MODELLING CHANGES IN SALMON HABITAT ASSOCIATED WITH RIVER CHANNEL RESTORATION AND FLOW‐INDUCED CHANNEL ALTERATIONS

The River2D two‐dimensional hydraulic and habitat model was used to simulate fall‐run Chinook salmon (Oncorhynchus tschawytscha) spawning and fry and juvenile rearing habitat of the first phase of a stream channel restoration project on Clear Creek, California. Habitat was simulated for a range of stream flows: (1) before restoration; (2) based on the restoration design; (3) immediately after restoration; and (4) after one and two large flow events. Hydraulic and structural data were collected for three sites before restoration, and prerestoration habitat was simulated. Habitat simulated for these sites was extrapolated to the prerestoration area based on habitat mapping. The topographical plan for the restoration was used to simulate the anticipated habitat after restoration. Although the restoration increased spawning habitat, it was less successful for rearing habitat. Channel changes associated with high‐flow events did not entirely negate the benefits of the restoration project. The results of this study point out the need for models that can simulate the changes in channel topography associated with high‐flow events, which could then be used to simulate habitat over time. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.     

RESTORING SALMON HABITAT FOR A CHANGING CLIMATE

An important question for salmon restoration efforts in the western USA is ‘How should habitat restoration plans be altered to accommodate climate change effects on stream flow and temperature?’ We developed a decision support process for adapting salmon recovery plans that incorporates (1) local habitat factors limiting salmon recovery, (2) scenarios of climate change effects on stream flow and temperature, (3) the ability of restoration actions to ameliorate climate change effects, and (4) the ability of restoration actions to increase habitat diversity and salmon population resilience. To facilitate the use of this decision support framework, we mapped scenarios of future stream flow and temperature in the Pacific Northwest region and reviewed literature on habitat restoration actions to determine whether they ameliorate a climate change effect or increase life history diversity and salmon resilience. Under the climate change scenarios considered here, summer low flows decrease by 35–75% west of the Cascade Mountains, maximum monthly flows increase by 10–60% across most of the region, and stream temperatures increase between 2 and 6°C by 2070–2099. On the basis of our literature review, we found that restoring floodplain connectivity, restoring stream flow regimes, and re‐aggrading incised channels are most likely to ameliorate stream flow and temperature changes and increase habitat diversity and population resilience. By contrast, most restoration actions focused on in‐stream rehabilitation are unlikely to ameliorate climate change effects. Finally, we illustrate how the decision support process can be used to evaluate whether climate change should alter the types or priority of restoration actions in a salmon habitat restoration plan. Copyright © 2012 John Wiley & Sons, Ltd.     

FISH ASSEMBLAGES RESPOND TO HABITAT AND HYDROLOGY IN THE WABASH RIVER,INDIANA

Detailed relationships between fish assemblages and habitat and hydrology variation are largely unknown for large rivers. We evaluated hydrology, habitat variation and fish assemblages at 28 sites on the Wabash River, Indiana, USA, during 2005–2008. We calculated hydrologic variation with the Indicators of Hydrologic Alteration software and tested for temporal hydrologic effects on habitat variation of substrate particle size, water depth and water velocity by reducing data into principal component axes that were tested for differences among years with ANOVAs. We then tested for effects of habitat and hydrology variation on fish assemblages with canonical correspondence analysis. These analyses showed significant relationships between hydrologic variation and local habitats, and hydrology and habitat variables had significant relationships with fish assemblage structure. Our Mantel tests resulted in significant concordance among hydrology, local habitat variation and fish assemblage structure, suggesting associations of these variables. These results supported strong connections for hydraulic control over habitat variation and subsequent effects on fish assemblages. Copyright © 2011 John Wiley & Sons, Ltd.     

Flow and water temperature simulation for habitat restoration in the Shasta River,California

Low instream flows and high water temperatures are two factors limiting survival of native salmon in California's Shasta River. This study examines the potential to improve fish habitat conditions by better managing water quantity and quality using flow and water temperature simulation to evaluate potential restoration alternatives. This analysis provides a reasonable estimate of current and potential flows and temperatures for a representative dry year (2001) in the Shasta River, California. Results suggest restoring and protecting cool spring‐fed sources provides the most benefit for native salmon species from a broad range of restoration alternatives. Implementing a combination of restoration alternatives further improves instream habitat. Results also indicate that substituting higher quality water can sometimes benefit native species without increasing environmental water allocations. This study shows the importance of focusing on the limitations of specific river systems, rather than systematically increasing instream flow as a one size fits all restoration approach. Copyright © 2009 John Wiley & Sons, Ltd.     

