andy ward | Ohio State University (original) (raw)

Papers by andy ward

Self-Sustaining Solutions for Streams, Wetlands, and Watersheds, 12-15, September 2004, 2004

... 25 10162 22495 10148 546 247 246 50 11809 30121 11141 663 260 274 100 13456 37488 12148 786 2... more ... 25 10162 22495 10148 546 247 246 50 11809 30121 11141 663 260 274 100 13456 37488 12148 786 282 301 Ditch Geometry and Two-Stage Design A survey of a 2100 ft length of ditch was performed by Joe Draper, Erick Powell, and Andy Ward on July 17, 2003. ...

2002 Chicago, IL July 28-31, 2002, 2002

The objectives of the study were: (1) to evaluate the ability of an empirically based equation to... more The objectives of the study were: (1) to evaluate the ability of an empirically based equation to predict the streamway width required to allow a stream to self-adjust its meander pattern; (2) to evaluate the influence of urbanization, floodplain width, and incision on bed load transport, the size of particle moved at incipient motion at flows approximating the effective discharge, and flood stage for the 100 year recurrence interval event; and to determine if knowledge obtained from Objectives 1 and 2 could b e used to develop stream setback guidelines that would help avoid channel instability problems typically associated with urbanization. Empirical and practical theoretical methods were used on 6 watersheds in central Ohio. The results showed that the extent of the meander pattern for all of the watersheds was well represented by the empirical streamway width equation. An analysis of flow and bed load transport in a compound twostage channel was performed for a series of different magnitude events that might occur during a 100 year period. The results showed that 1) floodplain width reduction, 2) entrenchment and 3) changes in flow regime each had a high potential to increase bed load transport and collectively changes in all these factors could result in a five to fifteen fold increase. The recommended approach is to establish setbacks that are a function of the meander belt width as calculated by an empirical equation that is based on the drainage area. Also, land uses within the setback zone should be restricted to uses that sustain or enhance the ecological function of the system and accommodate the stream in a state of dynamic equilibrium. Based on a previous study by the authors it is also recommended that storm water management strategies be used expressly to control bed load sediment transport rates.

Self-Sustaining Solutions for Streams, Wetlands, and Watersheds, 12-15, September 2004, 2004

... 25 10162 22495 10148 546 247 246 50 11809 30121 11141 663 260 274 100 13456 37488 12148 786 2... more ... 25 10162 22495 10148 546 247 246 50 11809 30121 11141 663 260 274 100 13456 37488 12148 786 282 301 Ditch Geometry and Two-Stage Design A survey of a 2100 ft length of ditch was performed by Joe Draper, Erick Powell, and Andy Ward on July 17, 2003. ...

Self-Sustaining Solutions for Streams, Wetlands, and Watersheds, 12-15, September 2004, 2004

... 25 10162 22495 10148 546 247 246 50 11809 30121 11141 663 260 274 100 13456 37488 12148 786 2... more ... 25 10162 22495 10148 546 247 246 50 11809 30121 11141 663 260 274 100 13456 37488 12148 786 282 301 Ditch Geometry and Two-Stage Design A survey of a 2100 ft length of ditch was performed by Joe Draper, Erick Powell, and Andy Ward on July 17, 2003. ...

The objectives of the study were: (1) to evaluate the ability of an empirically based equation to... more The objectives of the study were: (1) to evaluate the ability of an empirically based equation to predict the streamway width required to allow a stream to self-adjust its meander pattern; (2) to evaluate the influence of urbanization, floodplain width, and incision on bed load transport, the size of particle moved at incipient motion at flows approximating the effective discharge, and flood stage for the 100 year recurrence interval event; and to determine if knowledge obtained from Objectives 1 and 2 could b e used to develop stream setback guidelines that would help avoid channel instability problems typically associated with urbanization. Empirical and practical theoretical methods were used on 6 watersheds in central Ohio. The results showed that the extent of the meander pattern for all of the watersheds was well represented by the empirical streamway width equation. An analysis of flow and bed load transport in a compound twostage channel was performed for a series of different magnitude events that might occur during a 100 year period. The results showed that 1) floodplain width reduction, 2) entrenchment and 3) changes in flow regime each had a high potential to increase bed load transport and collectively changes in all these factors could result in a five to fifteen fold increase. The recommended approach is to establish setbacks that are a function of the meander belt width as calculated by an empirical equation that is based on the drainage area. Also, land uses within the setback zone should be restricted to uses that sustain or enhance the ecological function of the system and accommodate the stream in a state of dynamic equilibrium. Based on a previous study by the authors it is also recommended that storm water management strategies be used expressly to control bed load sediment transport rates.

