Habitat Simulation Research Articles

Long‐term brown trout populations responses to flow manipulation

AbstractDespite the many habitat simulations that have been undertaken around the world, not enough biological monitoring has been performed following flow manipulations. It is difficult, however, to refine flow management decisions without a better understanding of the links between amounts, durations and seasonality of flow deliveries and population dynamics.Trout populations were monitored before and after flow alterations in five trout streams, involving 17 study sites over a 4‐ to 12‐year period, depending on the sites.A comparison of the trout populations observed to theoretical habitat/population models pointed up several helpful lessons. Various factors slow increases in population size, including the availability and quality of spawning grounds, the general connectivity of the bypass section (BPS) and severe spate events. In addition to these site‐dependent factors, hydrological dynamics may explain why it is so difficult to clearly identify relationships between habitat availability and real fish stocks. Moreover, opportunities to observe population changes are improved when the pre‐enhancement instream flow value is very low, and when there is a considerable difference between pre‐ and post‐enhancement values. A population dynamics model that incorporates different habitat limitations and demographic background can be a very precious tool to improve understanding of the different situations and to build scenarios of population recovery. Copyright © 2008 John Wiley & Sons, Ltd.

Environmental flow methodologies to protect fisheries resources in human‐modified large lowland rivers

AbstractThe flow regimes of temperate large lowland rivers are manipulated to provide various services for society. Most water policy decisions are based on economic considerations, with little or no consideration toward fish conservation and fisheries. The prerequisite for a stronger implementation of these interests in water policy decisions is the development of appropriate tools for assessing the adequate flow needed to protect fish diversity and fisheries resources.From the 1970s onwards, environmental flow methodologies (EFMs) have been developed primarily to protect endangered fish species and to maintain fisheries resources in human‐modified rivers. Until now, their application had mainly been restricted to small upland rivers and headwater streams. Here, we investigate the applicability of commonly used EFMs for predicting and quantifying the consequences of flow manipulation on fish and fisheries of regulated large lowland rivers.Among the range of environmental flow methods currently available, habitat simulation methods are promising tools to assess adequate flow and to quantify the consequences of flow manipulation on the temporal and spatial availability of littoral habitats important for fish. However, habitat simulation methods may be effective only with those fish species whose recruitment is influenced by the availability of those habitats. To increase prediction accuracy, habitat simulation methods have to be linked to population dynamic models. More research is needed to improve understanding of the mechanisms controlling the dynamics of populations and assemblages in regulated large lowland rivers. Copyright © 2008 John Wiley & Sons, Ltd.

Trade-offs between microhabitat selection and physiological plasticity in the Antarctic springtail, Cryptopygus antarcticus (Willem)

In the maritime Antarctic, terrestrial arthropods have recourse to two strategies to mitigate low summer temperatures: (1) physiological plasticity and (2) avoidance via microhabitat insulation. This study investigated the interaction between these strategies in the springtail, Cryptopygus antarcticus, established in situ within contrasting microcosms (buffered vs. exposed) and within two sets of habitat simulations (wet vs. dry) over diurnal scales through the Antarctic summer. Significant differences were found in the cold hardiness of springtails sampled simultaneously from each microcosm. Exposed animals showed greater plasticity in the “true” austral summer, but as field temperatures declined preceding the onset of winter, buffered animals showed greater resilience. Overall, water was found to inhibit the buffering effect of moss and there was a significantly greater discrimination between buffered and exposed microcosms in the dry treatment. Analysis of microhabitat temperatures indicate that it is thermal variability not lower temperature that is responsible for the greater plasticity of exposed animals.

