Instream Flow Incremental Methodology Research Articles

An improved 3D fish habitat assessment model based on the graph theory algorithm

With the economic development, social progress and the increase in power demand, the number of water conservancy projects has gradually increased. However, the reservoir dams inevitably lead to changes in the river connectivity and hydraulic characteristics of rivers, causing damage to fish habitats. Regulating the operation of dams to supplement the ecological flow required by fish is usually an effective way to protect river fish habitats. Based on the graph theory algorithm, we proposed an improved three-dimensional habitat model that comprehensively considered the quantity and quality of fish habitat and used it to the effect assessment of water conservancy project construction on fish habitat. The fish habitat quality evaluation indicators in this paper mainly emphasized the pivotal role of core habitat patches and the connectivity between habitat patches, namely, habitat importance index (HII) and habitat connectivity index (HCI). Then, the model was combined with the Instream Flow Incremental Methodology (IFIM) and applied to the habitat assessment of Schizothorax prenanti (S. prenanti) in the Anshunchang reach of the Dadu River. The results showed that the change trend of the habitat index curves of different water depths showed a trend of first increasing and then decreasing, but the inflection points of the curves and the habitat indexes of different water depths were different. Taking into account the bottom living habits of target fish, the most suitable flow range for S. prenanti was from 271.7 m3/s to 489.1 m3/s. Compared with previous studies, the improved three-dimensional habitat model effectively avoids simulation errors caused by ignoring habitat quality and differences in fish habits.

A CUDA Fortran GPU-parallelised hydrodynamic tool for high-resolution and long-term eco-hydraulic modelling

Eco-hydraulic models are wide extended tools to assess physical habitat suitability on aquatic environments. Currently, the application of these tools is limited to short river stretches and steady flow simulations. However, this limitation can be overcome with the application of a high-performance computing technique: graphics processing unit (GPU) computing. R-Iber is a GPU-based hydrodynamic code parallelised in CUDA Fortran that, with the integration of a biological module, performs as an eco-hydraulic numerical tool. R-Iber was validated and applied to real cases by using an optimised instream flow incremental methodology in long river reaches and long-term simulations. R-Iber reduces the computation time considerably, reaching speed-ups of two orders of magnitude compared to traditional computing. R-Iber allows for overcoming the current limitations of the eco-hydraulic tools with the simulation of high-resolution numerical models calculated in a reasonable computation timeframe, which provides a better representation of the hydrodynamics and the physical habitat.

Evaluation of the impact of urban river bends on the enhancement of aquatic habitats using a two-dimensional habitat suitability model

The complex hydro-morphology of river bends plays an important role for creating and maintaining diverse habitat conditions for aquatic organisms. In this study,a dedicated standalone piece of software for benthic habitat simulation, which couples a two-dimensional (2D) depth-averaged water–sediment mathematical model with an instream flow incremental methodology, was devised to quantitatively evaluate the impact of channel bends on enhancing aquatic habitats. The multi-species integrated suitability index (CSI) curves based on three ecological variables were obtained. The test site was a 1.7-km-long stretch of the Jin Jiang River, which is a tributary of the Min Jiang River that flows through Huayang Town in Chengdu City, China. The potential value of aquatic habitats was quantitatively evaluated using the weighted usable area (WUA). The predicted WUA in the bend reach was 10.2%–16.6% greater than that in the straight reach. Moreover, the mean WUA decline rate was ~7.2% in the straight reach and ~5.6% in the bend reach. With increase in discharge, the WUA decreased more slowly in the bend reach compared to the straight reach. Our study indicates that for improving the aquatic habitats in urban rivers, the channel bends are beneficial. Compared with straight reaches, they not only could improve the availability of aquatic habitats but could also reduce the negative impact of the changes of discharge on the habitat. To summarize, this study provides a specific reference for ecological restoration.

