• Journal of Korea Water Resources Association
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• v.42 no.6
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• pp.481-491
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• 2009

In this study, a comprehensive field monitoring was conducted to understand habitat conditions of fish species in the upper Geum river. Based on the monitoring data, riverine health conditions such as composition ratio of fish species, richness and dominance indexes, bio-diversity (dominance index, diversity, evenness and richness), and index of biological integrity were assessed, and optimal ecological flowrates were estimated using the habitat suitability indexes established for three fish species Coreoleuciscus splendidus, Zacco platypus and Pseudopungtungia nigra selected as icon species using the physical habitat simulation system (PHABSIM). The total number of species sampled was 20 species, and two sensitive species of C. splendidus (22.4%) and Z. platypus (22.0%) dominated the fish community. The estimated IBI values ranged from 34 to 42 with average being 38 out of 50, rendering the site ecologically fair to good health conditions. An optimal ecological flowrate of 9.0 cms was recommended for the representative fish species at the site.

• Journal of Ecology and Environment
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• v.39 no.1
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• pp.43-49
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• 2016

Fishways are constructed to provide longitudinal connectivity of streams or rivers where their flow has been altered by in-stream structures such as dams or weirs. Nature-like fishways have an additional function of providing fish habitats. In the study, we estimated the role of a nature-like fishway (length: 700 m, slope: 1/100) for fish habitat by using two dominant species in the Sangju Weir, Nakdong River, to calculate the optimal ecological flow rate using Physical HABitat SIMulation (PHABSIM). To identify the dominant species that used the fishway, we conducted trap monitoring from August to November 2012 at the fishway exit. The dominant species were Zacco platypus and Opsariichthys uncirostric amurensis with a relative abundance of 62.1% and 35.9%, respectively. Optimal habitat suitability indices (HSIs) for Z. platypus and O. u. amurensis were calculated as 0.6-0.8 m/s (water velocity) and 0.2-0.4 m (water depth), and 0.5-0.7 m/s (water velocity) and 0.1-0.3 m (water depth), respectively. The optimal ecological flow rates (OEFs) for Z. platypus and O. u. amurensis were 1.6 and 1.7 cubic meter per second (CMS), respectively. The results of the study can be used in a management plan to increase the habitat function of nature-like fishways in the Sangju Weir. This methodology can be utilized as an appropriate tool that can determine the habitat function of all nature-like fishways.

• 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 Korea Water Resources Association
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• v.46 no.3
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• pp.267-276
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• 2013

An Improvement of channel structure for sound fish habitat suitability enhancement is investigated. The restoration target species of Zacco Koreanus which is represented a sound aquatic ecosystem is selected by investigating results of the fish fauna and the river environments. The changes of lower channel width for enhancing suitability indices for water velocity and depth result in habitat suitability enhancement in general by PHABSIM simulation. The habitat suitability enhancement is not guaranteed consistently by the changes of lower channel is confirmed. The optimal lower channel widths at each reach are presented by genetic algorithm of optimization which is considering the enhancement of suitability indices for water velocity and depth with given instream flows. The suggested plan of the lower channel modification will contribute to the various projects for the environmental improvement of aquatic system.

• Journal of Korea Water Resources Association
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• v.37 no.11
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• pp.915-927
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• 2004

The purpose of this paper is to estimate the instream flow of the South Han River Basin to ensure an adequate supply of suitable quality of water for preservation and enhancement of aquatic ecosystems. Proposed methods is Physical Habitant Simulation System of Instream Flow Incremental Methodology. Accurate estimation on a water depth and a velocity distribution was acquired by applying a two dimensional hydrodynamic model for a simulation of a hydraulic parameter necessary for the habitat evaluation to be used in a physical habitat simulation system. The Habitat Suitability Criteria with the application of univariate curve on zacco platypus as a representative fish was able to be established by conducting a field investigation. The establishment of a hydrological materialistic balance between upper and lower streams was confirmed by conducting a simulation simultaneously together with a mainstream section, which was excluded from the considered sections for the inhabitation evaluation of fish.

• Ecology and Resilient Infrastructure
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• v.2 no.1
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• pp.33-41
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• 2015

In this study, an optimal improvement method of stream channel structure is presented for the enhancement of fish habitat suitability by genetic algorithm. The correlation between fish habitat suitability and physical disturbance in stream is analyzed according to the changes of hydraulic characteristics by channel structure rehabilitation. Zacco koreanus which is an indicator fish of the soundness of aquatic ecosystem was selected as a restoration target species by investigating the community characteristics of fish fauna and river environments in Wonju stream. The habitat suitability is investigated by PHABSIM with the habitat suitability index of Zacco koreanus. Hydraulic analysis by HEC-RAS and physical disturbance evaluation in stream are carried out. The optimal channel width modified for the enhancement of fish habitat suitability is provided. The correlation analysis between habitat suitability and physical disturbance with the change of hydraulic characteristics by channel modification showed that the proper channel modification enhanced fish habitat suitability and mitigated physical disturbance in the stream. The improvement of physical disturbance score by the channel structure rehabilitation for the enhancement of fish habitat suitability was confirmed in this study.