Eco-hydrology of the Pangani River downstream of Nyumba ya Mungu reservoir, Tanzania

Eco-hydrological studies are highly emphasized worldwide at the moment especially where hydraulic structures such as dams are concerned, mainly focusing on benefiting both humans and existing ecosystem for the present and future generations. The study at Pangani basin was aimed at assessing the sufficiency and the amount of flow reaching the downstream area of the Pangani River for maintenance of ecosystem. Fish species were considered as the indicators for ecosystem health. Flow duration curves (FDC) and hydrographs were developed by using the collected historical daily flow data and used for assessing the flow variation before and after Nyumba ya Mungu (NYM) dam construction. The results showed that there is no seasonality and that for most part of the year the flow is within 20–40 m 3/s. From the comparison it was found that there is 42.7% decrease in Q 5, 2.1% decrease in Q 95, 38.9% increase in Q 75, 23.4% increase in Q 50 and decrease of percentage exceedence of 50 m 3/s by 61.5%. Physical habitat simulation model (PHABSIM) was used for hydraulic simulation incorporating geometric and flow data collected in the field. From the simulations minimum flow for habitat protection is about 15 m 3/s and for flood formation flows should be greater than 50 m 3/s. Thus the required reservoir outflow for sustainable water resources management at the NYM should follow the above specifications.

피라미에 대한 보 철거 구간에서의 물리서식처 모의(PHABSIM) 적용

하천환경에 대한 사회적 요구에 의해 다양한 하천 복원 및 환경개선사업이 진행되고 있으므로, 이와 같은 사업의 효과를 평가할 방법론이 제공되어야 한다. PHABSIM은 하천 흐름과 관련되어 있는 수생 생물의 수리적 서식처 적합도를 평가하기 위해 제안된 방법이다. 본 연구에서는 보 철거 구간에 PHABSIM을 적용하여, 보 철거에 따른 피라미의 물리서식처 변화와 모형의 적절성을 평가하였다. 그 결과 일반적으로 보를 철거할 경우가 존치할 때보다 물리서식처가 향상된 것으로 나타났다. 그러나 유영력이 약한 산란기의 물리서식처는 보 상류의 유속이 증가되어 감소하는 것으로 나타났으며, 이에 대한 적절한 대책이 필요하다. 본 연구에 적용한 PHABSIM은 보 철거 사업을 포한한 다양한 하천사업의 평가와 필요성을 제시하는 효과적인 방법으로 활용될 수 있을 것이다. 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.

온천천 유지용수 공급에 따른 생태수문환경 변화분석

The eco-hydrologic effects of maintenance water supply on Oncheon stream are studied using hydrologic, hydraulic and ecologic models. SWMM (Storm Water Management Model) is used for long-term simulation of runoff quantity and water quality from Oncheon stream watershed. Using the output hydrologic variables from SWMM, HEC-RAS (River Analysis System) is then used to simulate the hydraulics of water flow through Oncheon stream channels. Such hydrologic, hydraulic and water quality output variables from SWMM and HEC-RAS are served as input data to execute PHABSIM (Physical Habitat Simulation) for the purpose of predicting the micro-habitat conditions in rivers as a function of stream flow and the relative suitability of those conditions to aquatic life. It is observed from the PHABSIM results that the weighted usable area for target fishes has the maximum value at of instream flow. However, mid and down stream areas that have concrete river bed and covered region are unsuitable for fish habitat regardless of instream flow increment. The simulation results indicate that the simple maintenance water supply is limited in its effect to improve the ecological environment in Oncheon stream. Therefore, it is imperative to improve water quality and to recover habitat conditions simultaneously.

Comparison of MesoHABSIM with two microhabitat models (PHABSIM and HARPHA)

