River Restoration Research Articles

Ecological Restoration and Renovation of Xin River Based on Sponge City Concept

China is currently facing various water problems such as water scarcity, water pollution, floods, and loss of aquatic habitats. These water problem syndromes are systemic and comprehensive problems that urgently require a more comprehensive solution. The proposal of the "Sponge City" theory is based on this background. According to Jiaozuo "7.20 extremely heavy rainstorm Event", based on the sponge city theory, citing ecological principles, and following ecological principles, this paper discusses the ecological transformation of the Xin River to achieve the purpose of artificially rebuilding the river ecosystem.

Collaborative Planning in the Context of Deindustrialization: A Qualitative Evaluation of Comparative Cases in Northeast Ohio

This article investigates whether and how the contexts of the Rust Belt decline extend collaborative planning theory. We evaluate two collaborative planning projects in Northeast Ohio: (1) the Cuyahoga Greenways (CG), a regional trails project and (2) the Mahoning River Corridor Initiative (MRCI), a postindustrial river restoration project. Based on participant interviews and document analysis, we find that the projects are distinct in their contextual conditions and collaborative processes, with CG better aligning with common expectations found in the literature. MRCI deviates from normative theory pertaining to collaborative planning; we discuss how this might relate to processes of institutional change. Our results suggest that the collaborative planning literature is insufficiently tailored to assess collaborative projects in the context of decline—particularly where there is controversy around the project and where collaborative institutions and networks are weak.

Pro+: Automated protrusion and critical shear stress estimates from 3D point clouds of gravel beds

AbstractThe dimensionless critical shear stress (τ*c) needed for the onset of sediment motion is important for a range of studies from river restoration projects to landscape evolution calculations. Many studies simply assume a τ*c value within the large range of scatter observed in gravel‐bedded rivers because direct field estimates are difficult to obtain. Informed choices of reach‐scale τ*c values could instead be obtained from force balance calculations that include particle‐scale bed structure and flow conditions. Particle‐scale bed structure is also difficult to measure, precluding wide adoption of such force‐balance τ*c values. Recent studies have demonstrated that bed grain size distributions (GSD) can be determined from detailed point clouds (e.g. using G3Point open‐source software). We build on these point cloud methods to introduce Pro+, software that estimates particle‐scale protrusion distributions and τ*c for each grain size and for the entire bed using a force‐balance model. We validated G3Point and Pro+ using two laboratory flume experiments with different grain size distributions and bed topographies. Commonly used definitions of protrusion may not produce representative τ*c distributions, and Pro+ includes new protrusion definitions to better include flow and bed structure influences on particle mobility. The combined G3Point/Pro+ provided accurate grain size, protrusion and τ*c distributions with simple GSD calibration. The largest source of error in protrusion and τ*c distributions were from incorrect grain boundaries and grain locations in G3Point, and calibration of grain software beyond comparing GSD is likely needed. Pro+ can be coupled with grain identifying software and relatively easily obtainable data to provide informed estimates of τ*c. These could replace arbitrary choices of τ*c and potentially improve channel stability and sediment transport estimates.

River restoration as a sociocultural process: A case study from the Waimatā Catchment, Aotearoa New Zealand

River restoration as a sociocultural process: A case study from the Waimatā Catchment, Aotearoa New Zealand

The effect of bed load sediments on self-purification of river – Experimental approach

Assessing the profitability of river restoration requires knowledge of the importance of individual ecosystem elements for the value of specific ecosystem services. The aim of this study was to experimentally estimate the effect of the presence of bed load on the processes of water self-purification from suspended solids, organic matter and microplastic fibres. The experiment was carried out in channels with and without bed load, simulating conditions in a lowland river. The system was supplemented with artificial sewage containing FPOM and polypropylene fibres. Changes in the amount of suspended solids in the water, as well as organic matter and microplastics in the water and sediment, were recorded over the course of a week. The presence of a bed load increased the rate of suspension removal from the river water many times over. The decomposition rate of organic matter in the sediment was much higher than in the water, reaching 1 g of organic carbon per week. Bed load favoured the immobilisation of large microplastic fibres, facilitating their incorporation into bottom biofilms. The fibres formed a 'skeleton' that led to the formation of larger bed load biofilms. The study suggests that, even without restoring the connection between river water and groundwater, the supply of bed load to the river significantly increases the efficiency of natural processes in the river ecosystem, including self-purification.