PHABSIM/SEFA Application for Minimum Flows and Levels Development in Florida

Physical Habitat Simulation System (PHABSIM) or System for Environmental Flow Analysis (SEFA) are typically used to simulate the relationship between river flow and physical habitat of various life stages of a fish species. They are a component of the Instream Flow Incremental Methodology (IFIM) and are widely used across the globe for deductive estimation of biological effects of stream flow alteration. These models have been applied at various spatial and temporal scales corresponding to the objectives of the specific applications. The objectives of this work effort are to review spatial and temporal scales of previous habitat modelling applications and to recommend a best practice approach for the application of physical habitat simulation software. Two leading software packages are considered-PHABSIM and SEFA, both are improvements of IFIM framework. Specifically, this research paper recommends best practices that can be used in environmental flows development. The review was focused on literature related to selecting species, and the time steps for developing and applying Area Weighted Suitability (AWS) vs. discharge curves used for developing environmental flows. The term AWS in SEFA replaces the original weighted usable area (WUA) in PHABSIM because it is a more accurate description of the physical meaning of the variable.

Relationship between Morphological Characteristics and Quality of Aquatic Habitat in Mountain Streams of Slovakia

This study evaluated the relationship between abiotic flow characteristics and habitat quality. Habitat quality was assessed using the Instream Flow Incremental Methodology (IFIM), which uses bioindication. Brown trout was selected as a bioindicator because of its sensitivity to morphological changes and its occurrence in sufficient reference reaches. The correlation between the morphological characteristics of the stream and the area-weighted suitability (AWS), which represents habitat quality, was evaluated. Fifty-nine reference reaches of fifty-two mountain and piedmont streams in Slovakia were analysed. The correlation analysis demonstrated the strongest relationship between the AWS and the stream depth and width. The relationship between the water surface area and the AWS indicated that, for mountain streams, there is a significantly increasing trend of the AWS value with increasing surface area. Considering piedmont streams, the AWS variation with a change in the water-surface area was minimal. These results can form the basis for deriving regression equations to determine habitat quality. Such a procedure can significantly simplify the evaluation of the quality of aquatic habitat, making it much more accessible for design practice.

Evaluation of impact of spur dike designs on enhancement of aquatic habitats in urban streams using 2D habitat numerical simulations

Although channelized urban streams provide aesthetic and economic value, they reduce biodiversity and alter the habitats of aquatic organisms. Spur dikes not only prevent the erosion of riverbanks, but also generally improve aquatic habitats. River 2D is widely used to analyze the aquatic habitats. However, the model often faces a challenge of lacking sediment and riverbed evolution module, which is difficult to predict the change of aquatic habitats. In this study, a depth-averaged habitat model, which couples a two-dimensional water-sediment shallow water model with an Instream Flow Incremental Methodology (IFIM), was provided to evaluate the impact of spur dikes on the improvement of aquatic habitats in the Jinjiang Stream in Chengdu, China.The potential value of aquatic habitats was quantitatively evaluated by a weighted useable area (WUA). Under different spur dike scenarios, the WUA is greater than under natural conditions, that is, the construction of spur dikes is beneficial for improving the habitat of aquatic organisms in urban rivers. In addition, further analysis from the simulation results shows that the three-spur dike scenario with a flow of 40 m³/s represents the best layout of spur dikes. Our study indicates that adjusting the spur dike layout is an effective instrument to enhance aquatic habitats, and can provide a certain reference for water ecological restoration and river management.

Application of a New Species‐Richness Based Flow Ecology Framework for Assessing Flow Reduction Effects on Aquatic Communities

AbstractWater‐resources managers are challenged with maintaining a balance among beneficial uses throughout river networks and need robust means of assessing potential risks to aquatic life resulting from flow alterations. This study generated ecological limit functions from species‐streamflow relations to quantify potential fish richness response to flow alteration and compared results to currently accepted streamflow management guidelines. Modeled responses of absolute richness change were watershed specific and varied among sample sets derived from hydrologic unit classifications of different sizes (large HUC 6 basins to regional scale HUC 8). With a 20% flow reduction, 10% of HUC 8 predicted a richness decrease in one or more taxa. While absolute richness change was consistent across streams within a HUC, percent richness change was stream size dependent. Comparisons with Instream Flow Incremental Methodology habitat models predicted habitat loss greater than percent richness change; however, predictions for habitat and richness decreased similarly as stream size decreased. Watershed‐specific responses from flow reductions could allow water‐resources management decisions to be made locally based on the predicted richness change for certain sized streams. Quantitative results highlight the utility of a richness‐based framework for generating watershed‐specific risk assessments that validate and inform currently employed water‐resources management practices.