AbstractThis study demonstrates how using different habitat models can influence the results of instream habitat assessment and conclusions for river management. We used three models for a portion of the Quinebaug River (Connecticut and Massachusetts, USA): a simplistic microhabitat model with univariate habitat‐use criteria and substrate‐based channel index (the Physical Habitat Simulation Model (PHABSIM)); a microhabitat model using multivariate criteria including a wide range of cover attributes (HARPHA); and a mesohabitat model with multivariate habitat‐suitability criteria (MesoHABSIM). The flow‐habitat rating curves produced by each model were compared at two scales: site and study segment. To investigate the impact of model choice on answering questions such as which location or flow provides more habitat, we applied Spearman's correlation of ranks. The relationship between habitat‐suitability predictions and fish presence at the same location was investigated with dedicated fish observations. The study showed that: (1) of the tested models, only MesoHABSIM predictions correlated with fish observations; (2) the variation within microscale models (PHABSIM and HARPHA) was greater than between micro‐and mesoscale models (HARPHA and MesoHABSIM); and (3) simple univariate habitat‐use criteria provided the largest source of discrepancies among the models. We suggest that these differences may lead to erroneous conclusions, especially if flow‐habitat rating curve analysis is considered an endpoint of instream flow study. Copyright © 2007 John Wiley & Sons, Ltd.

The MesoHABSIM model revisited

AbstractThe MesoHABSIM simulation model was developed in 2000 as an enhancement of the habitat descriptions used in the physical habitat simulation model (PHABSIM). MesoHABSIM integrates system‐scale assessment of ecological integrity in flowing waters with quantitative information on physical habitat distribution to simulate habitat changes at the watershed scale. The goal was better integration of physical habitat models into river management by ‘upscaling’ to address issues relevant at management levels. This paper describes the most updated version of the MesoHABSIM approach resulting from the experience gained during the application of the model in projects since 2000. Copyright © 2007 John Wiley & Sons, Ltd.

Concept and application of the usable volume for modelling the physical habitat of riverine organisms

AbstractMost physical habitat models such as PHABSIM (Physical HABitat SIMulation) calculate the Usable Area (UA) of the river surface or the riverbed as an indicator for the available habitat for a species of interest. Although these models have been widely applied, the three dimensionality of habitat hydraulics is increasingly being recognized as an essential issue for understanding the ecological needs of aquatic organisms. This paper describes the modular toolbox HaMoSOFT (Habitat Modelling SOFTware) which quantifies the available habitat as the Usable Volume (UV) for each class of depth, flow velocity, substrate and cover and for all possible class combinations. The toolbox was calibrated in an artificial river under laboratory conditions. Optimal grids for field sampling were defined by comparing model results based on reduced sampling densities. The UV of a natural river stretch, the Schwechat River in Austria, was analysed at different discharges to assess the impact of flow changes on model outputs. UA and UV percentages were modelled for five cross‐sectional datasets, one collected in the artificial river, one in the Zwalm River (Belgium) and three in the Schwechat River at different discharges. UA percentages appeared to be higher than those of UV for lower flow velocity classes in all natural rivers and for lower depth classes in all rivers. Analysis of the Usable Volumes for the three Schwechat River scenarios revealed the observed trends were independent of flow changes. The results indicate HaMoSOFT is an interesting tool to overcome some shortcomings of Weighted Usable Area (WUA) modelling. Since the UV method is a trade‐off between the practical needs for model application in river management and the complexity of the three‐dimensional hydraulic models, it may be a practical approach for realistic physical habitat quantification. Copyright © 2007 John Wiley & Sons, Ltd.

Generalisation of physical habitat-discharge relationships

Abstract. Physical habitat is increasingly used worldwide as a measure of river ecosystem health when assessing changes to river flows, such as those caused by abstraction. The major drawback with this approach is that defining precisely the relationships between physical habitat and flow for a given river reach requires considerable data collection and analysis. Consequently, widely used models such as the Physical Habitat Simulation (PHABSIM) system are expensive to apply. There is, thus, a demand for rapid methods for defining habitat-discharge relationships from simple field measurements. This paper reports the analysis of data from 63 sites in the UK where PHABSIM has been applied. The results demonstrate that there are strong relationships between single measurements of channel form and river hydraulics and the habitat available for target species. The results can form the basis of a method to estimate sensitivity of physical habitat to flow change by visiting a site at only one flow. Furthermore, the uncertainty in estimates reduces as more information is collected. This allows the user to select the level of investment in data collection appropriate for the desired confidence in the estimates. The method is demonstrated using habitat indicators for different life stages of Atlantic salmon, brown trout, roach and dace.