EVALUATING STATISTICAL APPROACHES TO QUANTIFYING JUVENILE CHINOOK SALMON HABITAT IN A REGULATED CALIFORNIA RIVER

Decisions on managed flow releases in regulated rivers should be informed by the best available science. To do this, resource managers require adequate information regarding the tradeoffs between alternative methodologies. In this study, we quantitatively compare two competing multivariate habitat models for juvenile Chinook salmon (Oncorhynchus tschawytscha), a highly valued fish species under serious decline in a large extent of its range. We conducted large‐scale snorkel surveys in the American River, California, to obtain a common dataset for model parameterization. We built one habitat model using Akaike Information Criterion analysis and model averaging, ‘model G’, and a second model by using a standard method of aggregating univariate habitat models, ‘model A’. We calculated Cohen's kappa, percent correctly classified, sensitivity, specificity and the area under a receiver operator characteristic to compare the ability of each model to predict juvenile salmon presence and absence. We compared the predicted useable habitat of each model at nine simulated river discharges where usable habitat is equal to the product of a spatial area and the probability of habitat occupancy at that location. Generally, model G maintained greater predictive accuracy with a difference within 10% across the diagnostic statistics. Two key distinctions between models were that model G predicted 17.2% less useable habitat across simulated flows and had 5% fewer false positive classifications than model A. In contrast, model A had a tendency to over predict habitat occupancy and under predict model uncertainty. The largest discrepancy between model predictions occurred at the lowest flows simulated and in the habitats most likely to be occupied by juvenile salmon. This study supports the utility and quantitative framework of Akaike Information Criterion analysis and model averaging in developing habitat models. Copyright © 2012 John Wiley & Sons, Ltd.     

LANDSCAPE‐LEVEL MODEL TO PREDICT SPAWNING HABITAT FOR LOWER COLUMBIA RIVER FALL CHINOOK SALMON (ONCORHYNCHUS TSHAWYTSCHA)

We developed an intrinsic potential (IP) model to estimate the potential of streams to provide habitat for spawning fall Chinook salmon (Oncorhynchus tshawytscha) in the Lower Columbia River evolutionarily significant unit. This evolutionarily significant unit is a threatened species, and both fish abundance and distribution are reduced from historical levels. The IP model focuses on geomorphic conditions that lead to the development of a habitat that fish use and includes three geomorphic channel parameters: confinement, width and gradient. We found that the amount of potential habitat for each population does not correlate with current, depressed, total population abundance. However, reaches currently used by spawners have high IP, and IP model results correlate well with results from the complex Ecosystem Diagnosis and Treatment model. A disproportionately large amount of habitat with the best potential is currently inaccessible to fish because of anthropogenic barriers. Sensitivity analyses indicate that uncertainty in the relationship between channel width and habitat suitability has the largest influence on model results and that model form influences model results more for some populations than for others. Published in 2011 by John Wiley & Sons, Ltd.     

DIEL DIFFERENCES IN 0+ FISH SAMPLES: EFFECT OF RIVER SIZE AND HABITAT

Studies of diel patterns in 0+ fish assemblages in rivers are scarce and produce contradictory results. We compared day and night electrofishing samples at 29 sites on rivers of different sizes in the Czech Republic. Diel patterns of 0+ fish differed among sites, but were consistent within each river stretch. River size was negatively correlated with both the day : night ratio of abundance (day samples produced more 0+ fish in smaller streams, night samples produced more 0+ fish in larger rivers) and similarity between day and night assemblage. A higher day : night ratio of abundance and lower similarity between day and night samples were observed at shelter‐lacking habitats (beach) compared with shelter‐providing habitats (boulder bank and flooded terrestrial vegetation). Differences in 0+ fish size were not dependant on diel period, river size, habitat or species. Day‐only or night‐only samples provided only two‐third of the information provided by a combination of day and night samples. The effect of habitat type and river size on diel differences in electrofishing catches should be considered when deciding on 0+ fish sampling protocol. Copyright © 2011 John Wiley & Sons, Ltd.     