Experimental investigation of three-dimensional flow dynamics in a laboratory-scale meandering channel under subcritical flow condition

This study investigates the three-dimensional turbulence flow properties in a meandering channel under subcritical flow conditions, specifically focusing on a few critical parameters such as three-dimensional velocity behaviour, Turbulent kinetic energy, skewness, and kurtosis. A model study has been attempted by considering the same sinuosity, Froude number, and bed material from an Indian peninsular river to understand the basic hydrodynamics of a meandering channel. Understanding these critical parameters is crucial for comprehending the complex flow behaviour and its implications in meandering channels. Experimental measurements were conducted to collect data on Velocity, Turbulent Kinetic energy, skewness, and kurtosis in all three directions. The objective was to analyse their variations and behaviour along the meandering path, providing insights into the flow dynamics and turbulence characteristics. Advanced measurement techniques, such as Acoustic Doppler Velocimeters (ADV), were utilized to obtain accurate and detailed data. The study revealed distinct patterns and trends in the velocity, Turbulent Kinetic energy, skewness, and kurtosis along the flow path of a sand bed meandering channel. These parameters were found to vary significantly in different sections, highlighting the influence of channel geometry and flow conditions. Graphical representations of the flow profiles were employed to visualize the spatial distribution and understand the variations in these turbulence properties. The findings of this study enhance our understanding of the three-dimensional turbulence flow properties in sand bed meandering channels under subcritical flow conditions. The results offer valuable information for designing hydraulic structures, flood control measures, and river restoration projects.

Sinuosity‐Driven Hyporheic Exchange: Hydrodynamics and Biogeochemical Potentials

AbstractHydrologic exchange processes are critical for ecosystem services along river corridors. Meandering contributes to this exchange by driving channel water, solutes, and energy through the surrounding alluvium, a process called sinuosity‐driven hyporheic exchange. This exchange is embedded within and modulated by the regional groundwater flow (RGF), which compresses the hyporheic zone and potentially diminishes its overall impact. Quantifying the role of sinuosity‐driven hyporheic exchange at the reach‐to‐watershed scale requires a mechanistic understanding of the interplay between drivers (meander planform) and modulators (RGF) and its implications for biogeochemical transformations. Here, we use a 2D, vertically integrated numerical model for flow, transport, and reaction to analyze sinuosity‐driven hyporheic exchange systematically. Using this model, we propose a dimensionless framework to explore the role of meander planform and RGF in hydrodynamics and how they constrain nitrogen cycling. Our results highlight the importance of meander topology for water flow and age. We demonstrate how the meander neck induces a shielding effect that protects the hyporheic zone against RGF, imposing a physical constraint on biogeochemical transformations. Furthermore, we explore the conditions when a meander acts as a net nitrogen source or sink. This transition in the net biogeochemical potential is described by a handful of dimensionless physical and biogeochemical parameters that can be measured or constrained from literature and remote sensing. This work provides a new physically based model that quantifies sinuosity‐driven hyporheic exchange and biogeochemical reactions, a critical step toward their representation in water quality models and the design and assessment of river restoration strategies.