Relating Narrative, Inquiry, and Inscriptions: Supporting Consequential Play

In this paper we describe our research using a multi-user virtual environment, Quest Atlantis, to embed fourth grade students in an aquatic habitat simulation. Specifically targeted towards engaging students in a rich inquiry investigation, we layered a socio-scientific narrative and an interactive rule set into a multi-user virtual environment gaming engine to establish a virtual world through which students learned about science inquiry, water quality concepts, and the challenges in balancing scientific and socio-economic factors. Overall, students were clearly engaged, participated in rich scientific discourse, submitted quality work, and learned science content. Further, through participation in this narrative, students developed a rich perceptual, conceptual, and ethical understanding of science. This study suggests that multi-user virtual worlds can be effectively leveraged to support academic content learning.

MODELING A RIGHTS‐BASED APPROACH FOR MANAGING HABITAT IMPACTS OF FISHERIES

ABSTRACT. Limiting adverse consequences of fishing on essential fish habitat has emerged as a key fishery management objective. The conventional approach to providing habitat protection is to create MPAs or marine reserves that prohibit all or certain types of fishing in specific areas. However, there may be more cost‐effective and flexible ways to provide habitat protection. We propose an individual habitat quota (IHQ) system for habitat conservation that would utilize economic incentives to achieve habitat conservation goals cost‐effectively. Individual quotas of habitat impact units (HIU) would be distributed to fishers with an aggregate quota set to maintain a target habitat “stock.” HIU use would be based on a proxy for marginal habitat damage. We use a dynamic, explicitly spatial fishery and habitat simulation model to explore how such a system might work. We examine how outcomes are affected by spatial heterogeneity in the fishery and the scale of habitat regulation. We find that the IHQ system is a highly cost‐effective means of ensuring a given level of habitat protection, but that spatial heterogeneity and the scale of regulation can have significant effects on the distribution of habitat protection.

Validation of Chinook fry behavior‐based escape cover modeling in the lower Klamath River

An emerging trend in the state‐of‐the‐art instream flow assessment applications is the use of three‐dimensional channel topography coupled with two‐dimensional hydrodynamic models. These components are most often integrated with biological response functions for depth, velocity, and substrate to simulate physical habitat for target species and life stages. These approaches typically involve the simple extension of the one‐dimensional conceptual habitat models represented by the Physical Habitat Simulation System (PHABSIM) developed by the U.S. Fish and Wildlife Service (Stalnaker, 1995). However, as demonstrated in this paper, the physical habitat based template represented by high‐resolution channel topography and two‐dimensional hydrodynamic model outputs can extend these simple conceptual models of habitat to incorporate additional behavior‐based decision rules. The approach demonstrated in this paper evaluates the spatial suitability of physical habitat for chinook fry based on the incorporation of behavioral rule sets associated with instream object cover (i.e., velocity refuges) and in‐water escape cover type and distance. Simulation results are compared to simplistic based physical habitat simulations using only depth, velocity, and substrate and validated against independent fish observation data. Results demonstrate that the functional relationship between predicted habitat and discharge utilized in many instream flow assessments is significantly different when the additional behavior‐based decision rules are applied.

Response of the benthic macroinvertebrate community in a northern Michigan stream to reduced summer streamflows