• Journal of The Geomorphological Association of Korea
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• v.28 no.2
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• pp.1-13
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• 2021

It is very important to secure sufficient river maintenance flow for the ecosystem, since the ecosystem in the downstream section of the dam is greatly affected by the stream maintenance flow from the dam. However, the amount of discharge from the Seomjingang Dam is decreasing year by year, this study estimated the ecological flow required for the downstream section of the Seomjingang Dam, which is known as the habitat of the endangered Acheilognathus somjinensis, in order to secure the river flow of the Seomjingang Dam. For this purpose, the proper discharge was calculated using the PHABSIM model, which is a hydrological survey and physical habitat simulation method, and the proper discharge of other fish species were also comprehensively reviewed. As a result of this study, the current river maintenance flow at the Seomjingang Dam partially satisfies the ecological maintenance flow including the Acheilognathus somjinensis in the downstream section of the Seomjingang Dam. However, this is recognized as the minimum discharge to maintain the ecology in the downstream section of the Seomjingang Dam, and it would be more desirable to secure larger river maintenance flow than this. This study can contribute the determination of the river maintenance flow of the Seomjingang Dam by proposing the river maintenance flow considering the fish habitat environment in the river.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.811-822
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• 2019

Environmental flows in the downstream sections of Yongdam Dam, Wonju Stream Dam, and Hongcheon River were estimated with selected target fish species such as Nigra for the site of Yongdam Dam, Splendidus for the site of Wonju Stream Dam, and Signifer for the site of Hongcheon River by considering endangered and domestic species. Physical habitat analysis was performed to estimate environmental flows for the study sites by applying the Physical Habitat Simulation (PHABSIM) and RIVER2D which combined hydraulic and habitat models. Based on the monitored data for ecological environment, the Habitat Suitability Index (HSI) for the target species was estimated by applying the Instream Flow and Aquatic Systems Group (IFASG). In particular, based on the result of fish monitoring, the HSI for each stage of the growth for target species was analyzed. As a result, the Weighted Usable Area (WUA) was maximized at $4.9m^3/s$ of flow discharge during spawning, $5.8m^3/s$ during the period of juvenile, and $8.9m^3/s$ during the adult fish season at the downstream section of Yongdam Dam. The result of the Wonju Stream Dam showed an optimal environmental flow of $0.4m^3/s$, $1.0m^3/s$, and $1.5m^3/s$ during the period of spawning, juvenile, and adult. The habitat analysis for the site of Hongcheon River, which is a non-regulated stream, produced an optimum environmental flow of $5m^3/s$ in the spawning period, $4m^3/s$ in the juvenile stage and $6m^3/s$ in the adult stage.

• Journal of Wetlands Research
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• v.10 no.3
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• pp.57-68
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• 2008

For improving water quality and hish habitat environment the targeted instream flows added to the field measurement of low flow at each reach along Wonju Cheon are calculated by depth, velocity, and the present lower channel width with considering the landscape, aquatic environment, and natural ecological function. Target instream flow increasing ranged from $0.03m^3/s$ of upstream to $0.90m^3/s$ of downstream according to the proposed depths of 0.10m to 0.30m and velocity of 0.2m/s. The methods for target instream flow increasing are base flow increasing by watershed management, non polluted discharge inflow from valley and combined sewer by sewerage system modification, and discharges from upstream reservoirs and detention basins near-by stream. The possible increasing flow rates are $0.19m^3/s$ to $3.42m^3/s$ which are 1.4 to 2.5 times of low flow to be measured which are the equivalent targeted instream flows along Wonju Cheon. The BOD-based water quality improvement are analyzed by QUAL2E. The habitat suitability indices by PHABSIM of Zacco temmincki as target species at middle stream of Wonju Cheon improve significantly by low flow increasing, which is very important to improve water quality and fish habitat.

• Journal of Environmental Science International
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• v.22 no.8
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• pp.925-935
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• 2013

In this study, a comprehensive field monitoring was conducted to understand habitat conditions of fish species in up and downstream of Hoengseong Dam. Based on the monitoring data, riverine health conditions such as composition ratio of fish species, bio-diversity (dominance index, diversity, evenness and richness), index of biological integrity (IBI) and qualitative habitat evaluation index (QHEI) were assessed, and optimal ecological flowrates (OEF) were estimated using the habitat suitability indexes (HSI) established for three fish species Coreoleuciscus splendidus, Pungtungia herzi and Microphysogobio longidorsalis selected as icon species using the physical habitat simulation system (PHABSIM). The total number of species sampled was 20 species, and two species of Zacco platypus (30.4%) and C. splendidus (20.9%) dominated the fish community. As a result, it was revealed that IBI and QHEI values decreased from upstream to downstream along the river. The estimated IBI value ranged from 24 to 36 with average being 30.9 out of 50, rendering the site ecologically fair to good health conditions. HSI for C. splendidus were determined according to three different month in terms of season: Spring (April), Summer (August) and Autumn (October). HSI for flow velocity were estimated at 0.7 to 0.8 m/s for the Spring, 0.5 to 1.0 m/s for the Summer and 0.8 to 0.9 m/s for the Autumn. HSI for water depth were estimated at 0.3 to 0.5 m for the Spring; 0.3 to 0.5 m for the Summer; and 0.3 to 0.4 m for the Autumn. OEF was estimated at 4.2 and $6.5m^3/s$ for the Spring and Autumn, and $12.0m^3/s$ for the Summer. Overall, it was concluded that the Hoengseong Dam has been relatively well protected from the anthropogenic disturbance for the legally protected species including the endemic species studied in this study.