Self-Sustaining Solutions for Streams, Wetlands, and Watersheds, 12-15, September 2004, 2004

ABSTRACT This study (1) evaluated how flood-peak discharges are associated with several common ap... more ABSTRACT This study (1) evaluated how flood-peak discharges are associated with several common approaches for determining the recurrence interval (return period) and annual frequency of storm events, and (2) analyzed and tested the United States Geologic Survey (USGS) rural and urban flood-peak discharge regression equations for Ohio to determine if they can provide effective estimations of peak discharges at lower recurrence intervals (less than 2 years) and using simple, practical data collection methods. The USGS equations were tested on 79 watersheds in Ohio with various drainage sizes. An analysis of measured discharge used annual series streamflow data from USGS gaging stations and related it to recurrence interval using the Weibull method. An analysis of predicted discharge involved solving the USGS equations and comparing the results to measured discharge values. This relationship was evaluated based on y = (1)x. Slope and intercept terms were evaluated for significance (alpha = 0.05) for each trend line equation. In general, on smaller watersheds (less than 35 mi2) the USGS rural and urban equations provided reasonably good estimates of measured discharge. On watersheds greater than 100 mi2, the USGS urban equation provided good estimates of measured discharge. Different methods of collecting data for the rural equation variables included the use of USGS 7.5-minute topographic quadrangle maps and Geographic Information Systems (GIS) technology. Comparing the two methods showed that for the watersheds used in this study, simple practical methods of data collection provided similar estimations of peak discharge to data gathered using GIS. Manipulating the coefficients in the urban equation through regression analysis provided even better estimates indicating that some modification to the current urban equation may be useful. The basin development factor (BDF) variable was not significant (alpha = 0.05) in the urban equation across all watersheds sizes and recurrence intervals suggesting that the watersheds used in the study may not be urbanized enough for it to be important in the equation. However, this variable is needed because it is the only indicator of urban development in the USGS equations.

21st Century Watershed Technology: Improving Water Quality and Environment Conference Proceedings, May 27-June 1, 2012, Bari, Italy, 2012

Self-Sustaining Solutions for Streams, Wetlands, and Watersheds, 12-15, September 2004, 2004

2011 Louisville, Kentucky, August 7 - August 10, 2011, 2011

ABSTRACT Much of the landscape in the Midwest region of the United States has been converted to a... more ABSTRACT Much of the landscape in the Midwest region of the United States has been converted to agricultural use and with this conversion has come greatly altered hydrologic functioning. Elimination of wetland storage and installation of subsurface drainage systems and agricultural ditches has caused water to drain from agricultural watersheds at accelerated rates. Agricultural fields, subsurface drainage, and a network of modified headwater systems now dominate the landscape in the Midwest region of the United States. These systems are often the main conduits that export sediment and nutrients downstream, but very little is known about how they function. Research by the authors has led to the modification of some trapezoidal agricultural ditches to two-stage geometries that are sized based on geomorphic concepts. Most of these innovative systems are located in Indiana, Michigan and Ohio. A procedure for sizing these systems has been developed by the authors. The main objective of the paper is to present details on how these systems have evolved since construction. The paper addresses issues that require further consideration. All systems that have been studied have been stable, exhibited small adjustments on the constructed floodplains (benches), and have required little or no maintenance. Also presented is a tool for evaluating the nitrate-nitrogen reduction potential of modifying channels to two-stage geometries that provide connection to floodplains and more bank storage. Preliminary results indicate that benches (small floodplains) should be located at elevations associated with about 25-35% of the 2-year discharge, and nitrate-nitrogen removal in systems with flooded width ratios of 4 to 5 times the bankfull width might be 5-20% of exports from fields if the treatment area (surface of the benches and inset channel) is 1%-2% of the watershed area.