Effect of Probability Distribution-Based Physical Habitat Suitability Index on Environmental-Flow Estimation

Habitat suitability index (HSI) is a fundamental factor in ecological river-restoration projects for assessing fish habitat to create inhabited environment for aquatic organisms. An accurate estimation of HSI requires long-term-monitored data including flow velocity, water depth, and bed materials; however, this is not easy to collect, and the dataset comprises local characteristics. Therefore, it is difficult to present a generalized method of HSI estimation with limited local and temporal data. In this study, the probability distribution was applied for HSI estimation with limited data measured in the tributaries of Han and Geum Rivers in South Korea. Log-normal distributions were applied to the water depth and velocity data of aquatic habitat for Zacco platypus, and then the developed log-normal distributions were used as the HSI. The HSIs developed by applying the log-normal distribution were compared with the HSIs developed using the instream flow and aquatic system group (IFASG) method. By using the log-normal-distribution-based HSIs, the environmental flows estimated through the physical-habitat-assessment models based on instream flow incremental methodology were also compared with the IFASG-based results. The environmental flows were determined to be similar within an optimal range in both cases of the tributaries of Han and Geum Rivers.

Indigenous Rights and Climate Change: The Influence of Climate Change on the Quantification of Reserved Instream Water Rights for American Indian Tribes

The people indigenous to the Western portion of the lands now referred to as North America have relied on aquatic species for physical, cultural, and spiritual sustenance for millenia. Such indigenous peoples, referred to in the American legal system as Indian tribes, are entitled to water rights for fish habitat pursuant to the Winters Doctrine, which holds that the federal government impliedly reserved water rights for tribes when reservations were created. Recently, the methodology for quantifying these rights has been the Instream Flow Incremental Methodology (IFIM) and/or one of its major components, the Physical Habitat Simulation Model (PHABSIM). These models result in water right claims for fixed quantities of water, which—although not required by law—result in instream water rights that are decreed without any means for adjustment to account for changing conditions. Ultimately, climate change will likely alter the amount of water necessary to protect aquatic habitat, rendering obsolete any water right that is based on a fixed quantity. As climate change continues to worsen, we argue that quantifying reserved water rights for inflexible fixed quantities imposes an unreasonable burden on American Indian tribes. Instead, we suggest the application of a number of integrated technical and legal solutions to mitigate the uncertainty Indian tribes currently face from climate change as they seek to protect their rights, resources, and homelands.

Assessment of the River Habitat Quality Using Bioindication in the Piedmont Stream Handlovka in Slovakia

The paper focuses on an assessment of a river habitat quality in piedmont streams using a bioindication by the brown trout. The study was performed at four sites, piedmont streams in Slovakia, but modelling procedure herein is particularly described only for the Handlovka River, in the Nitra basin. For the field and modelling work, a natural reference reach and a regulated reach have been chosen within each stream. Hydrometric, geodetic and morphological measurements were conducted. The paper focuses on modelling in the Hydrocheck software and Computer Software System for Environmental Flow Analysis (SEFA) based on the Instream Flow Incremental Methodology (IFIM) and result output is the Area Weighted Suitability (AWS). The abiotic parameters for modelling were chosen as depth and velocity rates. The biotic parameter was chosen as an ichthyologic abundance of the brown trout. The results show significant difference between natural and modified channel, presenting natural reach as more suitable for fish abundance with higher AWS score. The regulated reaches are significantly affected by the river regulation, construction of concrete panels and sever contamination from anthropogenic runoff. On the contrary, the natural channels offer enough morphological structure and various shelter possibilities for enhancement of fish population.