DISTRIBUTION AND HABITAT USE OF THE MISSOURI RIVER AND LOWER YELLOWSTONE RIVER BENTHIC FISHES FROM 1996 TO 1998: A BASELINE FOR FISH COMMUNITY RECOVERY

Past and present Missouri River management practices have resulted in native fishes being identified as in jeopardy. In 1995, the Missouri River Benthic Fishes Study was initiated to provide improved information on Missouri River fish populations and how alterations might affect them. The study produced a baseline against which to evaluate future changes in Missouri River operating criteria. The objective was to evaluate population structure and habitat use of benthic fishes along the entire mainstem Missouri River, exclusive of reservoirs. Here we use the data from this study to provide a recent‐past baseline for on‐going Missouri River fish population monitoring programmes along with a more powerful method for analysing data containing large percentages of zero values. This is carried out by describing the distribution and habitat use of 21 species of Missouri River benthic fishes based on catch‐per‐unit area data from multiple gears. We employ a Bayesian zero‐inflated Poisson model expanded to include continuous measures of habitat quality (i.e. substrate composition, depth, velocity, temperature, turbidity and conductivity). Along with presenting the method, we provide a relatively complete picture of the Missouri River benthic fish community and the relationship between their relative population numbers and habitat conditions. We demonstrate that our single model provides all the information that is often obtained by a myriad of analytical techniques. An important advantage of the present approach is reliable inference for patterns of relative abundance using multiple gears without using gear efficiencies. Copyright © 2011 John Wiley & Sons, Ltd.     

SPATIAL VARIABILITY IN SPAWNING HABITAT SELECTION BY CHINOOK SALMON (ONCORHYNCHUS TSHAWYTSCHA) IN A WILDERNESS RIVER

Chinook salmon (Oncorhynchus tshawytscha) survival during early life stages depends largely on spawning habitat selection by adults, which has been linked to biophysical stream variables (e.g. stream flow, velocity and substrate composition) as well as hyporheic exchange associated with riffle/pool and run/pool transitions. To examine how physical habitat variables influenced spawning habitat choice in one central Idaho (USA) wilderness stream, we used remote sensing techniques to classify and quantify the total amount of each aquatic habitat type present to assess how habitat quantity changed as stream order increased. Additionally, we measured physical habitat variables at each redd throughout the entire stream length for one spawning season to assess whether Chinook salmon selected for the same habitat parameters at varying spatial scales. Run, riffle and pool habitat types contributed similar proportions to the total area in both the upper and lower basins. However, ‘transitional zones’ (i.e. pool‐riffle and pool‐run transitions) accounted for 16% of the total area in the upper basin and only 4% in the lower. Redds were built in multiple habitat types in each of the three primary spawning locations, but transitional zones were chosen most frequently only in the upper basin. Significant differences in habitat variables were seen between spawning groups, with stream wetted width and velocity accounting for the majority of the variation. The techniques described here could be used to locate features that serve as indicators of potential spawning habitat, although caution should be exercised when extrapolating spawning habitat needs over large spatial extents. Copyright © 2013 John Wiley & Sons, Ltd.     

Instream flow methods: a comparison of approaches

Minimum flows in rivers and streams aim to provide a certain level of protection for the aquatic environment. The level of protection is described by a measure such as a prescribed proportion of historic flows, wetted perimeter or suitable habitat. Conflicting minimum flow assessments from different instream flow methods are arguably the result of different environmental goals and levels of protection. The goals, the way in which levels of protection are specified, and the relationship between levels of protection and the aquatic environment are examined for three major categories of flow assessment methods: historic flow, hydraulic geometry and habitat. Basic conceptual differences are identified. Flow assessments by historic flow and hydraulic methods are related to river size and tend to retain the ‘character’ of a river. Habitat-based methods make no a priori assumptions about the natural state of the river and flow assessments are based primarily on water depth and velocity requirements. Flow and hydraulic methods assume that lower than natural flows will degrade the stream ecosystem, whereas habitat methods accept the possibility that aspects of the natural ecosystem can be enhanced by other than naturally occurring flows. Application of hydraulic and habitat methods suggests that the environmental response to flow is not linear; the relative change in width and habitat with flow is greater for small rivers than for large. Small rivers are more ‘at risk’ than large rivers and require a higher proportion of the average flow to maintain similar levels of environmental protection. Habitat methods are focused on target species or specific instream uses, and are useful where there are clear management objectives and an understanding of ecosystem requirements. Flow and hydraulic methods are useful in cases where there is a poor understanding of the ecosystem or where a high level of protection for an existing ecosystem is required. © 1997 John Wiley & Sons, Ltd.     

