River Rehabilitation Research Articles

Management of alien fishes in the Murray‐Darling Basin

SummaryNative Fish Strategy 2003–2013 (NFS) investment over the past decade has considerably improved alien fish management for the Murray‐Darling Basin. The NFS delivered a wide and varied portfolio of activities on alien fish management – planning, social aspects, on‐ground management and a major investment in research. Control of Carp (Cyprinus carpio) was a key feature; however approaches moved beyond this one species to address multiple species and to take a more holistic approach, advocating integrated pest management and linking alien fish with native fish management and broader river rehabilitation. The NFS provided leadership for the management of alien fish in the Basin and established a framework to guide future efforts in this field through the development of a draft Basin Alien Fish Plan.

Cost-effective river rehabilitation planning: Optimizing for morphological benefits at large spatial scales

River rehabilitation aims to protect biodiversity or restore key ecosystem services but the success rate is often low. This is seldom because of insufficient funding for rehabilitation works but because trade-offs between costs and ecological benefits of management actions are rarely incorporated in the planning, and because monitoring is often inadequate for managers to learn by doing. In this study, we demonstrate a new approach to plan cost-effective river rehabilitation at large scales. The framework is based on the use of cost functions (relationship between costs of rehabilitation and the expected ecological benefit) to optimize the spatial allocation of rehabilitation actions needed to achieve given rehabilitation goals (in our case established by the Swiss water act). To demonstrate the approach with a simple example, we link costs of the three types of management actions that are most commonly used in Switzerland (culvert removal, widening of one riverside buffer and widening of both riversides) to the improvement in riparian zone quality. We then use Marxan, a widely applied conservation planning software, to identify priority areas to implement these rehabilitation measures in two neighbouring Swiss cantons (Aargau, AG and Zürich, ZH). The best rehabilitation plans identified for the two cantons met all the targets (i.e. restoring different types of morphological deficits with different actions) rehabilitating 80,786 m (AG) and 106,036 m (ZH) of the river network at a total cost of 106.1 Million CHF (AG) and 129.3 Million CH (ZH). The best rehabilitation plan for the canton of AG consisted of more and better connected sub-catchments that were generally less expensive, compared to its neighbouring canton. The framework developed in this study can be used to inform river managers how and where best to spend their rehabilitation budget for a given set of actions, ensures the cost-effective achievement of desired rehabilitation outcomes, and helps towards estimating total costs of long-term rehabilitation activities. Rehabilitation plans ready to be implemented may be based on additional aspects to the ones considered here, e.g., specific cost functions for rural and urban areas and/or for large and small rivers, which can simply be added to our approach. Optimizing investments in this way will ultimately increase the likelihood of on-ground success of rehabilitation activities.

A probabilistic approach for the socioeconomic assessment of urban river rehabilitation projects

Urban river rehabilitation aims to enhance the ecological status of urban watercourses and promote measures for the local population to increase their well-being by making a direct or indirect use of the services these ecosystems may provide. The social and economic feasibility is evaluated by contrasting the resources used in the rehabilitation process with the benefits derived from it through the Cost-Benefit Analysis (CBA). By means of a case study, this work not only introduces the most innovative CBA approaches in environmental projects, but also implements probabilistic simulation methods in order to increase the robustness of the assessment indicators.The case study encompasses two projects, whose global costs total €46M in 50 years, for the environmental rehabilitation of the stretch of the River Segura that flows through the city of Murcia. The benefits have been obtained by a contingent valuation exercise: €3.3M/year (€0.6M/year of use benefits, and €2.7M/year of non-use benefits). Three different CBA approaches (economic, extended and dual) are applied to contrast these costs and benefits, conducting the analyses of uncertainty and sensitivity of the benefit items through a Monte Carlo simulation. The results highlight the importance of environmental benefits for this kind of projects to be socioeconomically feasible thanks to the profitability indicators they provide.