Application of Extended Habitat Suitability Curves for Depth in Nitrica River

This study assesses the impact of basic stream abiotic parameters on the quality of aquatic habitat and inserts them to the aquatic habitat quality assessment of the mountain and piedmont streams. The created methodology was applied on the Nitrica River. The study is based on the objectification and modification of parameters of habitat suitability curve for the depth. The habitat suitability curve is one of the many basic parts of the Instream Flow Incremental Methodology (IFIM). IFIM is the methodology where the quality of aquatic habitat is interpreted according to a bioindication. The bioindication is provided by ichthyofauna. For this study, the minnow (Phoxinus phoxinus) was chosen as a bioindicator. The main reason for selecting the minnow as a bioindicator was that there was a sufficient frequency during the ichthyologic survey on the studied river. The basic result from the field measurement is the habitat suitability curve for depth. This measured habitat suitability curve is not adequate to describe the aquatic habitat. The suitability curve derived from just one measurement does not take into account the fact that the increase in flow has not changed the quality of the habitat until the time when the fish starts to be flushed out of the environment. This is the reason why this scientific research was oriented on the modification of habitat suitability curve for a wider range of flow. The evaluation was done by the System of Environmental Flow Analysis (SEFA). SEFA is a new software that implements the substance of the IFIM. The modification of the habitat suitability curve is applied on the Nitrica River.

Law and Science Series No. 1: The Contemporary Methodology for Claiming Reserved Instream Flow Water Rights to Support Aquatic Habitat

This article is the first in a series to provide information related to commonly used technical methodologies in furtherance of legal rights held by American Indian Tribes. Specifically, this article discusses the method for estimating water rights necessary to protect instream habitat to support fish. Unlike reserved water rights for irrigation — which has the well settled practicably irrigable acreage (“PIA”) standard — the United States Supreme Court has not identified a single quantification methodology appropriate for traditional uses of water. Instead, lower courts have fashioned a more ad hoc approach to quantifying traditional reserved water rights. This seems preferable given that unlike irrigation water rights, which are fairly uniform in their nature, each tribe’s traditional uses of water are unique and driven by the physical, historical, and cultural factors present for each tribe. Although the method for quantifying these rights have evolved over time, courts have slowly converged on the Instream Flow Incremental Methodology (IFIM) and its component part, the Physical Habitat Simulation Model (“PHABSIM”). Although the IFIM/PHABSIM method does not enjoy the de jure recognition of its sister-methodology PIA, the consistent use and acceptance of this method have caused it to become the de facto method for quantifying reserved instream water rights to protect fish habitat. The purpose of this article is to provide an explanation of the IFIM/PHABSIM methodology in an effort to put practitioners in the position to apply and, where necessary, critique the method. It proceeds in a chronological fashion; describing from beginning to end the steps necessary to develop a reserved instream water right claim using the IFIM/PHABSIM method.

Analysis and restoration of an ecological flow regime during the Coreius guichenoti spawning period

The development of cascade hydropower in the Yalong River has changed the hydrological regime of the river and sharply reduced the Coreius guichenoti population dwelling downstream of the JinPing II power station. In this paper, an eco-hydrological index system for C. guichenoti habitat was constructed based on Indicators of Hydrologic Alteration (IHA) and Environment Flow Components (EFC), which aimed to coordinate the processes of ecological hydrological and water temperature variations to guarantee the oviposition of C. guichenoti. The analysis revealed that the suitable rise rate and fall rate intervals, which are dimensionless parameters, were 0.05–0.10 and 0.01–0.03, respectively, during the spawning period. The rise and fall durations were both 1–2 days, the cycle of water fluctuations was 3–5 days, the flow pulse duration was 5–7 days, the flow pulse rise rate was 0.56–0.65, and the flow pulse fall rate was 0.23–0.50. Then, the Instream Flow Incremental Methodology (IFIM) method was used to calculate the ecological base flow during the C. guichenoti spawning period. Moreover, the ecological flow regime for C. guichenoti downstream of the JinPing II power station during the spawning period was determined based on eco-hydrological indicators and water temperature requirements. These results showed that the ecological flow regime could not only guarantee oviposition but also meet the drifting conditions required for eggs, and therefore, the ecological operation of diversion-type hydropower stations and cascade hydropower stations needs to be given more attention to provide suitable spawning conditions in target fish habitats.