Effects of Environmental Water Transfers on Stream Temperatures

Low streamflows and warm stream temperatures currently limit habitat and productivity of trout, including native Lahontan cutthroat trout in Nevada's Walker Basin. Environmental water transfers, which market water from willing sellers to instream uses, are evaluated to improve instream habitat. We use River Modelling System, an hourly, one‐dimensional hydrodynamic and water quality model, to estimate current and potential environmental water transfer effects on stream temperatures. Model runs simulate a range of environmental water transfers, from 0.14 to 1.41 cms, at diversions and reservoirs for wet year 2011 and dry year 2012. Results indicate that critically warm stream temperatures generally coincide with low flows, and thermal refugia exist in East Walker River, a tributary of the Walker River. Environmental water transfers reduce maximum stream temperatures by up to 3 °C in dry years and are more effective in dry years than wet years. This research suggests that environmental water transfers can enhance instream habitat by improving water quality as well as increasing instream flow. Copyright © 2015 John Wiley & Sons, Ltd.     

MODELLING THE EFFECTS OF RIVER FLOW ON POPULATION DYNAMICS OF PIPING PLOVERS (CHARADRIUS MELODUS) AND LEAST TERNS (STERNULA ANTILLARUM) NESTING ON THE MISSOURI RIVER

Reservoir management on the Missouri River has changed the flow regime that once created dynamic emergent sandbar habitat (ESH) for the interior least tern (Sternula antillarum) and piping plover (Charadrius melodus). High flows that create large amounts of ESH are now rare, but the remaining interannual variability in river stage has strong effects on the amount of ESH available for nesting shorebirds. The scarcity of habitat has led the United States Army Corps of Engineers to develop an adaptive management plan for the restoration of ESH to support nesting terns and plovers. We describe the stochastic simulation models of ESH, plover populations and tern populations used in the adaptive management process, and examine the effects of river flow on projected outcomes of habitat restoration. The population models are most sensitive to uncertainty in adult survival rates. Model validation against historical amounts of ESH and population sizes suggests the model is a reasonable predictor of future dynamics. Flow variability contributes as much uncertainty as parameter estimation error to plover model projections but negligible uncertainty to the tern model. Autocorrelation in flow between years has stronger effects on population outcomes than the intensity of habitat restoration effort does. We compared population outcomes after a habitat‐creating flow with population outcomes following habitat restoration and found that large pulses of habitat creation produced similar or better outcomes in the short term than low but consistent habitat restoration. However, bird populations fared better in the long term with low levels of restoration when habitat‐forming flows were rare. Copyright © 2013 John Wiley & Sons, Ltd.     

A STREAM EVOLUTION MODEL INTEGRATING HABITAT AND ECOSYSTEM BENEFITS

For decades, Channel Evolution Models have provided useful templates for understanding morphological responses to disturbance associated with lowering base level, channelization or alterations to the flow and/or sediment regimes. In this paper, two well‐established Channel Evolution Models are revisited and updated in light of recent research and practical experience. The proposed Stream Evolution Model includes a precursor stage, which recognizes that streams may naturally be multi‐threaded prior to disturbance, and represents stream evolution as a cyclical, rather than linear, phenomenon, recognizing an evolutionary cycle within which streams advance through the common sequence, skip some stages entirely, recover to a previous stage or even repeat parts of the evolutionary cycle. The hydrologic, hydraulic, morphological and vegetative attributes of the stream during each evolutionary stage provide varying ranges and qualities of habitat and ecosystem benefits. The authors' personal experience was combined with information gleaned from recent literature to construct a fluvial habitat scoring scheme that distinguishes the relative, and substantial differences in, ecological values of different evolutionary stages. Consideration of the links between stream evolution and ecosystem services leads to improved understanding of the ecological status of contemporary, managed rivers compared with their historical, unmanaged counterparts. The potential utility of the Stream Evolution Model, with its interpretation of habitat and ecosystem benefits includes improved river management decision making with respect to future capital investment not only in aquatic, riparian and floodplain conservation and restoration but also in interventions intended to promote species recovery. Copyright © 2012 John Wiley & Sons, Ltd.     