Flow resistance law in channels with emergent rigid vegetation

AbstractFlow resistance estimate is a challenging topic for establishing flooding propensity of streams, designing river restoration works, and evaluating the use of soil bioengineering practices. In this paper, flume measurements with rigid cylinders set in two arrangements (aligned, staggered) were used to evaluate the effect of rigid emergent vegetation on flow resistance. A well‐known theoretical flow resistance equation was firstly reviewed. Then, it was calibrated and tested by measurements performed for these arrangements with six concentrations (0.53–11.62 stems dm−2). The analysis was conducted using three approaches: (i) distinguishing the experimental runs corresponding to different arrangements and stem concentrations; (ii) using only a scale factor representing the effect of the stem concentration; and (iii) joining all available data. The results demonstrated that the flow resistance equation gives an accurate estimate of the Darcy–Weisbach friction factor f, characterized, for the best approach among the tested ones, by errors less than or equal to ±5% for 95.9% of the examined cases for the aligned arrangement and for the staggered arrangement less than or equal to ±5% for 94.2% of the examined cases. For both arrangements, the measurements demonstrated that, for a given longitudinal distance between vegetation elements, flow resistance increases for decreasing values of the transverse distance and, for a given transverse distance, f decreases for increasing values of the longitudinal distance between elements. Finally, in the range of the investigated stem concentrations, the influence of the arrangement on flow resistance resulted negligible.

Urban river recovery: a systematic review on the effectiveness of water clean-up programs.

Urban rivers are affected at different levels by the intensification of human activities, representing a serious threat to the maintenance of terrestrial life and sustainable urban development. Consequently, great efforts have been dedicated to the ecological restoration of urban rivers around the world, as a solution to recovering the environmental functionality of these environments. In this sense, the present work aimed to investigate the effectiveness of interventions carried out aimed at the recovery of urban rivers, through a systematic review of the literature between 2010 and 2022, using the search term "rivers recovery." The results showed that there have been notable advances in the implementation of river recovery programs in urban areas around the world between the years analyzed. The ecosystems studied were affected, for the most part, by the increase in the supply of nutrients from domestic and industrial effluents, in addition to having highly urbanized surroundings and with several changes in land use patterns. The preparation of this literature review made it possible to demonstrate that the effectiveness of river recovery is extremely complex, since river recovery projects are developed for different reasons, as well as being carried out in different ways according to the intended objective.

Biogeomorphological response to river restoration of a suburban river with large wood: Creating a restoration vision and cost‐effectively monitoring the response trajectory using the citizen science MoRPh survey

AbstractBiogeomorphological responses to river restoration are rarely reported. Despite a transition in the emphasis and priorities of river management over the last 40 years from controlling river channel forms and processes to restoring and supporting natural processes, forms and functions, remarkably little information is available on project outcomes. Here, using the example of Beverley Brook within Wimbledon Common, Greater London, UK, we illustrate how standardised detailed monitoring information can be assembled at a very low cost using the citizen science MoRPh survey and we demonstrate the importance of having a pre‐project vision of likely outcomes that can be tracked by the monitoring programme. We show how a pre‐project and five post‐project surveys undertaken over 4 years according to a before‐after‐control‐impact (BACI) design provides scientifically robust data. Analysis of the survey data quantifies the nature, abundance and spatial distribution of restoration interventions, the immediate responses to those interventions, and the ensuing trajectory of biogeomorphological adjustments. Changes in the persistence, size, position, abundance and evolution of habitats reveal the degree to which the restoration achieved the pre‐project biogeomorphological vision and why the recovery trajectory progressed at the observed rate and to the observed end point over 4 years. Our approach has enormous potential for monitoring the outcomes of river interventions. Whilst our project was limited in its spatial scale and focus on physical habitats, we suggest how these limitations could be overcome whilst still containing costs.