Physical habitat simulation for small-sized characid fish species from tropical rivers in Brazil

ABSTRACT Physical habitat simulation (PHABSIM) is an important step of the instream flow incremental methodology (IFIM), which is applied to establish environmental flow regimes. This study applied the PHABSIM in two reaches of the Velhas river basin, whose long-term discharges are similar but are under different degrees of impact. Suitability curves were obtained for fish species using traditional methods (Astyanax sp., Piabarchus stramineus, Piabina argentea and Serrapinnus heterodon) and generalized additive models for fish density (Astyanax sp., P. argentea and S. heterodon). The results of habitat use depended on the method for curves generation. Applying the suitability curves by traditional methods, different discharge scenarios were simulated. The flow increasing from a dry scenario to a discharge of 1 year of return promotes a possible habitat increase for all species. However, the same hydrological flow percentiles produce different habitat proportions in different rivers. This work demonstrates that regardless of how suitability curves for the Neotropical species are generated, caution should be taken when applying them. However, the PHABSIM method allows more complex analyses than the traditional approaches based on minimal flow estimations, which is usually applied in South America.

유량증분방법론에 의한 생태유량 산정 모형의 비교연구

유량증분방법론에 의한 생태유량 산정 모형의 비교연구

Influence of discharge on fish habitat suitability curves in mountain watercourses in IFIM methodology

Abstract In this study, the quality of the aquatic habitats of mountain and piedmont streams was evaluated using the ‘Instream Flow Incremental Methodology (IFIM)’ decision-making tool. The quality of habitats was interpreted from the behaviour of bioindicators in the form of habitat suitability curves (HSCs). From 1995 until the present, 59 different reaches of 43 mountain streams in Slovakia and 3 validation reaches were evaluated, and the results analysed. The aim of this study was to generalize the parameters of the HSCs for the brown trout. The generalized curves will be useful for water management planning. It is difficult and time-consuming to take hydrometrical and ichthyological measurements at different water levels. Therefore, we developed a methodology for modifying suitability curves based on an ichthyological survey during a low flow and a flow at which fish lose the ability to resist the flow velocity. The study provides the information how such curves can be modified for a wider flow range. In summary, this study shows that generalized HSCs provide representative data that can be used to support both the design of river restoration and the assessment of the impacts of the water use or of climate change on stream habitat quality.

Analysis of environmental flow requirements for macroinvertebrates in a creek affected by urban drainage (Prague metropolitan area, Czech Republic)

The habitat suitability index and environmental flow requirements were assessed for ten species of macroinvertebrates in a 2 km length section of the urban Botic creek (average flow 0.4 m3 s−1) in Prague. Botic creek has been affected by two combined sewer overflows (CSO). Spring, summer and fall seasonal environmental flow requirements were identified using the Physical HABitat SIMulation System (PHABSIM) approach for the whole macroinvertebrate community: Spring – optimal flow 0.32–0.38 m3 s−1, minimal flow 0.20–0.21 m3 s−1 and maximal acceptable flow 0.91–0.93 m3 s−1; Summer - optimal flow 0.42–0.45 m3 s−1, minimal flow 0.19–0.21 m3 s−1 and maximal acceptable flow 0.95–1.00 m3 s−1; Fall - optimal flow 0.38–0.48 m3 s−1, minimal flow 0.22–0.23 m3 s−1 and maximal acceptable flow 0.95–0.98 m3 s−1. The seasonal variability of environmental flow for all three categories is approximately 10%. Environmental flow requirements of the studied species and their life stages vary with depth, velocity and bottom substratum. Due to inflow from the CSOs, the optimal and maximal acceptable flow are not maintained and the maximal flow is exceeded by more than twice its value. Although the Instream Flow Incremental Methodology (IFIM) was primarily designed for large impounded rivers, the study proved its applicability in small streams affected by urbanization and urban drainage.

