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1.
The estimation of the area of a stream reach suitable as habitat for an aquatic species by the Instream Flow Incremental Methodology is described. An important component of the methodology is PHABSIM, which is a collection of computer programs whereby useable stream area is computed as a function of discharge. This comprises a variety of options for both hydraulic and habitat simulation. A single data set is used to calculate the useable area at one discharge for three life stages of brown trout, using various options in habitat simulation. The results are shown to vary greatly according to the particular combination of options selected, so unless calculations are founded on biologically realistic assumptions the potential within PHABSIM for the ?fudging”? of results is considerable. 相似文献
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J. G. Williams 《河流研究与利用》2013,29(3):399-401
The bootstrap can be used to estimate confidence intervals for complex statistics such as weighted usable area, the habitat index calculated by the Physical Habitat Simulation System (PHABSIM) and related models. Use of the bootstrap entails sampling with replacement from the original sample, such as a set of PHABSIM transects. Because the method has been improperly applied to PHABSIM transects in several instances, I explain in detail why bootstrap sampling is with replacement. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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A bootstrap analysis was used to assess the variability in flow–habitat relationships for juvenile and adult rainbow trout (Oncorhynchus mykiss) in the Cache La Poudre River as a function of the number of Physical Habitat Simulation System (PHABSIM) transects. The bootstrap analysis was conducted by selecting without replacement different numbers of transects, ranging from six to 40, from a pool of 107 transects. The variability in flow–habitat relationships, as quantified by the 95% confidence interval for the flow with the peak habitat, decreased with increasing numbers of transects, and was greater for juveniles than for adults. The 95% confidence limits ranged from 9% for adult trout with 40 transects to 73% for juvenile trout with six transects. The results of this study can be used in negotiations for the number of transects selected during scoping of instream flow studies, as well as in assessing the relative confidence that should be placed in flow–habitat relationships for different species and life stages. Published in 2005 by John Wiley & Sons, Ltd. 相似文献
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C. S. Shirvell 《河流研究与利用》1989,3(1):277-289
PHABSIM, part of the Instream Flow Incremental Methodology, was used to predict the spawning habitat used by chinook salmon in a 600 m long section of the Nechako River, British Columbia, Canada. Predictions of the model were compared to the location and amount of habitat actually used by adult chinook salmon in 1974, 1980, and 1986. About 3800 m2 (70 per cent) of the spawning area actually used by the population were predicted as unusable by the ‘best’ prediction, while 87 per cent of the area predicted as usable has never had recorded use. The ‘best’ prediction resulted from using close transect spacing, frequent measurements along the transect, river-specific habitat suitability criteria, and modelling habitat at the fish's position near the stream bottom. Depending upon the spacing of the transects and the habitat suitability criteria used, PHABSIM predicted 210 per cent to 660 per cent more spawning habitat was available than historically had ever been used. Chinook salmon in the Nechako River spawn mainly on the upstream face of dunes, therefore, the assumption in PHABSIM that conditions predicted at the transects remain unchanged upstream and downstream part way to the adjacent transects was false. This assumption resulted in about two-thirds of the correct predictions being made for the wrong reason. The accuracy of PHABSIM's predictions for spawning might be improved by incorporating an index of river bottom topography or velocity gradient into the model. 相似文献
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The Instream Flow Incremental Methodology (IFIM) is a procedure that has been applied to the rivers of many countries to determine the relationship between discharge and a measure of the physical habitat area available to aquatic species. PHABSIM is a software package that is used to perform the calculations required for the IFIM procedure. Published data on instream macrophyte growth in chalk streams are used here to test the seasonal effects of plant growth in a hypothetical channel. The results show how these effects can significantly distort PHABSIM results. The predicted weighted useable area can differ by as much as 34% depending on the season used for the principal calibration of the Water Surface Profile module (WSP) of PHABSIM. An algorithm is proposed for use with PHABSIM which allows the effects of changes in macrophyte biomass to be included. 相似文献
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针对目前水电开发过程中忽视河流生物需水的现状,提出河道生物需水的理论,详细阐述了河道生物需水计算中要考虑的五种要素:生态、水文水力学、水质、地形学和河流廊道的连通性要素。介绍了国外广泛应用的IF IM方法及其应用和优缺点,并指出其在我国进行应用时应注意的问题。 相似文献
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Steven F. Railsback 《河流研究与利用》2023,39(5):987-992
This paper discusses why and how to use ecologically appropriate spatial resolutions (e.g., cell size or range of cell sizes) when modeling instream flow effects on aquatic animals. Resolution is important because relations between habitat and animal habitat use vary with spatial resolution, and different habitat variables may best predict habitat use at different resolutions. Using appropriate resolutions consistently would bring clarity and coherence to how we quantify and model habitat characteristics and habitat use by fish, facilitate the use of standard and more credible measures of habitat preference, incorporate more fisheries knowledge to improve models for different kinds of fish, and avoid well-known (and perhaps unknown) biases. Doing so involves describing habitat, and habitat use by fish, with spatially explicit measures with clear resolutions; using the same resolution for physical habitat and fish habitat use; selecting that resolution for ecological reasons; and using habitat variables and fish observation methods appropriate for the resolution. The choice of resolution considers factors such as how much space fish use for specific activities and the size of important habitat patches. For drift-feeders, cell sizes and fish habitat use observations should use a resolution no smaller than feeding territories. Piscivores typically hunt over large areas so should be modeled with larger habitat units. Models of small and less-mobile organisms (e.g., benthic invertivores) may need fine resolutions to capture the small areas of unusual habitat they depend on. Because of such differences, instream flow studies (like any spatial ecology exercise) should clearly state what resolution(s) they use and why. 相似文献