Assessing environmental awareness activism to river decay and recurring pollution using parallel multiple mediator model

ABSTRACT The decay of rivers coupled with its escalated pollution is a concern worldwide. The present study intends to assess the agony of the riverine people due to the contamination of the Churni River and the transformation of their grievance into environmental activism at individual and community levels for rejuvenating the river and for a secured livelihood. The study observed an enriched concentration of biological oxygen demand, nitrate, and phosphate and a reduced concentration of dissolved oxygen during 2011–2020 due to the release of untreated industrial wastewater, sewage from urban areas, and agricultural runoff into the river. A systematic investigation reveals pollution-induced socio-psychological trauma and community awareness leading to the active involvement of the people in the environmental awareness movement, which was mediated by self-efficacy, self-responsibility, self-identity, and community value. A parallel multiple mediator model was employed, which included 29 parameters for exploring the key-mediated factors for the environmental movement. The model-based results identified that self-responsibility and community-value for upper stretch villages and self-efficacy and community-value for the lower stretch villages are significant mediators of environmental activism. A canonical component analysis predicted socio-demographic factors (e.g. age, dependency ratio female-male ratio, etc.) as intrinsically linked to environmental activism. This study is significant because it reveals how pollution and river degradation affect riverine people. It also clarifies how local grievances turned into environmental activism as a result of the documented socio-psychological trauma and growing community awareness. This study would thus play a pivotal role in understanding the human-nature complex to better planning and river restoration.

Microeukaryotic plankton community dynamics under ecological water replenishment: Insights from eDNA metabarcoding

Ecological water replenishment (EWR) is an important strategy for river restoration globally, but timely evaluation of its ecological effects at a large spatiotemporal scale to further adjust the EWR schemes is of great challenge. Here, we examine the impact of EWR on microeukaryotic plankton communities in three distinct river ecosystems through environmental DNA (eDNA) metabarcoding. The three ecosystems include a long-term cut-off river, a short-term connected river after EWR, and long-term connected rivers. We analyzed community stability by investigating species composition, stochastic and deterministic dynamics interplay, and ecological network robustness. We found that EWR markedly reduced the diversity and complexity of microeukaryotic plankton, altered their community dynamics, and lessened the variation within the community. Moreover, EWR disrupted the deterministic patterns of community organization, favoring dispersal constraints, and aligning with trends observed in naturally connected rivers. The shift from an isolated to a temporarily connected river appeared to transition community structuring mechanisms from deterministic to stochastic dominance, whereas, in permanently connected rivers, both forces concurrently influenced community assembly. The ecological network in temporarily connected rivers post-EWR demonstrated significantly greater stability and intricacy compared to other river systems. This shift markedly bolstered the resilience of the ecological network. The eDNA metabarcoding insights offer a novel understanding of ecosystem resilience under EWR interventions, which could be critical in assessing the effects of river restoration projects throughout their life cycle.

Width undulation drives flow convergence routing in five flashy ephemeral river types across a dry summer subtropical region

AbstractDuring the last decade, meter‐resolution topo‐bathymetric digital elevation models (DEMs) have become increasingly utilized within fluvial geomorphology, but most meter‐scale geomorphic analyses are done on just one to a few rivers. While such analyses have contributed greatly to our collective understanding of river discharge‐topography interactions, which is applicable in both river restoration design and environmental flow regulation contexts, their generalizability across a range of river types remains largely unevaluated. This study assessed the dominance of a single hydro‐morphodynamic mechanism, flow convergence routing, in 35 ephemeral rivers divided among five river types in California's South Coast region by answering five questions. Geomorphic covariance structure (GCS) analysis was performed on longitudinal standardized width and standardized, detrended bed elevation spatial series from meter‐resolution DEMs. All river types had coherent, multi‐scalar structures of longitudinal fluvial topography, implicating a process‐morphology link. GCS metrics revealed that landform patterning was consistent with the requirements of the morphodynamic mechanism of flow convergence routing. Thus, that process was found to be a broadly relevant channel altering mechanism among sites, but its relationship with water stage differed between river types. Specifically, river types in unconfined valleys exhibited a strong bankfull width control over base flow bed undulations, with no obvious flood‐stage control over bankfull landform patterning. River types in partially confined valleys also exhibited strong bankfull width control over base flow bed undulations, but their bankfull landform patterns appear to have coalesced with coherent width and bed elevation undulations during flood flows. Finally, metrics for confined river types showed that it takes higher magnitude, less frequent floods to set their coherent width and bed elevation undulations, but even these channels do exhibit flow convergence routing when given enough discharge for sufficient duration.