2003, Las Vegas, NV July 27-30, 2003, 2003

... Jon Witter, Graduate Associate1 Anand Jayakaran, Graduate Associate1 ... In a study in the no... more ... Jon Witter, Graduate Associate1 Anand Jayakaran, Graduate Associate1 ... In a study in the northernRocky Mountains, Emmett and Wolman (2001) report RIs ranging from 1.5 to 1.7 years, while MacRae (1996) reports RIs of 1.6 to 10 years for a study in British Columbia. ...

Journal of Contaminant Hydrology, 2013

Journal of Contaminant Hydrology, 2011

Three-dimensional, coupled variably saturated flow and biogeochemical reactive transport modeling... more Three-dimensional, coupled variably saturated flow and biogeochemical reactive transport modeling of a 2008 in situ uranium bioremediation field experiment is used to better understand the interplay of transport and biogeochemical reactions controlling uranium behavior under pulsed acetate amendment, seasonal water table variation, spatially variable physical (hydraulic conductivity, porosity) and geochemical (reactive surface area) material properties. While the simulation of the 2008 Big Rusty acetate biostimulation field experiment in Rifle, Colorado was generally consistent with behaviors identified in previous field experiments at the Rifle IFRC site, the additional process and property detail provided several new insights. A principal conclusion from this work is that uranium bioreduction is most effective when acetate, in excess of the sulfate-reducing bacteria demand, is available to the metal-reducing bacteria. The inclusion of an initially small population of slow growing sulfate-reducing bacteria identified in proteomic analyses led to an additional source of Fe(II) from the dissolution of Fe(III) minerals promoted by biogenic sulfide. The falling water table during the experiment significantly reduced the saturated thickness of the aquifer and resulted in reactants and products, as well as unmitigated uranium, in the newly unsaturated vadose zone. High permeability sandy gravel structures resulted in locally high flow rates in the vicinity of injection wells that increased acetate dilution. In downgradient locations, these structures created preferential flow paths for acetate delivery that enhanced local zones of TEAP reactivity and subsidiary reactions. Conversely, smaller transport rates associated with the lower permeability lithofacies (e.g., fine) and vadose zone were shown to limit acetate access and reaction. Once accessed by acetate, however, these same zones limited subsequent acetate dilution and provided longer residence times that resulted in higher concentrations of TEAP reaction products when terminal electron donors and acceptors were not limiting. Finally, facies-based porosity and reactive surface area variations were shown to affect aqueous uranium concentration distributions with localized effects of the fine lithofacies having the largest impact on U(VI) surface complexation. The ability to model the comprehensive biogeochemical reaction network, and spatially and temporally variable processes, properties, and conditions controlling uranium behavior during engineered bioremediation in the naturally complex Rifle IFRC subsurface system required a subsurface simulator that could use the large memory and computational performance of a massively parallel computer. In this case, the eSTOMP simulator, operating on 128 processor cores for 12 h, was used to simulate the 110-day field experiment and 50 days of post-biostimulation behavior.

Environmental Monitoring and Assessment, 2009

In this paper, we evaluate relationships between in-stream habitat, water chemistry, spatial dist... more In this paper, we evaluate relationships between in-stream habitat, water chemistry, spatial distribution within a predominantly agricultural Midwestern watershed and geomorphic features and fish assemblage attributes and abundances. Our specific objectives were to: (1) identify and quantify key environmental variables at reach and system wide (watershed) scales; and (2) evaluate the relative influence of those environmental factors in structuring and explaining fish assemblage attributes at reach scales to help prioritize stream monitoring efforts and better incorporate all factors that influence aquatic biology in watershed management programs. The original combined data set consisted of 31 variables measured at 32 sites, which was reduced to 9 variables through correlation and linear regression analysis: stream order, percent wooded riparian zone, drainage area, in-stream cover quality, substrate quality, gradient, cross-sectional area, width of the flood prone area, and average substrate size. Canonical correspondence analysis (CCA) and variance partitioning were used to relate environmental variables to fish species abundance and assemblage attributes. Fish assemblages and abundances were explained best by stream size, gradient, substrate size and quality, and percent wooded riparian zone. Further data are needed to investigate why water chemistry variables had insignificant relationships with IBI scores. Results suggest that more quantifiable variables and consideration of spatial location of a stream reach within a watershed system should be standard data incorporated into stream monitoring programs to identify impairments that, while biologically limiting, are not fully captured or elucidated using current bioassessment methods.