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The Physical Habitat Simulation System (PHABSIM) still probably remains as the most widespread habitat method used to establish inflow standards or to link habitat temporal variations with fish population dynamics. However, statistical uncertainties around the PHABSIM main output, the weighted usable area (WUA) over discharge curves, are usually ignored. Here, we assess the uncertainty in WUA curves and derived habitat duration curves induced by the variability around the PHABSIM biological model, the habitat suitability criteria, using brown trout Salmo trutta as the model species. Bootstrap analyses showed that the uncertainty around the WUA curves was rather high when bootstrap sample (BS) size was low and differed among age classes, being generally lower for young‐of‐the‐year (YOY). Width of 95% confidence intervals for maximum WUA magnitude increased with decreasing BS size, ranging from 19.3% for YOY trout at the largest BS size (40 transects, 270 habitat use observations) to 146% for juveniles at the smallest BS size (nine transects, 60 habitat use observations). The uncertainty arose primarily from the construction of the channel index variable. Nevertheless, results showed that the uncertainty in WUA values could be reduced down to acceptable levels by using general functional channel index categories. Likewise, the shape of WUA curves was also highly variable when BS was small. These patterns resulted in habitat duration curves being highly uncertain, much more in their amplitude than in their shape. Uncertainty about the flows corresponding to different habitat exceedance values increased with decreasing probability of exceedance. Width of peak flow confidence intervals ranged from 3.3% for YOY trout at the largest BS size to 226% for adults at the smallest BS size. Yet such levels of uncertainty do not necessarily entail critical errors in the decision‐making process because large variability in flow peak does not necessarily lead to large variability in WUA magnitude. 相似文献
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两变量设计洪水估计的不确定性及其对水库防洪安全的影响 总被引：5，自引：0，他引：5
在两变量水文频率分析中,样本系列容量一般较小,使得水文设计值估计具有不确定性。本文基于Copula函数和Parametric Bootstrap方法,并考虑联合设计值的最可能组合模式,建立可描述两变量设计洪水估计不确定性的C-PBU(Copula-based Parametric Bootstrap Uncertainty)模型,同时提出了定量评价两变量不确定性的度量指标,分析了联合设计值估计不确定性对水库最高调洪水位的影响,并对比了不同典型洪水选取模式下的水位不确定性。以隔河岩水库为例,推求了两变量设计值估计的95%置信区域;比较了不同样本容量对不确定性的影响。结果表明:设计洪水估计和典型洪水选择具有较大的不确定性,可采用C-PBU模型推求置信区间,来考虑设计洪水估计不确定性对水库防洪安全的影响。 相似文献
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The locations used by spawning Atlantic salmon (Salmo salar L.) in a reach of the Girnock Burn, Scotland, were monitored over three successive years. Reach discharge was estimated for each spawning observation using a conversion factor applied to continuous flow data from a gauge located in the catchment. Data on the availability and use of different discharges were used to construct a discharge electivity index for the reach. The index was compared to output from a Physical HABitat SIMulation (PHABSIM) model of the reach. Spawning fish used relatively high discharges, with the highest electivity value being for a discharge approximately three times the reach median flow. The electivity index and the PHABSIM weighted usable area (WUA) versus discharge curve were similar across the low flow range and both suggested similar optimum discharges for spawning (1.1 and 1.4 m3 s?1 respectively). However, electivity values suggested unsuitable conditions were reached at discharges greater than 1.4 m3 s?1 whereas PHABSIM predicted relatively high WUA values at discharges up to 2 m3 s?1. Electivity indices provide an insight into discharge selection that is not dependent on hydraulic simulations or assumptions about microhabitat (depth, velocity, substrate) preferences. Moreover, they can be used to assess discharge suitability in hydraulically complex streams where the one‐dimensional hydraulic models used by PHABSIM may be inappropriate. However, unlike PHABSIM, they cannot be used to predict the suitability of flows outside observed discharge ranges and so are limited in their application. Further work is required to refine the methodology and assess its transferability to other streams. Nonetheless, indices may represent a useful tool that can be used to complement other methods of assessing instream flow needs. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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We 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. 相似文献
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Disaster prevention planning is affected in a significant way by a lack of in‐depth understanding of the numerous uncertainties involved with flood delineation and related estimations. Currently, flood inundation extent is represented as a deterministic map without in‐depth consideration of the inherent uncertainties associated with variables such as precipitation, streamflow, topographic representation, modelling parameters and techniques, and geospatial operations. The motivation of this study is to estimate uncertainties in flood inundation mapping based on a non‐parametric bootstrapping method. The uncertainty is addressed through the application of non‐parametric bootstrap sampling to the hydrodynamic modelling software, HEC‐RAS, integrated with Geographic Information System (GIS). This approach was used to simulate different water levels and flow rates corresponding to different return periods from the available database. The study area was the Langat River Basin in Malaysia. The results revealed that the inundated land and infrastructure are subject to a flooding hazard of high‐frequency events and that the flood damage potential is increasing significantly for residential areas and valuable land‐use classes with higher return periods. The proposed methodology, as well as the study outcomes, of this paper could be beneficial to policymakers, water resources managers, insurance companies and other flood‐related stakeholders. