to the IBD is largely correlative, given the difficulty in studying the microbiome before disease occurs. Attempts to modify the microbial triggers of inflammation have had modest success to date. Exclusive enteral nutrition can treat Crohn's inflammation though no whole food diet to date has been shown to treat inflammation. Manipulation of the microbiome through fecal microbiota transplant and probiotics have had limited success. Further focus on early changes in the microbiome and functional consequences of microbial changes through the study of metabolomics are needed to help advance the field.

A multiscale landscape approach for prioritizing river and stream protection and restoration actions.

River and stream conservation programs have historically focused on a single spatial scale, for example, a watershed or stream site. Recently, the use of landscape information (e.g., land use and land cover) at multiple spatial scales and over large spatial extents has highlighted the importance of incorporating a landscape perspective into stream protection and restoration activities. Previously, we developed a novel framework that links information about watershed-, catchment-, and reach-scale integrity with stream biological condition using scatterplots and a landscape integrity map. Here we examined an application of this approach for streams in urban and other settings in King County, Washington State, United States, where we related stream macroinvertebrate condition to two indices of landscape integrity, the US Environmental Protection Agency's (USEPA) nationally available Index of Watershed Integrity (IWI) and Index of Catchment Integrity (ICI). We generated a scatterplot of IWI versus ICI for sample sites, where points represented site macroinvertebrate condition from poor to good. The same data were also visualized as a landscape integrity map that displayed catchments of King County according to the level of watershed and catchment integrity (high or low IWI/ICI). Almost three-quarters of poor-condition sites were associated with high-integrity watersheds and catchments (i.e., underperforming sites), which suggested that either one or both national indicators were insufficient for this area, and that sites underperformed because of local-scale factors. In response, we used a catchment-scale indicator related to forest condition (PctForestCat) after examining several GIS-based dispersal indicators from the National Hydrography Dataset and other candidates from the USEPA's StreamCat dataset. We then compared the results of the scatterplots and maps based on the current and original analyses and found that many of the sites previously classified as underperforming now performed as expected, that is, they were poor-condition sites in poor-condition catchments. This analysis demonstrates how results based on a national dataset can be improved by developing an alternative that represents regionally important stressors. The methods used to develop an effective landscape indicator based on StreamCat datasets, and the utility of the multiscale approach, could provide important tools for prioritizing, optimizing, and communicating stream conservation actions.

Cost-Benefit Analysis of Urban Stream Restoration

The District of Columbia Department of Energy and Environment (DC DOEE) and National Park Service (NPS) have worked in tandem on multiple stream restorations throughout the Washington DC area. Restored stream ecosystems provide a variety of direct and indirect environmental benefits, such as improved stormwater management, water quality, and recreational value.

Streambank Erosion Phenomena and Understanding: Current Research and Future Directions

Highlights High rates of streambank erosion are detrimental to the stability and function of streams. This collection brings together six studies that represent key advances in streambank erosion research. Current research directions on streambank erosion, erodibility characterization, and sediment loading are presented. Future research directions and challenges related to high-frequency data collection and modeling are discussed. Abstract. Streams are in dynamic equilibrium with their environments, and as that environment is altered by human development and changing climate, streambank erosion is a common, but little understood, result. This article highlights the contributions of the special collection “Streambank Erosion, Sediment Dynamics, and Restoration (SER),” which assembled six studies that represent key advances in streambank erosion research, highlight current research in the field, and identify directions for future research. The studies in this special collection were grouped into three central themes: (1) streambank erosion monitoring, (2) streambank erodibility characterization, and (3) streambank erosion loading. In this article, key findings within each of these central themes are summarized, emphasizing the significant contributions of each study. Likewise, perspectives on future research directions are discussed, outlining important challenges that remain to be addressed. Overall, the studies in this special collection are unified in their overarching goal of improving quantitative and predictive understanding of streambank erosion phenomena. Keywords: Keywords., Erodibility Parameters, Jet Erosion Test, Monitoring, Sediment, Soil Erosion, Stabilization Practices, Streambank, Stream Restoration.