HYDROGEOMORPHIC CLASSIFICATION OF WASHINGTON STATE RIVERS TO SUPPORT EMERGING ENVIRONMENTAL FLOW MANAGEMENT STRATEGIES

As demand for fresh water increases in tandem with human population growth and a changing climate, the need to understand the ecological tradeoffs of flow regulation gains greater importance. Environmental classification is a first step towards quantifying these tradeoffs by creating the framework necessary for analysing the effects of flow variability on riverine biota. Our study presents a spatially explicit hydrogeomorphic classification of streams and rivers in Washington State, USA and investigates how projected climate change is likely to affect flow regimes in the future. We calculated 99 hydrologic metrics from 15 years of continuous daily discharge data for 64 gauges with negligible upstream impact, which were entered into a Bayesian mixture model to classify flow regimes into seven major classes described by their dominant flow source as follows: groundwater (GW), rainfall (RF), rain‐with‐snow (RS), snow‐and‐rain (SandR), snow‐with‐rain (SR), snowmelt (SM) and ultra‐snowmelt (US). The largest class sizes were represented by the transitional RS and SandR classes (14 and 12 gauges, respectively), which are ubiquitous in temperate, mountainous landscapes found in Washington. We used a recursive partitioning algorithm and random forests to predict flow class based on a suite of environmental and climate variables. Overall classification success was 75%, and the model was used to predict normative flow classes at the reach scale for the entire state. Application of future climate change scenarios to the model inputs indicated shifts of varying magnitude from snow‐dominated to rain‐dominated flow classes. Lastly, a geomorphic classification was developed using a digital elevation model (DEM) and climatic data to assign stream segments as either dominantly able or unable to migrate, which was cross‐tabulated with the flow types to produce a 14‐tier hydrogeomorphic classification. The hydrogeomorphic classification provides a framework upon which empirical flow alteration–ecological response relationships can subsequently be developed using ecological information collected throughout the region. Copyright © 2011 John Wiley & Sons, Ltd.     

A collaborative and adaptive process for developing environmental flow recommendations

Many river restoration projects are focusing on restoring environmental flow regimes to improve ecosystem health in rivers that have been developed for water supply, hydropower generation, flood control, navigation, and other purposes. In efforts to prevent future ecological damage, water supply planners in some parts of the world are beginning to address the water needs of river ecosystems proactively by reserving some portion of river flows for ecosystem support. These restorative and protective actions require development of scientifically credible estimates of environmental flow needs. This paper describes an adaptive, inter‐disciplinary, science‐based process for developing environmental flow recommendations. It has been designed for use in a variety of water management activities, including flow restoration projects, and can be tailored according to available time and resources for determining environmental flow needs. The five‐step process includes: (1) an orientation meeting; (2) a literature review and summary of existing knowledge about flow‐dependent biota and ecological processes of concern; (3) a workshop to develop ecological objectives and initial flow recommendations, and identify key information gaps; (4) implementation of the flow recommendations on a trial basis to test hypotheses and reduce uncertainties; and (5) monitoring system response and conducting further research as warranted. A range of recommended flows are developed for the low flows in each month, high flow pulses throughout the year, and floods with targeted inter‐annual frequencies. We describe an application of this process to the Savannah River, in which the resultant flow recommendations were incorporated into a comprehensive river basin planning process conducted by the Corps of Engineers, and used to initiate the adaptive management of Thurmond Dam. Copyright © 2006 John Wiley & Sons, Ltd.     

TIMING OF REDD CONSTRUCTION BY FALL CHINOOK SALMON IN THE HANFORD REACH OF THE COLUMBIA RIVER

Spawning habits of fall Chinook salmon in the Hanford Reach of the Columbia River have been documented with annual aerial surveys since 1948. We developed a series of models analysing these data, exploring the influence of environmental factors on the timing of redd construction. These models included a logistic regression and a dynamic modelling approach, with combinations of day of year (as a surrogate for environmental cues such as day length), water temperature and discharge as potential explanatory factors. Results of these analyses indicate that day of year was the strongest predictor of the timing of redd construction, but with significant modifying effects of water temperature and discharge. The dynamic modelling approach provides substantial advantages over a traditional logistic regression, including (1) the ability to treat data collected at non‐synchronous time intervals in a consistent fashion and (2) the ability to easily implement complex functions (e.g., threshold responses) relating behaviour to environmental cues. Evaluation of the series as a whole indicates that the median date of redd construction has increased over time, from approximately day 299 in 1950 to day 307 in 2010, as has the temperature on Oct 1 (16.3 °C–18.1 °C). The degree to which these changes are caused by climate change or dam operations is uncertain, however. Copyright © 2013 John Wiley & Sons, Ltd.     