Multi-scalar controls on channel geometry of headwater streams in New Zealand hill country

Catchment-, reach-, and local-scale controls upon channel geometry are examined for small headwater streams in adjacent sub-catchments with variable land use histories in a typical hill country area of the North Island of New Zealand. Although systematic downstream increase in channel cross-sectional area is evident in one sub-catchment (a result of catchment-scale controls on geometry, including discharge and slope), marked local variability in channel geometry in the two other sub-catchments reflects non-systematic patterns of reach-scale controls including the distribution of floodplain pockets and associated bank materials, and local-scale controls such as bedrock outcrops and wood. Land use change exerts a primary control upon these relationships. For a given catchment area, streams in native forest are wider and shallower than streams that flow within pasture or Pinus plantations. Increased hillslope erosion following land clearance has instigated the accumulation of post-settlement alluvium (PSA), which has altered the boundary conditions and bank materials within which streams flow. Significant PSA accumulation following native forest clearance in one of the sub-catchments has allowed the stream to flow entirely within its own alluvial deposits. In this instance, catchment-scale controls on channel geometry are dominant. In contrast, local-scale controls on channel geometry are more important in the other sub-catchments where lesser accumulation of PSA reflects differences in land clearance. These findings indicate that place-based understandings which consider the spatial and historical contexts of landscape settings are required to interpret patterns of channel geometry, and to inform river rehabilitation initiatives.

Stormwater quality modeling for upscaling MSMA stormwater management ecohydrology

Langat River is 180 km length has a total catchment area of 2,350 km2. The Langat River is classified as Class II in the upstream, and as the water flows downstream the quality degrades to Class III and IV. This degradation is caused by the rapid and uncontrolled urbanization in the contributing catchment of the river. The characteristics of the river and its contributing catchment are modeled using Model for Urban Stormwater Improvement Conceptualisation (MUSIC) in order to rehabilitate the river and enhance its Water Quality Index (WQI) to Class II. The historical rainfall data was obtained from DID for the period from 1974 to 2012. This paper presents the effects of various BMP Components on rehabilitating the water quality of the river. In addition, the minimum amount of river flow required for protection of the habitats and the river's ecology has been assessed during the dry seasons. The outcomes of this study suggest the most appropriate Best Management Practices that can be used as solutions for the river's rehabilitation. Simulations and modeling result found out that a configuration of wetlands, bio-retention systems and ponds are capable to reduce pollutants loadings such as TSS, TP and TN by 85.1%, 69.1% and 37.5% respectively

FIDIMO — A free and open source GIS based dispersal model for riverine fish

Dispersal is a key process in community ecology and dynamics that comprise not only various movement processes, but also behavioural components and large-scale spatio-temporal patterns. Modelling fish dispersal further has to consider the species-specific dispersal abilities and the branching, dendritic nature of river networks.With FIDIMO (fish dispersal model) a tool is provided for predicting and simulating spatio-temporal patterns of fish dispersal in river networks with a real integration of GIS for the first time. The model has been written in Python programming language as open source add-on for GRASS GIS. The model has been developed to apply the characteristics of heterogeneous, species and size class specific fish movement on a rasterized river network including migration barriers. Fish dispersal is modelled as a leptokurtic diffusion process spreading from spatially predefined source populations consisting of stationary and mobile components each. The fish dispersal model FIDIMO links conceptual considerations on dispersal modelling with empirically observed fish movement patterns and the strengths of geographically explicit modelling in FOSS GIS. It can be used for different species and any river network meeting the input requirements.As main results FIDIMO yields probabilities of occurrence of fish species in river raster cells based on empirically derived dispersal kernels after the time step of interest modelled.The model output serves to understand and predict time lags and spatio-temporal patterns of recolonization events, the related success of river rehabilitation and also the spread of invasive species. The consequent use of open source programmes allows free access to the code and facilitates easy modifications, adoptions and improvements of the model.

HIGH-FLOW GRAVEL INJECTION FOR CONSTRUCTING DESIGNED IN-CHANNEL FEATURES

A planned gravel bar was dynamically constructed at a river rehabilitation project site through a combination of mechanical channel reconfiguration and high-flow gravel injection. Mechanical alterations intended to promote deposition in a target area were followed by the injection of 1570 m3 of gravel and small cobble 400 m upstream during a high-flow dam release. This dynamic bar construction proved successful in that bed elevations increased locally by more than 1 m in the target area and a new alternate bar sequence was created nearby. Morphodynamic modelling used to plan the injection correctly identified general areas prone to deposition or scour, but did not correctly predict the magnitudes of change or resolve features at the scale of individual alternate bars. A flow perturbation induced by a constructed meander bend just upstream from the injection point may have contributed to alternate bar development. Despite the observed bar development, sediment budget calculations indicate that the quantity of gravel stored in the target reach remained constant, perhaps because of an interruption in the delivery of bed material from upstream. The estimated gravel load over the release increased steadily in the downstream direction and, at the downstream study area boundary, had attained a magnitude 4.6 times larger than the quantity of injected gravel. These results demonstrate that bedload entrainment from the channel perimeter dominated the gravel supply to downstream reaches and suggest that the gravel injection had little effect on geomorphic adjustments downstream from its target area. Copyright © 2013 John Wiley & Sons, Ltd.