Ecological Engineering, 2011

... Rebecca M. Gorney a , E-mail The Corresponding Author , Dawn R. Ferris b , E-mail The Corresp... more ... Rebecca M. Gorney a , E-mail The Corresponding Author , Dawn R. Ferris b , E-mail The Corresponding Author , Andy D. Ward c ... with the bankfull discharges that move the measured median bed particle size ([Knighton, 1993], [Ward and Trimble, 2004] and [Wilcock, 2001]). ...

Self-Sustaining Solutions for Streams, Wetlands, and Watersheds, 12-15, September 2004, 2004

... 25 10162 22495 10148 546 247 246 50 11809 30121 11141 663 260 274 100 13456 37488 12148 786 2... more ... 25 10162 22495 10148 546 247 246 50 11809 30121 11141 663 260 274 100 13456 37488 12148 786 282 301 Ditch Geometry and Two-Stage Design A survey of a 2100 ft length of ditch was performed by Joe Draper, Erick Powell, and Andy Ward on July 17, 2003. ...

2002 Chicago, IL July 28-31, 2002, 2002

The objectives of the study were: (1) to evaluate the ability of an empirically based equation to... more The objectives of the study were: (1) to evaluate the ability of an empirically based equation to predict the streamway width required to allow a stream to self-adjust its meander pattern; (2) to evaluate the influence of urbanization, floodplain width, and incision on bed load transport, the size of particle moved at incipient motion at flows approximating the effective discharge, and flood stage for the 100 year recurrence interval event; and to determine if knowledge obtained from Objectives 1 and 2 could b e used to develop stream setback guidelines that would help avoid channel instability problems typically associated with urbanization. Empirical and practical theoretical methods were used on 6 watersheds in central Ohio. The results showed that the extent of the meander pattern for all of the watersheds was well represented by the empirical streamway width equation. An analysis of flow and bed load transport in a compound twostage channel was performed for a series of different magnitude events that might occur during a 100 year period. The results showed that 1) floodplain width reduction, 2) entrenchment and 3) changes in flow regime each had a high potential to increase bed load transport and collectively changes in all these factors could result in a five to fifteen fold increase. The recommended approach is to establish setbacks that are a function of the meander belt width as calculated by an empirical equation that is based on the drainage area. Also, land uses within the setback zone should be restricted to uses that sustain or enhance the ecological function of the system and accommodate the stream in a state of dynamic equilibrium. Based on a previous study by the authors it is also recommended that storm water management strategies be used expressly to control bed load sediment transport rates.

Self-Sustaining Solutions for Streams, Wetlands, and Watersheds, 12-15, September 2004, 2004

... 25 10162 22495 10148 546 247 246 50 11809 30121 11141 663 260 274 100 13456 37488 12148 786 2... more ... 25 10162 22495 10148 546 247 246 50 11809 30121 11141 663 260 274 100 13456 37488 12148 786 282 301 Ditch Geometry and Two-Stage Design A survey of a 2100 ft length of ditch was performed by Joe Draper, Erick Powell, and Andy Ward on July 17, 2003. ...

Self-Sustaining Solutions for Streams, Wetlands, and Watersheds, 12-15, September 2004, 2004

... 25 10162 22495 10148 546 247 246 50 11809 30121 11141 663 260 274 100 13456 37488 12148 786 2... more ... 25 10162 22495 10148 546 247 246 50 11809 30121 11141 663 260 274 100 13456 37488 12148 786 282 301 Ditch Geometry and Two-Stage Design A survey of a 2100 ft length of ditch was performed by Joe Draper, Erick Powell, and Andy Ward on July 17, 2003. ...