Estuarine environmental flow assessment based on the flow-ecological health index relation model: a case study in Yangtze River Estuary, China.

Environmental flow (e-flow) is the water demand of one given ecosystem, which can become the flow regulation target for protection and restoration of river or estuarine ecosystems. In this study, an e-flow assessment based on the flow-ecological health index (EHI) relation model was conducted to improve ecosystem health of the Yangtze River Estuary (YRE). Monitoring data of hydrology, biology, and water environment in the last decades were used for the model establishment. For the description of the YRE ecosystem, an EHI system was developed by cumulative frequency distribution curves and adaption of national standards. After preprocessing original flow values into proportional flow values, the generalized additive model and Monte Carlo random sampling were used for the establishment of the flow-EHI relation model. From the model calculation, the e-flow assessment results were that, in proportional flow values, the suitable flow range was 1.05-1.35, and the optimum flow range was 1.15-1.25 (flows in Yangtze River Datong Station). For flow regulation in two crucial periods, flows of 42,630-65,545 m3/s or over 14,675 m3/s are needed for the suitable flow of YRE in summer (June-August) or January, respectively. An adaptive management framework of ecological health-based estuarine e-flow assessment for YRE was contrived due to the limitation of current established model when facing the extreme drought in summer, 2022. The methodology and framework in this study are expected to provide valuable management and data support for the sustainable development of estuarine ecosystems and to bring inspiration for further studies at even continental or global levels.

Evaluating effectiveness of restoration to address current stressors to riverine fish

Abstract River restoration programmes with the goal of conserving and rehabilitating inland fishes have a multi‐decadal history, but evaluation and synthesis of past restoration actions have been limited by a lack of monitoring and reporting. Given that calls for both monitoring and systematic reviews of restoration have increased, we were interested in the influence that restoration has had on improving conditions for riverine fishes resulting from long‐standing and increasingly prominent stressors. Our objectives were to (1) identify which stressors were targeted in river restoration efforts, (2) determine the proportion of published studies that articulate restoration goals and develop comparative monitoring designs for assessing the effects of restoration on fishes, and (3) conduct a meta‐analysis to synthesise fish responses to restoration projects. We assessed restoration effectiveness for increasing fish density and richness from peer‐reviewed papers published over the past decade using a global systematic review and meta‐analysis. We found that restoration actions addressed major stressors primarily by improving in‐stream habitat (37%), increasing in‐stream longitudinal connectivity (26%) and increasing lateral floodplain connections (9%). Although 81% of studies had comparative monitoring designs (i.e., before/after and control/impact) and stated restoration goals, only 40% of those studies reported sufficient data to be included in the meta‐analysis. Projects which increased in‐stream connectivity had the largest positive effect size on fish density and richness compared to in‐stream habitat improvements and increasing floodplain connections. Time since restoration and restoration size (i.e., geographical footprint) were not strong predictors of fish response effect sizes. Restoration effectiveness was highly variable among project types. Authors of studies included in the meta‐analysis often identified spatial or temporal scale of monitoring, overriding catchment conditions, and recolonisation potential as sources of variability and effectiveness in restoration outcomes. Systematic reporting of these and other covariates may help guide processes in restoration evaluation and provide valuable research insights. Despite increased emphasis on monitoring, incomplete data reporting limited the number of studies that could be included for quantitative meta‐analysis. Persistent emphasis on setting specific criteria (e.g., measurable outcomes of fish response) for restoration goals, project monitoring, data reporting, information sharing and collaborative projects is likely to continue to improve understanding of restoration effectiveness transferable to future endeavours. Our results can be used to support river restoration practitioners with evidence‐based information to evaluate the cost–benefit ratio of competing restoration priorities, and inform restoration planning and implementation for riverine fish.