River rehabilitation for the delivery of multiple ecosystem services at the river network scale

This paper presents a conceptual framework and methodology to assist with optimising the outcomes of river rehabilitation in terms of delivery of multiple ecosystem services and the benefits they represent for humans at the river network scale. The approach is applicable globally, but was initially devised in the context of a project critically examining opportunities and constraints on delivery of river rehabilitation in Scotland. The spatial-temporal approach highlighted is river rehabilitation measure, rehabilitation scale, location on the stream network, ecosystem service and timescale specific and could be used as initial scoping in the process of planning rehabilitation at the river network scale. The levels of service delivered are based on an expert-derived scoring system based on understanding how the rehabilitation measure assists in reinstating important geomorphological, hydrological and ecological processes and hence intermediate or primary ecosystem function. The framework permits a “total long-term (>25 years) ecosystem service score” to be calculated which is the cumulative result of the combined effect of the number of and level of ecosystem services delivered over time. Trajectories over time for attaining the long-term ecosystem service score for each river rehabilitation measures are also given. Scores could also be weighted according to societal values and economic valuation. These scores could assist decision making in relation to river rehabilitation at the catchment scale in terms of directing resources towards alternative scenarios. A case study is presented of applying the methodology to the Eddleston Water in Scotland using proposed river rehabilitation options for the catchment to demonstrate the value of the approach.Our overall assertion is that unless sound conceptual frameworks are developed that permit the river network scale ecosystem services of river rehabilitation to be evaluated as part of the process of river basin planning and management, the total benefit of river rehabilitation may well be reduced. River rehabilitation together with a ‘vision’ and framework within which it can be developed, is fundamental to future success in river basin management.

Ecological effects of rehabilitation measures at the Austrian Danube: a meta-analysis of fish assemblages

Large rivers are worldwide under severe pressure and there is a lack of information on large river restoration. The present paper represents a meta-analysis of available data on river rehabilitation projects performed at the Austrian Danube River consisting of six rehabilitation projects addressing 19 sites. The overall goal was to analyse the response of fish assemblages to different rehabilitation types based on (1) morphological type (“Instream Habitat Enhancement”, “backwater Enhancement”, “extended Enhancement”), (2) length of rehabilitation measure (3) time after construction (4) applied monitoring design. Biological metrics evaluated included number of fish species and relative density, habitat guilds and Leitbild species. In total, number of species increases by 55% comparing rehabilitated with unrestored sites. The number of species of all habitat guilds is higher after rehabilitation. The proportion of rheophilic species increased and the community evolved toward a more type-specific community, according to the Leitbild. Significant differences between measure types were not detected. The rehabilitation success depends mainly on its spatial extent. Highest positive response of number of rheophilic species is achieved by a length >3.9 km. The results show that habitat rehabilitation of large rivers is effective if the spatial extent of the measure is in accordance with river size.

Revisiting the River Skerne: The long-term social benefits of river rehabilitation

This article compares the results from three public perception surveys concerning the rehabilitation of the River Skerne in Darlington, NE England. It discusses people's perception over time, from pre-rehabilitation expectations to initial impression of the rehabilitation to their opinions of the matured project in a longer term perspective. It is one of the few studies in the UK to include pre-, post- and long-term assessments for the same area. The green environments riverscapes provide, especially in urban spaces, have positive effects on people's well-being and are appreciated as areas for relaxation and recreation. However, the over exploitation of riverscapes has dramatically decreased their function, the ecosystem services they provide and the connection between people and nature. Results from our surveys indicate that with careful design considering both social and ecosystem values, and wider collaboration between science and social science, river rehabilitation works can re-establish riverscapes that provide attractive recreational spaces without losing their possibilities to sustain healthy ecosystems. Ecosystem recovery is a long and time consuming process, but this research shows that it also takes time for people to build up a caring and emotional connection to their local riverscapes. This process can be aided by common vision building and attending to features providing possibilities for recreation and access, and attractive greenery. We conclude that by applying a transparent process for rehabilitation schemes, with a clear social and environmental focus, we increase our chances of providing long-term benefits and receiving public support for enhancing the state of our rivers.