Flavia Rocha Loures and Alistair Rieu-Clarke (eds), The UN Watercourses Convention in force: strengthening international law for transboundary water management

Abstract

The MODSIM 8.0 decision support system (DSS) for integrated river basin management (IRBM) has been adapted from a prior appropriation rights-based system to one found in Korea and in much of Asia where water deficits are shared among water use sectors, taking into account priorities established by water policy and institutional frameworks. The Korean version called KModSim is applied to the Geum River basin for evaluation of long-term sustainability of existing and new water infrastructure and facilities under integrated, basin-wide water resources management. KModSim is calibrated to the physical and hydrologic characteristics of the basin, as well as to operational and administrative water allocation policies for municipal and industrial water supply, irrigation, hydropower, transbasin diversions, and low-flow augmentation for environmental purposes. Conditional reservoir operational rules that adapt to changing river basin hydrologic conditions are developed from an implicit stochastic optimization algorithm and incorporated using the extensive user-customization capabilities of KModSim. Results demonstrate that decision guidance under KModSim enhances beneficial water uses in the Geum River system through fully integrated, basin-wide management.     

水电生态实践——分层取水结构

作为水电生态实践的重要组成部分之一,分层取水结构在水电开发程度高的国家很受青睐。以美国分层取水现状为基础,介绍了美国沙斯塔和饿马两个大型水电工程进水口的改建设计和运行效果,以及格兰峡水电站进水口改建的设计思想和存在的问题。分析美国水电开发以及运行中的经验、教训,建议我国水电生态工程建设要重视基础研究,论证要关注各利益相关群体,设计要体现水电生态工程的循序性、特殊性和前瞻性。     

Spatially variable effects of streamflow on water temperature and thermal sensitivity within a salmon-bearing watershed in interior British Columbia,Canada

Warming temperatures can have negative consequences for aquatic organisms, especially cold-adapted fishes such as Pacific salmon. The magnitude of warming is related to the thermal sensitivity of streams in salmon-bearing watersheds (i.e., change in stream temperature for every 1°C increase in air temperature), which can vary based on several factors including streamflow. Management actions to increase streamflow may therefore benefit salmon by decreasing thermal sensitivity. However, the effects of streamflow on thermal sensitivity are often complex, as the temperature of flow inputs can directly increase or decrease temperatures. This study aimed to disentangle the influence of streamflow on thermal sensitivity and stream temperature over 4 years in the Nicola River, a regulated semiarid watershed in south-central British Columbia, Canada. A statistical modeling approach was used to estimate streamflow effects on stream temperatures and thermal sensitivity (i.e., relationship of regional air temperature to stream temperature) at 12 sites from 2018 to 2021. Streamflow had a variable influence on stream temperatures across the watershed via both direct effects and by modulating thermal sensitivity. At a given site, streamflow was generally negatively associated with summer daily mean stream temperature, but the magnitude of its influence varied among locations and years. The influence of streamflow on thermal sensitivity was also highly variable both spatially and temporally. The analysis suggests that there may be complex relationships between streamflow, stream temperature, and thermal sensitivity, which complicates the efficacy of flow as a lever to mitigate high temperatures in regulated systems.     

Development of transient habitat modeling for stream Macrozoobenthos

In addition to the hydromorphological pressure on the ecological conditions of free-flowing river courses, increasing water temperature is affecting the water bodies, particularly by changing freshwater community compositions. The low discharge of numerous European rivers in the dry and hot hydrological year 2022 proves this relevance. Therefore, ecological assessment tools such as habitat modeling should take these factors into account when assessing the quantity and quality of habitats. In this paper, the habitat modeling tool “Transient River Habitat Modeling for Macrozoobenthos” (TRiMM) is improved by incorporating a fuzzy logic approach and adding water temperature to the set of parameters determining habitat suitability for macrozoobenthos. Habitat-relevant parameters, including hydromorphological factors (depth, velocity, mineral and organic substrate) and a water quality factor (temperature), are combined in the habitat model so that it can more broadly characterize river physical conditions and their interactions with biological indicators. Habitat modeling employed the mentioned parameters to simulate suitability for the macrozoobenthos in a small river in central Saxony, Germany. Due to its deteriorated condition, this river was selected as a representative for thousands of kilometers of small rivers across the region, which have been restored. The model simulated the status quo of river conditions from spring to summer for three macrozoobenthos species (Ancylus fluviatilis, Ephemera danica and Gammarus fossarum). The results showed that the natural flow resulted in dynamic habitat suitability both spatially and temporally, which differs for each species. Remarkably, the five-parameter model (depth, velocity, temperature, mineral, and organic substrate) generally performed better compared to a similar model without temperature.