Consideraciones para la aplicación del método hidráulico R2CROSS para estimar caudales ecológicos en Colombia

Colombia es un país privilegiado en cuanto a la oferta hídrica, sin embargo la mayor parte de ésta, que se encuentra en zonas poco pobladas y la fracción de agua superficial, disponible para las áreas de mayor concentración poblacional, se ve afectada por la sobreexplotación y la contaminación de los ríos. Por esta razón, se sugiere la estimación del caudal ecológico como un instrumento para el manejo de las cuencas del país. Dentro de este trabajo de revisión bibliográfica se presentan los principales conceptos asociados al caudal ecológico, las diferentes metodologías utilizadas para su estimación y se analizan los antecedentes en Colombia. Posteriormente, se hace énfasis en el método hidráulico R2CROSS, se mencionan sus bases teóricas y se muestra el caso de estudio de los ríos Assabet y Charles en Massachusetts (Estado Unidos). A partir de allí, se hizo un comparativo con las condiciones locales para definir las ventajas y desventajas de la aplicación de este método en Colombia. Algunas de las ventajas identificadas fueron la relación costo-beneficio, el poco tiempo requerido para su aplicación, la obtención de resultados similares a los de métodos más complejos como el de la Instream Flow Incremental Methodology (IFIM) y la conveniencia para usarlo en lugares con información hidrológica incompleta. Por otro lado, dentro de sus desventajas se encuentra un mayor costo que los métodos hidrológicos, los sesgos derivados de suponer que a partir de los parámetros hidráulicos se pueden determinar las condiciones óptimas para todas las especies del ecosistema acuático y rivereño y finalmente, su precisión que depende de una correcta elección de la sección del río.

Ecohydraulics exemplifies the emerging “paradigm of the interdisciplines”

ABSTRACTThe basic premise underlying ecohydraulics is deceptively simple: create a new discipline focused on the effects of water movement in aquatic ecosystems by melding principles of aquatic ecology (including aspects of fluvial geomorphology) and engineering hydraulics. However, advancing ecohydraulics as a synthetic, organized field of study is challenging because hydraulic engineers and ecologists (1) study processes that differ substantially in spatial and/or temporal scale; (2) have very different approaches to modelling; (3) utilize different sets of mathematical formulations, concepts, and assumptions; and (4) address problems with vastly different patterns of complexity and uncertainty. The differences between engineering and ecology must be reconciled within a set of concepts and practices applicable to ecohydraulics. This reconciliation is essential if ecohydraulics is to achieve the scientific esteem of its parent disciplines. First, we review how the competing paradigms of determinism and empiricism structure engineering and ecology, respectively. We then derive two guiding principles that facilitate the integration of ecology and hydraulics, the single reference framework and the multiple reference framework guiding principles. Third, we provide illustrative examples of these principles using a simple hydraulic fish habitat analysis based on physical habitat simulation (PHABSIM) system of the instream flow incremental methodology (IFIM) and a detailed fish movement model using Eulerian–Lagrangian–Agent methods (ELAMs). Based on these examples, we develop insights and conclusions to guide further advances in ecohydraulics and, perhaps even serve as a template to aid development of other interdisciplinary fields.

전주천 상류부의 서식처 적합도 지수 및 생태유량 산정

In this study, WUA (Weighted Usable Area) based on the Instream Flow Incremental Methodology (IFIM) was calculated to determine ecological flow at JeonJu-Cheon by using River2D model. To calibrate River2D, simulation results for low flow conditions of River2D were compared with calibrated HEC-RAS simulation results and the optimum parameters were determined. The results were RMSE (0.18), NSE (0.71) and coefficient of determination (0.78) for velocity and RMSE (0.02), NSE (0.71), coefficient of determination (0.73) for water depth. The result shows that the model successfully simulates the water flows. A selected target fish species to build the habitat suitability index were composed of Zaccoplatypus and Coreoleuciscus splendidus. These species showed the highest occurrences over the past decade in f ish monitoring. Also, The WUA-Discharge curve was calculated with the suitability index in a medium flow conditions. From the result, WUA is changed according to flowrate. In the flowrate-WUA/A graph, ecological flow can be determined at 1.8~2.0 m/s for Zaccoplatypus 2.0 m/s and Coreoleuciscus splendidus 1.8 m/s at JeonJu-Cheon upstream. When compared with flow-duration analysis, it is demonstrative that simulation results fitted ecological flow considering quantity of available habitat for each fish species.