Hydromorphological implications of local tributary widening for river rehabilitation

The hydromorphological implications of the local widening of a tributary where it enters a confluence were investigated in a laboratory setting that is representative of the 20 major confluences on the channelized Upper Rhone River. Although local tributary widening reduces the confluence angle, it amplifies the hydromorphosedimentary processes in the confluence hydrodynamic zone (CHZ), because local widening reduces the effective flow area, causing increased tributary velocities and momentum flux. The reduction in effective flow area is caused by an increase in bed elevation and by lateral constriction of the flow induced by flow stagnation at the upstream corner of the confluence. The increased tributary velocities amplify the two‐layer flow structure in the CHZ. Flow originating from the tributary is confined to the upper part of the water column and is more markedly directed outward than flow in the lower part of the water column originating from the main channel. A shear layer characterized by increased turbulence activity develops at the interface between the two flow layers. The increased tributary velocities enhance bed discordance, the penetration of the tributary into the CHZ and the channel bed gradients in the postconfluence channel. The results indicate that local tributary widening can enhance heterogeneity in sediment substrate, flow velocities and flow depths. Widening may therefore enhance local habitat and improve the connectivity of the tributary to the main river network. This may, in turn, provide favorable conditions for the improvement and reestablishment of ecological river functions, without having adverse impact on flood safety.

Uncertainty Improvement in a Simulation of Channel Evolution

The Four Major Rivers Restoration Project (4MRRP), one of the largest river rehabilitation projects in Korea, has being carried out during the last three years. 0.57 billion m3 of sediment was dredged to widen and deepen the channel along four major rivers, the Han, Nakdong, Geum, and Youngsan rivers. As a result of reshaping the natural channel to a trapezoidal channel, and the construction of 16 weirs, the change of longitudinal slope of the river was inevitable. The distribution of bed materials was also changed, due to dredging. Therefore, the rivers were totally disturbed, and the stability of the rivers could not be assured. In particular, the Nakdong river, the second largest river in Korea, has the characteristics of an alluvial channel. Degradation of the main channel bed caused bank erosion, and head-cut phenomena in many tributaries. Deformations of the main channels could be observed all along the river. Long-term simulation of the channel evolution and prediction of the stability of the Nakdong river have to be examined, to cope with the instability of the river, which could lead to unexpected river disasters. This study deals with the methodology of uncertainty improvement, in analysis of the simulation and confirmation with field survey data. Methodology of uncertainty improvement in description of weir, whose discharge coefficient is unknown, in a river was suggested.

Water, Wind, Wood, and Trees: Interactions, Spatial Variations, Temporal Dynamics, and their Potential Role in River Rehabilitation

AbstractRecent Australian research has quantified the role of large wood (wood of any origin and length with a diameter greater than 0.1 m) in dissipating stream energy, forming pool habitats by local bed scour, protecting river banks from erosion, and damming rivers with long rafts causing avulsions. Large wood in Australian streams is sourced by a range of processes from the nearby riparian zone which has usually been degraded by post‐European settlement vegetation clearing. Large wood loadings within the bankfull channel are dependent not only on the type and quality of the riparian plant community but also on bankfull specific stream power, channel width, and the processes of large wood delivery to the stream. While bank erosion and floodplain stripping by catastrophic floods are obvious and important delivery mechanisms, treefall and trunk and branch breakage by strong winds during tropical cyclones and severe storms are also significant in the tropics. Furthermore, wood decay and downstream transport produce temporally dynamic large wood distributions. The longevity of natural large wood structures in rivers, such as rafts, debris dams, and log steps, requires determination. River rehabilitation programs need to not only include the reintroduction of large wood, but also carefully plan the spatial distribution of that wood, the most appropriate type and range of large wood structures, and, most importantly, the revegetation of the riparian zone to ensure a natural long‐term source of large wood. Exotic species management is an essential part of river rehabilitation.

