• Ecology and Resilient Infrastructure
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• v.2 no.4
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• pp.317-323
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• 2015

This study investigated the impact of the morphological change on a physical fish habitat in the downstream reach of a dam using long-term mobile bed simulation. The quasi-steady model was used for hydraulic simulation and the habitat suitability index model was applied for physical habitat simulation. For simulating long-term morphological change of the stream bed, The Exner equation was used. Sorting of bed material was also considered. The results of simulation showed that erosion and armoring process occurred in a reach downstream of the dam and change of physical habitat for Zacco platypus followed. These results indicate that channel morphology and substrate conditions effected the physical habitat for considering long-term investigation.

• Journal of Korean Society on Water Environment
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• v.31 no.1
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• pp.35-41
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• 2015

This study focuses on whether a physical habitat model, River2D, is useful to assess and design stream restoration. To achieve the aim, the habitat suitability for Zacco Platypus was analyzed using River2D at midstream of the Anyang-Cheon through modifying the low flow channel and changing the flow discharge. The River2D simulation results show that the inhabited environment for Zacco Platypus is improved by increasing the sinuosity of the low flow channel, and vice versa. Also the inhabited environment for Zacco Platypus gets worse when there is no additional flow for maintenance water supply at the stream flowing through cities. In this respect, the physical habitat simulation study based on the River2D model is useful because it provides a practical guidance in designing stream restoration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.805-812
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• 2014

This study investigates the impact of morphological change on the physical habitat simulation. For this, CCHE2D model is used for the hydraulic analysis including the morphological change, and the physical habitat suitability is assessed with habitat suitability curves. The model is applied to a 2.5km long reach downstream of the Goesan Dam, from Sujeon Bridge to Daesu Weir. Flow data of discharge and stage in July, 2006 are used in the computation. The numerical model is verified by means of comparison with the measured water surface elevation data, and the variation of the river bed is not verified in this study. Adult Zacco platypus is chosen for the dominant species. Physical habitat simulations result in composite habitat suitability and weighted usable area for drought, low, normal, and averaged-wet flows. The simulation results indicate that the composite suitability index increased at reaches right downstream of the Sujeon Bridge and around the bend. This also increased weighted usable area by 5.4-11.3%.

• Journal of Environmental Impact Assessment
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• v.21 no.5
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• pp.631-648
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• 2012

The integrative ecological approaches of chemical assessments, physical habitat modelling, and multi-metric biological health modelling were applied to Gwanpyeong Stream within Gap-Stream watersheds to evaluate environmental impacts on the constructions of residential and commercial complex. For the analysis, the surveys conducted from 45 sites of reference streams within the Gap-Stream watershed and 3 regular sites during 2009 - 2010. Physical habitat health, based on the habitat model of Qualitative Habitat Evaluation Index(QHEI) declined from the headwaters(good - fair condition) to the downstream(poor condition). Chemical water quality, based turbidity and electric conductivity(EC), was degraded toward to the downstream, and especially showed abrupt increases, compared to the values of control streams(CS). Also, concentrations of chlorophyll-a in the downstreams were greater compared to the control stream(CS), indicating an eutrophication. Biological health conditions, based on the Index of Biological Integrity(IBI) using fish assemblages, averaged 19.3 which is judged as a fair condition by the biological criteria of the Ministry of Environment, Korea. The comparisons of model metric values in sensitive species and riffle-benthic species on the Maximum Species Richness Line(MSRL) of 45 reference streams indicated a massive disturbances in all sampling locations. Also, tolerance guild and trophic guild analyses suggest that dominances of tolerant species and omnivores were evident, indicating a biological degradation by habitat disturbances and organic matter pollutions. There was no distinct longitudinal variations of IBI model values from the headwater to the downstream in spite of slight chemical and habitat health gradients among the sampling sites. Overall, integrative ecological health(IEH) scores, based on the chemical, physical, and biological parameters, were low compared to the 45 reference streams due to physical and chemical disturbances of massive constructions of the residential and commercial complex. This stream, thus showed a tendency of typical urban streams which are disturbed in the chemical water quality, habitat structures, and biological integrity. Effective stream management plans and restoration strategies are required in this urban stream for improving integrative stream health.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2B
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• pp.147-154
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• 2011

Physical habitat assessment models based on Instream Flow Incremental Methodology have been developed as a decision making tool to estimate appropriate discharge for environmental flow and water use management. These models, however, require extensive knowledge on various academic disciplines, complicated input data, and empirical data. We propose a Simplified Habitat (SIMHAB) simulation model for the estimation of physical structure of fish habitat and environmental flow at the planning stage. SIMHAB is applied to a river system for which physical and ecological data are available, and its applicability is investigated. Simulated results appeared to be similar to field survey data and those of such models as PHABSIM and River2D. However, SIMHAB requires much less input data. As such, the proposed model, SIMHAB can easily be applicable to river restoration projects including designing of physical habitat, estimation of environmental flow, and water resource management.