AbstractWe evaluated the response of benthic macroinvertebrates in a Michigan trout stream to flow reduction by diverting water from a 602 m reach of Hunt Creek from June through August of 1994, 1997 and 1998. We also assessed the utility of the Physical Habitat Simulation system (PHABSIM) in predicting the response of benthic insects to water withdrawals by testing the assumption of a positive linear relationship between modelled habitat (weighted usable area, WUA) and the density of 13 benthic insect families. Our findings showed that the density of filter feeding and grazing insect taxa, as well as insects classified as obligate erosional zone taxa, declined significantly in the dewatered (treatment) zone (TZ) when 90% of flow was diverted. Density of Ephemeroptera, Plecoptera and Trichoptera (EPT) taxa in the TZ was significantly lower when 90% of water was diverted as compared to density at baseflow or when flow was reduced by 50%. The density of all insects in an upstream reference zone riffle (RZ), where flow was not altered, did not change among experimental periods. Although overall reductions in the density of benthic insects at 90% flow reduction coincided with lower PHABSIM predictions of WUA, we found poor linear correlation between WUA at different flows and the density of the 13 benthic insect families for which WUA was modelled. The low proportion of variation explained by WUA for all families modelled suggests that WUA alone is not an accurate predictor of benthic insect density. Resource managers should consider the potential consequences of water withdrawals to all components of stream communities, including benthic macroinvertebrates. However, caution should be applied when using the PHABSIM technique in groundwater‐fed streams such as Hunt Creek, because most relationships between WUA and benthic insect density were insignificant. Copyright © 2006 John Wiley & Sons, Ltd.

Evaluation of instream habitat enhancement options using fish habitat simulations: case-studies in the river Pas (Spain)

In the northern coast of Spain there are rivers with Atlantic salmon populations. In the upper reaches of one of these streams, river Pas, the effectiveness of habitat enhancement measures was evaluated, under different instream flow conditions. By means of the Instream Flow Incremental Methodology and using a two dimensional hydraulic model (River2D, Steffler P (2000) Software River2D. Two Dimensional Depth Averaged Finite Element Hydrodynamic Model. University of Alberta, Canada), the potential value of stream habitat for different salmon development stages requirements was measured by Weighted Useable Area (WUA). This habitat evaluation was carried out for the unmodified stream reach, which represent the control or natural conditions. Habitat improvement measures (alternate deflectors and low dams) were simulated in the original riverbed topography. Over this modified base, habitat was estimated running River2D again. By comparing the salmon habitat evaluations in the control conditions with those obtained under those improvement conditions we have been able to assess the effectiveness of each one, and the instream flow environment at which maximum improvement is reached. The maximum habitat improvement was obtained around 10 m3/s for the adult salmon, and for the fry and parr it was around 6 m3/s. However, the habitat simulation results show that with both improvement measures, under a natural flow regime the mean annual habitat increases around 1% of the WUA in relation to the control conditions, which is not a significant improvement. A similar small WUA increase was obtained when changing the bed topography, considering geomorphological adjustments due to the new erosion and sedimentation areas caused by the presence of these structures. Therefore, these types of habitat improvement measures are not recommended in these stream reaches.

An application of physical habitat modelling to quantify ecological flow for the Rheinau hydropower plant, River Rhine

The meander of the River Rhine at the Swiss-German hydropower plant Rheinau suffers from residual flow (5 m 3 /s vs. 372 m 3 /s mean flow). As a consequence, fish and benthic communities have shifted from lotic to lentic, and ubiquous species are more abundant. The simulation model CASiMiR, linking hydraulic and morphological conditions (water depth, flow velocity, near-bottom hydraulic forces) with ecological requirements of fish and benthos, was applied to assess habitat suitability for lotic species. Various scenarios of discharge and changes in the operation of two additional weirs located within the residual water stretch were considered. Model calculations showed that good quality habitats can be achieved either by significantly increasing residual flow and unchanged weir position (90-130 m 3 /s) or by lowering the weirs and moderately increasing discharge (20-70 m 3 /s). Seasonal variation in discharge and additional ecomorphological restoration are further options to optimize the living conditions for aquatic fauna. The suggested technical operation of the weirs allows an additional 60-70 m 3 /s to the turbines without lowering the habitat availability for fish indicator species. Hence, it can reduce the loss of energy production from about 30 to 6 % (other feasible measures such as additional turbines using the provided residual discharge are. not implied). In conclusion, such hydraulic habitat simulations can quantify the ecological impacts of technical alternatives and enable an objective, appropriate balance of ecological and economic benefits. Therefore, this kind of investigation may mitigate the controversy among stakeholders.