Effects of streamflow variability on the vertical root density distribution of willow cutting experiments

The use of riparian tree cuttings for river rehabilitation relies on a good understanding of cutting survival and growth responses to environmental variables. A series of experiments aimed at studying the effects of water table fluctuation induced by streamflow variability on the development of below-ground biomass of riparian tree cuttings was performed on the Thur River (Switzerland). White willow (Salix alba) cuttings were installed in gravel bar plots at various locations to develop an understanding of how topography and flow variability control cutting root development strategies, which in turn can lead to observed different vertical root density distributions in response to varying forms of tropism. In particular, we show that the transient root growth dynamics, eventually create a distribution reflecting the hydrologic conditions experienced towards the end of the growing season. A scaling relationship is presented that is useful to predict the expected depth with the highest root density as a function of soil topography and river discharge statistics. The results have implications for predicting cutting survival and growth, along with a corresponding strengthening of the alluvial sediment, in different flow regimes. This approach is therefore useful to incorporate in morphodynamic models covering the ecological and hydraulics responses of below-ground biomass to floods.

Development of Bayesian Network Decision Support Tools to Support River Rehabilitation Works in the Lower Snowy River

ABSTRACT Community concern at the continual environmental decline of the Snowy River (New South Wales and Victoria, Australia) has resulted in a substantial investment in river rehabilitation works, referred to as the Snowy Rehabilitation Project. Much of the investment in the science component of the project went into developing physical models to better understand the behavior of sediments that have accumulated over time in the river channel. The outcomes of these models were intended to assist river managers in better controlling sediment impacts to restore instream ecological function. To synthesize the learnings from these studies for use by catchment managers, a simple decision support tool, referred to as the Snowy tool, was constructed. The Snowy tool was designed to link outcomes from the models with management activities (or interventions) to outcomes within the river channel. It took the form of a probabilistic model (Bayesian network) that incorporates data from a hydraulic model (HEC-RAS), combined with expert opinion, and riverine response models. This article overviews the Snowy tool, and stresses the importance of the use of Bayesian networks in adaptive management frameworks and in guiding investments in research and on-ground decision-making.

Differences in sensitivity of native and exotic fish species to changes in river temperature

Abstract This paper describes the effects that temperature changes in the Rhine river distributaries have on native and exotic fish diversity. Site-specific potentially affected fractions (PAFs) of the regional fish species pool were derived using species sensitivity distributions (SSDs) for water temperature. The number of fish species in the river distributaries has changed remarkably over the last century. The number of native rheophilous species declined up until 1980 due to anthropogenic disturbances such as commercial fishing, river regulation, migration barriers, habitat deterioration and water pollution. In spite of progress in river rehabilitation, the native rheophilous fish fauna has only partially recovered thus far. The total number of species has strongly increased due to the appearance of more exotic species. After the opening of the Rhine-Main-Danube waterway in 1992, many fish species originating from the Ponto-Caspian area colonized the Rhine basin. The yearly minimum and maximum river temperatures at Lobith have increased by circa 4 0C over the period 1908-2010. Exotic species show lower PAFs than native species at both ends of the temperature range. The interspecific variation in the temperature tolerance of exotic fish species was found to be large. Using temporal trends in river temperature allowed past predictions of PAFs to demonstrate that the increase in maximum river temperature negatively affected a higher percentage of native fish species than exotic species. Our results support the hypothesis that alterations of the river Rhine’s temperature regime caused by thermal pollution and global warming limit the full recovery of native fish fauna and facilitate the establishment of exotic species which thereby increases competition between native and exotic species. Thermal refuges are important for the survival of native fish species under extreme summer or winter temperature conditions.

A spatial assessment of riverine ecosystems and water supply in a semi‐arid environment

AbstractA spatial assessment was conducted in the semi‐arid area of South Africa, to: (1) identify priority areas for the conservation of river and groundwater ecosystems; (2) examine surface and groundwater quality for human consumption and (3) investigate the rehabilitation of degraded areas to highlight ‘win‐win’ situations for both environmental and human use. A systematic conservation plan was produced, highlighting river conservation areas (river types, fish species and connectivity areas), moderate‐impact management areas (groundwater‐surface water interaction and recharge areas) and river rehabilitation areas. The proposed river selections would achieve the biodiversity targets of 33 (66%) of the 50 river types; feasible rehabilitation would increase this to 92%. The greatest groundwater‐surface water interaction and recharge (30 to > 50 mm−1) values are concentrated around the mountainous regions of the Little Karoo. This is because the main aquifers in the mountains, table mountain group (TMG) quartzites, yield naturally good quality water for human consumption. River reaches of unacceptable surface water quality were classified as degraded water resource delivery areas where the poor water quality was primarily due to saline return flows from irrigation and the impacts of other anthropogenic activities including abstraction of freshwater which otherwise would have diluted the return flows. Only the middle reaches of the Gouritz and Groot Rivers represent a possible win–win situation for both the environment and human use. Copyright © 2010 John Wiley & Sons, Ltd.