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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Habitat suitability of brown trout (Salmo trutta fario) was studied in the upper portion of the Adda River, Northern Italy. Measurements were made for 528 individuals distributed in two life‐stage classes, adult and juvenile, based on body length. In order to provide basic biological information for the physical habitat simulation (PHABSIM) system of the instream flow incremental methodology (IFIM) in the Italian regulated rivers, habitat suitability curves (HSCs) have been developed with respect to several microhabitat riverine parameters. Initially, current velocity, water depth, substrate class size and cover were analysed with an univariate approach, then bivariate habitat suitability models were developed from depth and velocity data. The comparison of experimental univariate HSCs with those from the literature outlined some differences that can essentially be explained by characteristics of the investigated river, confirming the necessity of using site‐specific curves in relation to each experimental study area. To compare the univariate and bivariate approaches, the weighted usable area (WUA)–discharge relationships were calculated using both types of HSCs. Response curves obtained from the two approaches turned out to be quite different. In PHABSIM habitat modelling, HSCs univariate functions need to be aggregated to produce the WUA–discharge relationship. A multiplicative criterion is generally used for the combined suitability factor; by means of this aggregation criterion all variables have equal weight. According to bivariate models, depth is much more important than velocity in defining habitat suitability requirements. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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A procedure designed to test the transferability of habitat suitability criteria was evaluated in the Cache la Poudre River, Colorado. Habitat suitability criteria were developed for active adult and juvenile rainbow trout in the South Platte River, Colorado. These criteria were tested by comparing microhabitat use predicted from the criteria with observed microhabitat use by adult rainbow trout in the Cache la Poudre River. A one-sided X2 test, using counts of occupied and unoccupied cells in each suitability classification, was used to test for non-random selection for optimum habitat use over usable habitat and for suitable over unsuitable habitat. Criteria for adult rainbow trout were judged to be transferable to the Cache la Poudre River, but juvenile criteria (applied to adults) were not transferable. Random subsampling of occupied and unoccupied cells was conducted to determine the effect of sample size on the reliability of the test procedure. The incidence of type I and type II errors increased rapidly as the sample size was reduced below 55 occupied and 200 unoccupied cells. Recommended modifications to the procedure included the adoption of a systematic or randomized sampling design and direct measurement of microhabitat variables. With these modifications, the procedure is economical, simple and reliable. Use of the procedure as a quality assurance device in routine applications of the instream flow incremental methodology was encouraged. 相似文献
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Microhabitat preferences of adult brown trout (Salmo trutta m. fario) were monitored for the purpose of determining design parameters for river restoration. The habitat preferences were evaluated during the summer period of minimum flows. Since 1995, field measurements have been performed in 52 reaches in 43 mountain and piedmont streams. The relationship between hydraulic characteristics and the values of maximum habitat suitability derived from velocity and depth habitat suitability curves (HSCs) was statistically determined. Trout in natural stream reaches showed a strong degree of dependence on depths, but in regulated streams, they were dependent on velocities. The representative habitat suitability curves for four depth intervals were extrapolated. From these outputs, the optimum depths of a microhabitat for river restoration measures and/or assessment of the influence of water withdrawals can be derived. The influence of geological regions on the shape of HSCs has not been proved; therefore, it is conceivable that after verification, the generalized HSCs may also be valid in other mountain and piedmont regions. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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This paper reports the findings of research designed to assess the ability of PHABSIM to predict Atlantic salmon Salmo salar spawning habitat in the Girnock Burn, a tributary of the River Dee in northeast Scotland. It used an 18‐year spawning data record to assess: (a) the ability of PHABSIM to predict between‐year differences in the availability of habitat at the study site; (b) the ability of PHABSIM to predict patterns of relative suitability across the site; and (c) the influence of different Habitat Suitability Indices (HSIs) on the model's predictions with respect to (a) and (b). Predictions of between‐year and within‐site habitat availability based on ‘utilization’ and ‘preference’ HSIs developed in the Dee catchment corresponded significantly (chi‐squared and regression tests, P < 0.05) with the use of the site by spawning fish. However, predictions based on utilization HSIs developed in streams in southern England did not correspond significantly with patterns of site use. Results of the study indicate that PHABSIM is capable of predicting Atlantic salmon spawning habitat in upland streams such as the Girnock, but that the use of appropriate HSIs is critical. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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This 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. 相似文献