Effects of Revetments on Nitrification and Denitrification Potentials in the Urban River–Riparian Interface

River–riparian interfaces (RRIs) are not only an important type of urban land but also a key area for mitigating and controlling urban river nitrogen pollution. However, the material and energy exchange dynamics in the natural interaction between rivers and RRIs undergo changes due to the introduction of recently constructed revetments, affecting the nitrogen cycling of the RRI, and the impact of revetments on the control and mitigation of river nitrogen pollution in an RRI is unknown. Therefore, RRI soil properties, nitrification potentials (NPs), and denitrification potentials (DPs) were measured in natural, permeable, and impervious revetments in this study. Furthermore, structural equation models were developed to investigate the potential mechanism of the revetment’s impact on RRI NPs and DPs. The NPs of the natural revetment (NR) (7.22 mg/(kg·d)) were 2.20 and 2.16 times that of the impervious revetment (IR) and permeable revetments (PRs), respectively. The most important influencing factors of NPs were the aboveground biomass (AB) and available nitrogen. Similarly, the denitrification potential (DP) of the PR was 3.41 and 2.03 times that of the NR (22.44 mg/(kg·d)) followed by the IR (37.59 mg/(kg·d)). Furthermore, the AB had the greatest direct and total benefit on the DP, and nitrate may be a factor limiting the denitrification process. A revetment primarily disturbs the anaerobic environment and soil properties at RRIs, as well as changing the nitrification and denitrification potentials via soil erosion, solute exchange, and dry–wet alternation. These research results furnish a theoretical foundation for the restoration of urban rivers’ ecology and additionally provide benchmarks for sustainable development in urban areas.

Enhanced flow variability and morphological changes through individual wood placements on a gravel bed

To design and evaluate river restoration projects with wood, it is crucial to understand how the placement of wood will alter flow and bed morphology. This information is still missing. To address this, flume experiments were conducted with a single log placed on a mobile bed with a uniform grain size. The effect of log diameter, log orientation to the flow, and log length on flow variability and bed morphology was studied for various initial flow conditions. Even a single log increased flow variability, herein defined as spatial variability in both velocity and turbulent kinetic energy. For each log placed at the channel center, the logs generated a symmetric scour pattern alongside and downstream of the log due to increased bed shear and turbulence generated by the log. A steady, adjusted cross-section was reached at the cessation of erosion, which occurred when the bed stress decreased below the critical shear velocity. Logs with larger diameter tended to erode more deeply, so that the final, adjusted cross-section was similar for different log dimensions. Changes in bed topography affected wake characteristics. Logs with small changes in bed topography generated longer zones of reduced velocity, which can increase the residence time of organic matter or nutrients in the wake region. Logs with big changes in bed topography created the deepest and longest scour holes, which may locally reduce stream temperature and improve fish habitat during summer.

River networks evolution under multiple stresses: A geometric and structural fractal perspective

Accurately quantifying changes in river networks is essential for studying and assessing the environmental effects of such changes. The fractal method has become a popular and effective tool for describing and capturing river network changes. However, it is usually limited to the geometric fractal dimension (Dg), whereas the structural fractal dimension (Ds) is rarely used. Despite this, the Ds could capture crucial structural information, which the Dg does not, such as interconnections among rivers and the overall basin connectivity. In this study, we examined the evolution of Dg and Ds in the Qinhuai River Basin from the 1960s to 2016, revealing the changes in river networks under natural and anthropogenic stresses from both the traditional geometric and novel structural fractal analysis perspective. We also determined the key factors causing fractal variation and their contributions. The results showed that river networks possess both structural and geometric fractality, with values ranging from 1.484 to 1.287 and 1.615–1.514, respectively. The values of Dg and Ds both declined, with Ds declining at a higher rate, suggesting that the river network weakened and deteriorated. The variances of Dg and Ds attributed to urbanization were 0.3139 and 0.3103, respectively, more than thirty times and almost twice as much as the variance attributed to precipitation features. Urbanization was identified as the most significant factor influencing fractal dynamics. These findings advance the understanding of river network evolution from a novel fractal perspective and provide support for integrating river restoration with urban planning practices.