Systematic planning for river rehabilitation: integrating multiple ecological and economic objectives in complex decisions

Summary1. Owing to intensive human use, freshwaters are among the most seriously threatened and modified environments on the planet. Their poor condition and the risk to services that humans need from these ecosystems make their rehabilitation a priority. However, many previous studies have reported the poor performance of many rehabilitation activities.2. Here, we analyse reasons for this poor performance, focussing on the planning of rehabilitation activities, and propose a new approach. We argue that the failure to include driving factors at a scale adequate to capture the ecological processes involved, together with an insufficient incorporation of socio‐economic aspects, is a key factor leading the poor performance of many rehabilitation activities.3. We propose a new approach, ‘systematic rehabilitation planning’, that brings together advances made in conservation planning (cost‐effectiveness analysis) and ecosystem science (understanding the complexity of ecosystem processes). This enables planning to be done at the catchment scale, and the trade‐offs between various rehabilitation actions to be integrated and prioritised.4. Finally, it is important, given the constraints imposed by a lack of knowledge, that the planning process is part of an adaptive cycle where it can benefit from and consolidate the experience gained during the implementation and monitoring stages.

Development, validation, and application of a macroinvertebrate-based Index of Biotic Integrity for nonwadeable rivers of Wisconsin

Quantitative biological assessment protocols are needed for monitoring river status and evaluating river rehabilitation efforts. We conducted a standardized macroinvertebrate survey at 100 sites on 38 nonwadeable rivers in Wisconsin to construct, test, and apply an index of biotic integrity (IBI) intended to be such a bioassessment tool. We assigned independent samples to IBI development (n = 75) and IBI validation (n = 25) data sets. We placed Hester–Dendy artificial substrates at the sites for 6 wk and processed the samples of colonizing macroinvertebrates in the laboratory with a 500-target subsampling procedure plus a large–rare taxon search. Independent of the biota, we assigned an environmental disturbance score to each site based upon water chemistry, land cover, flow modification, and point-source pollution. Ten metrics that represent macroinvertebrate assemblage structure, composition, and function constitute the IBI: the number of taxa in: 1) Insecta or 2) Ephemeroptera, Plecoptera, Trichoptera (EPT); % individuals that were: 3) Insecta, 4) intolerant EPT, 5) tolerant chironomids, 6) gatherers, 7) scrapers, or from 8) the dominant 3 taxa; 9) the mean pollution tolerance value; and 10) the number of unique ecological functional trait niches. Analyses on both the validation subset of sites and all sites inclusive confirmed that least-disturbed sites had the highest IBI scores, severely disturbed sites had the lowest scores, and moderately disturbed sites had intermediate scores. Chironominae and Hydropsychidae taxa known to tolerate nutrient enrichment and overall degraded conditions dominated samples with low IBI scores. In contrast, a diverse assemblage that thrives in relatively undisturbed conditions was present in samples with high IBI scores. Comparison of the new macroinvertebrate IBI with an existing fish IBI suggested that the indices respond to different environmental stressors and illustrated the limitations of using only one taxonomic group for bioassessment. We discuss new macroinvertebrate methods, an IBI development process, and the refinement of metrics that may be useful in tailoring assessment tools for large rivers or wadeable streams in other regions. We also present applications of the IBI, including its potential use in comprehensive large river monitoring programs and for evaluating management efforts.

A Bayesian network model for integrative river rehabilitation planning and management

As rehabilitation of previously channelized rivers becomes more common worldwide, flexible integrative modeling tools are needed to help predict the morphological, hydraulic, economic, and ecological consequences of the rehabilitation activities. Such predictions can provide the basis for planning and long-term management efforts that attempt to balance the diverse interests of river system stakeholders. We have previously reported on a variety of modeling methods and decision support concepts that can assist with various aspects of the river rehabilitation process. Here, we bring all of these tools together into a probability network model that links management actions, through morphological and hydraulic changes, to the ultimate ecological and economic consequences. Although our model uses a causal graph representation common to Bayesian networks, we do not limit ourselves to discrete-valued nodes or conditional Gaussian distributions as required by most Bayesian network implementations. This precludes us from carrying out easy probabilistic inference but gives us the advantages of functional and distributional flexibility and enhanced predictive accuracy, which we believe to be more important in most environmental management applications. We exemplify model application to a large, recently completed rehabilitation project in Switzerland.