Restored tufa-depositing streams: a dynamic interface between terrestrial and aquatic ecosystems

Stream periphyton has implications for ecosystem processes, yet little is known about its function in response to restoration efforts. In this study, we compared the taxonomic and functional composition of periphytic ciliates between restored and unrestored (control) streams for two different immersion periods to identify species with indicator potential, identify ciliate functional traits that differ between the two stream types, and examine the effects of environmental parameters on species and functional trait composition. Our study showed that restored streams differed from control streams in terms of species and functional trait composition. In restored streams, better competitors, i.e., omnivorous and bacterivorous free-swimming ciliates predominated, utilizing a wider range of different niches created by the greater microhabitat complexity due to retention of allochthonous organic matter particles and precipitation of calcite crystals, i.e., tufa. One of these species was Platyophrya vorax, which was identified as a species with indicator potential for restored tufa-depositing streams. The relationship between habitat heterogeneity, ciliate functional traits, and organic matter dynamics suggests that restoration of tufa-depositing streams affects ecosystem functioning by influencing its functional components, highlighting the need to investigate such ecosystems through the prism of connected lotic and terrestrial ecosystems rather than isolated ecosystems.

Examining meandering stream by using geomorphological characteristics with GIS-based analysis

An assessment of the meandering stream type using its classification system to geomorphology characteristics combined with GIS-based analysis is presented in this paper. It describes geomorphology characteristics consisting of 8 parameters with GIS-based analysis that differ in the zone of sediment position, stream width, stream sinuosity, amplitude, wavelength, bend sharpness, meander pattern, and slope. The selected case study in this paper is the Barito Stream, South Kalimantan, Indonesia. Based on the results, the variability varied in all the geomorphology characteristics except bend sharpness and slope. The transport zone is the longest zone with classified as a very wide river with moderate sinuosity and high amplitude (&lt; 1500). It is also categorized as a moderate wavelength and sharp bend with a relatively shallow slope. This approach is a simple, appropriate, and easy-to-use practice in examining meandering stream since there is no data or lack of supporting field data. The implementation of this meandering stream classification method is suitable for stream restoration projects, fish habitat enhancement, and water resource management. Further research is the study of possible geomorphic responses of a channel to natural and anthropogenic disturbances including channel-bed degradation, channel-bed aggradation, channel widening, and channel straightening.

Significance of small stream restoration and river network on freshwater fish diversity.

Significance of small stream restoration and river network on freshwater fish diversity.

When is Aquatic Resource Type Conversion Appropriate: A Framework for Cleaning Sand out of the Gears and a Case Study for McInnis Marsh

Wetland and stream restoration projects may sometimes involve converting one “type” of aquatic habitat to another “type” (e.g., managed salt ponds into tidal marshes, depressional wetlands into streams, marsh into transition zone habitat). This “type conversion” may be necessary and beneficial in the context of addressing watershed plans or regional restoration goals, or in achieving resiliency to climatic changes (Goals Project 2015). Conversion can also occur through other large-scale, complex actions (e.g., mitigation banking initiatives). Whether driven by habitat restoration goals or compensatory mitigation needs or both, regulatory oversight typically governs the process. Holistically assessing such conversion through the regulatory lens is challenging for permitting programs. To address this challenge, an interagency team of federal and state regulators and resource managers in California developed a structured and transparent approach for evaluating the appropriateness of aquatic resource type conversion. The resulting framework can support project planning and inform regulatory evaluation by helping to answer: 1) what loss or gain of function is expected from various aquatic resource type conversions, and 2) whether conversion might be ecologically (or functionally) appropriate. The intent is to support agencies’ technical and regulatory decisions by providing a standardized, transparent set of tools and approaches that can inform discussions between agencies and with project proponents during the project evaluation phase, with a goal of ensuring that projects are not only permittable, but environmentally beneficial.