Hedonic analysis of willingness to pay for dam removal: evidence from Plymouth, Massachusetts

This study investigates how the removal of small dams, and subsequent river restoration investments, affect residential housing prices in Plymouth, Massachusetts, selected for its unusually high density of dam removals. From 2002 to 2019, 5 dams within 1.05 miles of each other have been removed. Following removal, riverine restoration was completed, leading to improved public safety for downstream infrastructure, fish passage, and better water quality. Yet, contention exists in local government decision-making from fear of loss of property values of homes that are no longer classified as “waterfront.” To examine that charge, we evaluate sale prices of 9,710 single-family homes from 1997 to 2021, in a comparative estimation of a hedonic regression and a difference in differences model. The results indicate that the price of homes sold in Plymouth after dam removal increased, with no impact on property values of waterfront and properties within 1 mile of riverine restoration locations. For properties within a 5-mile radius of a former dam, we observe comparative difference in price of a fraction of a percent for lots around 2 of the dams, in relation to all home lots in Plymouth. We explain that this difference is due to property-specific features, rather than the impact of dam removal. The implications are that dam removal would not negatively impact waterfront property values, while it may translate into an overall environmental price premium for the community at large.

Modelling of potential vegetation identifies diverging expectable outcomes of river floodplain widening

River re-naturalisations are at the forefront of conservation efforts. The hope is that these interventions will benefit both local ecosystems and facilitate flood mitigation. While hydrological modelling has been a standard procedure in assessing the outcomes of river re-naturalisations, vegetation modelling has not always been performed as part of these assessments. We hypothesised that the use of potential vegetation modelling, i.e. the modelling of self-sustainable vegetation that can survive after the intervention, can provide insight into vegetation outcome of river re-naturalisation and can thus support vegetation restoration and conservation planning. We investigated the utility of potential vegetation modelling under a specific, widespread element of river re-naturalisation: river floodplain widening at three study sites along the Tisza River in Hungary. We applied potential vegetation modelling, in addition to hydrological and groundwater modelling, to assess the expected vegetation outcome of the river floodplain widening. Flood frequency and duration were assessed by the HEC-RAS hydrological model. Based on the output this hydrological model provided, expected values of the water-related explanatory variables (including groundwater level) were calculated. Statistical relationships encompassed by the existing mulitple potential vegetation (MPV) models of Hungary were applied to the environmental variable sets corresponding to conditions before and after floodplain widening (pre- and post-treatment, respectively), including water-related and other explanatory variables. This resulted in predicted potential vegetation distribution for pre-treatment and post-treatment conditions, which were then compared via ordinations and PERMANOVA. At two of the study sites, post-treatment potential vegetation prediction typically showed vegetation types requiring wetter and less saline conditions when compared to the pre-treatment potential vegetation distribution. This pattern corresponds to general expectations given river floodplain widening. However, at one of the sites, the potentiality of saline and non-saline steppe vegetation was actually more pronounced under the expected post-treatment conditions than those before widening. The strengthening of the potentiality of dry vegetation types can be explained by the minor environmental differences related to the microrelief. As the studied sites were all located in the lowlands where geomorphological variation is small, the effect of these minor geomorphological differences on post-treatment potential vegetation would have remained hidden without applying MPV models. In conclusion, scenarios that employ MPV models help predict river restoration outcomes more accurately and can help identify factors that might otherwise be overlooked. Thus, when combined with physical modelling of river flow, their use can aid in the restoration and landscape planning decisions in river re-naturalisation projects.