Developing a toolkit for fish passage, ecological flow management and fish habitat works

Fish passage, including fishways and fish screens, ecological flow management for open or ice-covered waters and fish habitat works, such as stream rehabilitation, habitat replacement, erosion and sediment management, are the subject of increased interest worldwide. Research and development in these areas, establishing a foundation of sound science and innovative engineering, has intensified, as a result of widespread recognition of the importance of sustainable and environmentally acceptable use of water resources. Scientific and engineering studies, along with technological advancements have allowed the development of a range of methods and tools for assessing the feasibility of and for providing guidance in seeking effective solutions. Methods and tools range from fairly simple to fairly sophisticated, from long-life rigid structures to adjustable ones, and solutions that are applicable at a variety of projects, scales, site conditions, fish species, aquatic biota, data sources and economic circumstances. A set of tools and methods is presented, which together form a toolkit under development. Each tool is at a different stage of advancement and the process of development is outlined. The toolkit includes analytical methods for relating fish migration timing to hydrographs, ways of attracting and guiding fish to fishways, analysis of fishway hydraulics and fish passage abilities, fish screen hydraulics and fish responses, nature-mimicking fish habitat structures, hydrodynamic and habitat simulation, and the initial stages of considering sediment and ice processes. Suggestions are made for further research and development in these interdisciplinary areas, which challenge interested researchers to focus their individual studies on fish passage, habitat and ecological issues and improve available tools.

영천댐 건설이 금호강의 어류 서식환경에 미치는 영향에 관한 평가

금번 연구에서는 금호강의 금호 수위관측소 지점에서 영천댐 건설에 따른 유황분석을 하였다. 분석 결과, 영천댐 건설 전에는 갈수랑 <TEX>$10.49\;m^3/s$</TEX>, 저수량 <TEX>$13.30\;m^3/s$</TEX>, 평수랑 <TEX>$15.65\;m^3/s$</TEX>, 풍수량 <TEX>$25.00\;m^3/s$</TEX> 이었으나, 건설 후에는 갈수량이 <TEX>$2.07\;m^3/s$</TEX>, 저수랑 <TEX>$2.89\;m^3/s$</TEX>, 평수량 <TEX>$4.0\;m^3/s$</TEX>, 풍수량 <TEX>$9.36\;m^3/s$</TEX> 으로 유황이 상당히 열악해 진 것으로 분석되었다. 유지유량 증분법의 물리적 서식처모의 모형을 적용하여 피라미의 성장단계별 가중된 가용면적-유량 관계곡선을 작성하였다. 이 관계곡선으로 유지 가능일 수를 초과확률로 가중된 가용면적의 서식처 현황곡선을 작성하고, 영천댐건설에 따른 하천의 유황변화가 어류 서식환경에 미치는 영향을 평가하였다. 평가결과, 산란기와 성어기 모두 영천댐건설에 따라 가중된 가용면적이 감소하여 어류 서식환경이 저하되었다. 그러나 산란기중 유량의 초과확률 <TEX>$90\;\%$</TEX> 이상에서는 영천댐에서 하류지역의 관개용수를 공급함으로써 유황이 개선되고 가중된 가용면적도 증가하여 어류서식환경이 개선된 것으로 평가되었다. In this study, flow duration analysis was conducted at the Gumbo stage gauging station due to construction of the Youngchun dam. The flow duration characteristics were <TEX>$10.49\;m^3/s$</TEX> of drought flow, <TEX>$13.30\;m^3/s$</TEX>. of low flow, <TEX>$15.65\;m^3/s$</TEX> of normal flow, and <TEX>$25.00\;m^3/s$</TEX> abundant flow before construction of Youngchun dam. But after construction of Youngchun dam, the flow duration characteristics were <TEX>$2.07\;m^^3/s,\;2.89\;m^3/s,\;4.0\;m^3/s,\;9.36\;m^3/s$</TEX> and they had been deteriorated. Applying the Physical Habitat Simulation Model by Instream Flow Incremental Methodology, the Weighted Usable Area(WUA)-Discharge Curve was developed for Zacco Platypus according to the growth stages. Using the WUA-Discharge Curve, the WUA Duration Curve was developed with exceedance probability of daily flow and evaluated fish habitat conditions due to the construction of Youngchun dam. As an evaluation result, the WUA was reduced and fish habitat environment was deteriorated due to the construction of Youngchun dam during the spawning and growth period of Zacco Platypus. However the exceedence probability of the <TEX>$90\;\%$</TEX>, irrigation water supply from the Youngchun dam improved flow duration characteristics and Weighted Usable Area as well as fish habitat.