The Use of Green Laser in LiDAR Bathymetry: State of the Art and Recent Advancements

Bathymetric LiDAR technology is a technology used for simultaneous data acquisition regarding the morphology of the bottom of water reservoirs and the surrounding coastal zone, realized from the air, e.g., by plane or drone. Contrary to the air topographic LiDAR, which uses an infrared wavelength of 1064 nm, bathymetric LiDAR systems additionally use a green wavelength of 532 nm. The green laser can penetrate the water, which makes it possible to measure the depth of shallow water reservoirs, rivers, and coastal sea waters within three Secchi depths. This article presents the theoretical basis for the construction of a green laser. Against the background of other methods of measuring the bottom of water reservoirs, the technology using waves from the visible light range is presented in detail in the assessment of the bottom morphology of shallow water reservoirs. The possibilities of using green laser in lidar bathymetry implemented in particular in non-navigable regions are shown. The results of the researchers' work on river processes (erosion, sedimentation), design of stream restoration, determination of morphometric parameters of the riverbed, as well as assessment of the topography of the marine coastal bottom zones are summarized. The development direction of lidar bathymetry is discussed.

Aquatic invertebrate responses to riparian restoration and flow extremes in three degraded intermittent streams: An eight‐year field experiment

Abstract Worldwide, riparian zones of many intermittent rivers and ephemeral streams (IRES) have been severely degraded. However, compared with perennially flowing waters, there have been few restoration efforts (e.g., revegetation, livestock removal) to halt or reverse this degradation. Even rarer are assessments of whether desired responses occurred and, if so, their underlying mechanisms, especially where flow extremes such as drying and flooding in IRES might alter or delay ecological responses to restoration. In order to assess how aquatic invertebrate communities responded to riparian replanting and livestock removal in three degraded lowland IRES in southeastern Australia, we conducted an eight‐year experiment (2004–2013), sampling paired control (unrestored) and treatment (restored, between 2005 and 2007 across creeks) sites twice yearly before and after restoration. To evaluate likely mechanisms underlying invertebrate responses to riparian restoration, we used a range of structural (e.g., richness) and functional (e.g., trait‐based) metrics. We also monitored environmental variables predicted to be likely drivers of aquatic invertebrate responses such as macrophyte and canopy cover, water quality, instream organic matter and instream wood. The study coincided with the last few years of a decade‐long drought that broke with severe floods (in 2010–2012), so we opportunistically examined how these hydrological extremes affected invertebrate responses to riparian restoration. At all three sites, macrophyte and canopy cover, water quality, organic matter and instream wood were comparable at treatment and control sites throughout the eight‐year experiment. There were also no significant differences in structural or functional metrics to indicate aquatic invertebrate responses to restoration after 6–8 years. This lack of predicted invertebrate responses apparently reflected how severely the drought impeded the riparian restoration, delaying even short‐term responses. Pervasive effects of catchment‐scale degradation may have further diminished the predicted benefits of the reach‐scale restoration efforts. By contrast, invertebrate metrics responded strongly to flow extremes, especially the brief floods that occurred as drought broke. These responses were evident for functional groups and individual families (especially rheophilic ones), but were not detected by a commonly used integrative measure of stream condition. This highlights the importance of selecting appropriate indicators in restoration monitoring programs and recognising their variability in responsiveness to restoration versus flow extremes. IRES are abundant and, in many parts of the world, increasingly common. Understanding how their inherent hydrological extremes may delay, modify and even overwhelm predicted responses to riparian restoration is crucial to setting realistic goals for IRES in the Anthropocene. Furthermore, assessing the success of riparian restoration in IRES requires a long‐term view given the extended time frames over which responses may occur, especially when expectations are often based on results of riparian restoration of perennial streams and rivers.