• Journal of Ecology and Environment
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• v.36 no.1
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• pp.73-83
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• 2013

The object of this study was to evaluate lotic ecosystem health using multiple eco-metric approaches such as water chemistry diagnosis, physical habitat health evaluations, and biological integrity modeling at 100 streams of four major watersheds. For the study, eight chemical water quality parameters such as nutrients (N, P) and organic material were measured and 11-metric models of Qualitative Habitat Evaluation Index (QHEI) and multiple eco-metric health assessment model (MEHA) were applied to the four major watershed. Nutrient analysis of nitrogen (N) and phosphorus (P) in all watersheds indicated a eutrophic state depending on the locations of sampling streams. Physical habitat health, based on the QHEI model, averaged 114 (range: 56 - 194), judging as a "good condition" by the criteria of Plafkin et al. (1989). In addition, primary (H1 - H4), secondary (H5 - H7), and tertiary habitat metric variables (H8 - H11) were analyzed in relation to the physical habitat degradations. The plots of tolerant species ($P_{TS}$) and sensitive species ($P_{SS}$) to water quality showed that the proportions of $P_{TS}$ had positive linear functions with nutrients, and that the $P_{SS}$ had inverse linear relations with the chemical variables. The model of eco-metric health assessment showed that mean MEHA was 20.4, indicating a fair condition. Overall, our data suggest that water chemistry, based on nutrients and organic matter, directly modified the trophic structures in relation to food chain in the aquatic ecosystems, and then these directly influenced the compositions of tolerance/sensitive species, resulting in degradations of overall ecological health.

• Ecology and Resilient Infrastructure
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• v.6 no.2
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• pp.101-108
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• 2019

This study investigated the impact of abandoned channel restoration on fish habitat using the physical habitat simulation. The study area is a 1.2 km long reach of the Cheongmi-cheon stream. In the study area, the restoration of the abandoned channel was carried out from July 2012 to December 2105. Physical habitat simulations were carried out for both cases before and after the restoration. The River2D model and habitat suitability curve were used for hydraulic and habitat simulations, respectively. Zacco platypus, which is a dominant fish species in the study area, was selected as target fish for the physical habitat simulation. Hydraulic simulations were carried out before and after restoration for various discharges. Then, composite suitability index and weighted usable area were calculated before and after restoration and changes in the physical habitat of Zacco platypus were discussed. Simulation results indicated that the abandoned channel restoration is effective in creating fish habitat and mitigating the degradation of fish habitat from the high flow condition.

• Journal of Korea Water Resources Association
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• v.40 no.11
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• pp.909-920
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• 2007

River restoration and environmental improvement projects have been peformed by social needs, therefore methodology for evaluating such projects must be provided. The PHysical HABitat SIMulation system (PHABSIM) is proposed as a tool for the assessment of hydraulic habitat suitability for aquatic species related to flow regime in river. This study evaluates the change of physical habitat for Zacco platypus according to small dam removal and the model suitability by applying PHABSIM to the reach where small dam was removed. It is shown that the physical habitat is generally increased and improved where the small dam was removed. However, physical habitat in the spawning stage that has a weak swimming speed is decreased by increased flow velocity in the upstream area of small dam, so proper countermeasure for that condition should be needed. Consequently, PHABSIM can be effectively used to provide methodology for assessment and necessity of various river projects including a removal of out-aged hydraulic structures.

• Journal of Environmental Impact Assessment
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• v.21 no.6
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• pp.841-857
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• 2012

Preliminary ecological environmental assessments including physico-chemical constituents, water quality, fish fauna analysis, physical habitat health, and ecological health assessment were conducted as a primary step for Jeungchon micro-habitat ecosystem restoration in 2012. Water chemistry analysis of conductivity, dissolved oxygen, chlorophyll-a and etc. indicated that there were no significant differences(p < 0.05) among 6 sites between the headwaters and downstream. Multi-metric model analysis of Qualitative Habitat Evaluation Index(QHEI) showed that brooklets were at "good condition" as a mean QHEI of 158.7(n = 6) and the longitudinal differences of the model values between the sites were minor(QHEI range: 153 - 165). Total fish species and the number of individuals were 12 and 481, respectively, and dominant species were Zacco platypus(49.5%) and Zacco koreanus(36.8%). Tolerance guild analysis showed that the proportion of sensitive species($S_S$) had a negative linear function[$S_S=86.35-0.31(D_H)$; $R^2$ = 0.892, p < 0.01] with a distance from the headwaters, while the proportion of tolerant species($T_S$) had a positive linear function($R^2$ = 0.950, F = 90.28, p < 0.001) with the distance. Trophic feeding guild analysis showed that the proportion of insectivore species($I_n$) had a negative linear function($R^2$ = 0.934, p < 0.01) with a distance from the headwaters, while the proportion of omnivore species($O_m$) had a positive linear function($R^2$ = 0.958, p < 0.001) with the distance. Index of Biological Integrity(IBI) model, based on fish assemblages, showed a "fair condition" as a mean IBI of 23(n = 6), and there was a distinct differences of ecological health between the headwaters(S1 = 30; "good condition") and the downstreams(S6 = 14; "poor condition"). Overall, the preliminary environmental impact assessments suggest that water quality, physical habitat conditions(QHEI model), and ecological health(IBI model) were maintained well, even if the state was not an excellent conditions.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.822-829
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• 2011

The purpose of the present study is to estimate the ecological instream flow for conservation and restoration of fish habitat in running water ecosystem which has very important status for stream environment. Estimation of the ecological instream flow in the present study was carried out by application of a two-dimensional depth averaged model of river hydrodynamics, River2D model. It can model fish habitat in natural streams and rivers and assess the quality of physical habitat accoriding to the species preferences for habitat suitability. Zacco platypus and Zacco temmincki were selected as target fish species in the study area of the Seomjin river. The Habitat Suitability Criteria (HSC) developed by Sung et al. (2005) were used for target fish species, life stages and habitat conditions in the study. Weighted usable area (WUA) was computed by the River2D model considering preferences of target fish species for velocity, depth, and channel substrate. The result revealed that the ecological instream flow of $10.0m^3/s$ is needed to maintain the target fish habitat at each life stage in the river.