Individual habitat quotas for fisheries

Fishery managers in the US are required to identify and limit adverse consequences of fishing on essential fish habitat. We propose an individual habitat quota (IHQ) system for habitat conservation that would utilize economic incentives to achieve habitat conservation goals cost-effectively. Individual quotas of habitat impact units (HIU) would be distributed to fishers with an aggregate quota set to maintain a target habitat “stock”. HIU use would be based on a proxy for marginal habitat damage. We use a dynamic, explicitly spatial fishery and habitat simulation model to explore the cost-effectiveness of achieving specified habitat conservation targets with our IHQ system versus fixed or rotating marine protected areas (MPAs). We find that the IHQ system can be considerably more cost-effective than MPAs, but that the relative advantage decreases as fish diffusion rates and uncertainty about fish distribution increases.

하천의 어류 서식환경을 고려한 생태학적 추천유량 산정

금번 연구는 낙동강 유역의 영강, 위천, 회천, 거창위천, 청도천, 단장천에서 산란기와 성어기에 어류의 서식과 수심, 유속, 하상재료 등 수리학적 특성에 관한 자연과학과 공학의 학제간 상호 연계조사를 시행하였으며, 어종별(피라미와 갈겨니), 성장단계별(산란기와 성어기), 서식처조건별(수심, 유속과 하상재료) 어류 서식 적합도 기준을 작성하였다. 유지유량 증분법 개념의 물리적 서식처 모의시스템을 적용하여, 낙동강 유역의 주요 하천에서 어류서식에 적합한 유량을 산정하고, 그 중 가장 큰 유량값을 생태학적 추천유량으로 결정하였다. 금번 결정한 생태학적 추천유량은 내성천 <TEX>$6.5\;m^3/s$</TEX> 등 <TEX>$5.0\;m^3/s{\sim}10.0\;m^3/s$</TEX> 이었다. 또한 생태학적 추천유량과 기존에 산정된 생태계 필요유량 및 유황분석 결과를 비교<TEX>${\cdot}$</TEX>검토 하였다. The detailed interdisciplinary surveys were conducted on the pattern of habitat use of dominant fishes during the spawning and adult stage. The hydraulic parameters of the depth and velocity, discharge, substrate cover streams, and distribution of fish in the Yeonggang, WiCheon, HoeCheon, GeochangwiCheon, CheongdoCheon, DanjangCheon (the Nakdong River Basin) were measured. The Habitat Suitability Criteria was developed for the two fish species (Zacco Platypus and Zacco Temmincki) and life stages(spawning and adult), habitat conditions (depth, velocity and covet). The Physical Habitat Simulation of the Instream Flow Incremental Methodology was applied to calculate for optimal flow and the ecological flow recommendation was proposed by choosing the largest one in the optimal flow. The ecological flow recommendation was <TEX>$5.0\;m^3/s{\sim}10.0\;m^3/s$</TEX> (e.g., <TEX>$6.5\;m^3/s$</TEX> in the NaeseongCheon). Also, the ecological flow recommendations were compared with the existing ecological flow and flow duration analysis.