The objectives of the study were: (1) to evaluate the ability of an empirically based equation to... more The objectives of the study were: (1) to evaluate the ability of an empirically based equation to predict the streamway width required to allow a stream to self-adjust its meander pattern; (2) to evaluate the influence of urbanization, floodplain width, and incision on bed load transport, the size of particle moved at incipient motion at flows approximating the effective discharge, and flood stage for the 100 year recurrence interval event; and to determine if knowledge obtained from Objectives 1 and 2 could b e used to develop stream setback guidelines that would help avoid channel instability problems typically associated with urbanization. Empirical and practical theoretical methods were used on 6 watersheds in central Ohio. The results showed that the extent of the meander pattern for all of the watersheds was well represented by the empirical streamway width equation. An analysis of flow and bed load transport in a compound twostage channel was performed for a series of different magnitude events that might occur during a 100 year period. The results showed that 1) floodplain width reduction, 2) entrenchment and 3) changes in flow regime each had a high potential to increase bed load transport and collectively changes in all these factors could result in a five to fifteen fold increase. The recommended approach is to establish setbacks that are a function of the meander belt width as calculated by an empirical equation that is based on the drainage area. Also, land uses within the setback zone should be restricted to uses that sustain or enhance the ecological function of the system and accommodate the stream in a state of dynamic equilibrium. Based on a previous study by the authors it is also recommended that storm water management strategies be used expressly to control bed load sediment transport rates.

Self-Sustaining Solutions for Streams, Wetlands, and Watersheds, 12-15, September 2004, 2004

ABSTRACT This study (1) evaluated how flood-peak discharges are associated with several common ap... more ABSTRACT This study (1) evaluated how flood-peak discharges are associated with several common approaches for determining the recurrence interval (return period) and annual frequency of storm events, and (2) analyzed and tested the United States Geologic Survey (USGS) rural and urban flood-peak discharge regression equations for Ohio to determine if they can provide effective estimations of peak discharges at lower recurrence intervals (less than 2 years) and using simple, practical data collection methods. The USGS equations were tested on 79 watersheds in Ohio with various drainage sizes. An analysis of measured discharge used annual series streamflow data from USGS gaging stations and related it to recurrence interval using the Weibull method. An analysis of predicted discharge involved solving the USGS equations and comparing the results to measured discharge values. This relationship was evaluated based on y = (1)x. Slope and intercept terms were evaluated for significance (alpha = 0.05) for each trend line equation. In general, on smaller watersheds (less than 35 mi2) the USGS rural and urban equations provided reasonably good estimates of measured discharge. On watersheds greater than 100 mi2, the USGS urban equation provided good estimates of measured discharge. Different methods of collecting data for the rural equation variables included the use of USGS 7.5-minute topographic quadrangle maps and Geographic Information Systems (GIS) technology. Comparing the two methods showed that for the watersheds used in this study, simple practical methods of data collection provided similar estimations of peak discharge to data gathered using GIS. Manipulating the coefficients in the urban equation through regression analysis provided even better estimates indicating that some modification to the current urban equation may be useful. The basin development factor (BDF) variable was not significant (alpha = 0.05) in the urban equation across all watersheds sizes and recurrence intervals suggesting that the watersheds used in the study may not be urbanized enough for it to be important in the equation. However, this variable is needed because it is the only indicator of urban development in the USGS equations.

21st Century Watershed Technology: Improving Water Quality and Environment Conference Proceedings, May 27-June 1, 2012, Bari, Italy, 2012

Self-Sustaining Solutions for Streams, Wetlands, and Watersheds, 12-15, September 2004, 2004

2011 Louisville, Kentucky, August 7 - August 10, 2011, 2011

ABSTRACT Much of the landscape in the Midwest region of the United States has been converted to a... more ABSTRACT Much of the landscape in the Midwest region of the United States has been converted to agricultural use and with this conversion has come greatly altered hydrologic functioning. Elimination of wetland storage and installation of subsurface drainage systems and agricultural ditches has caused water to drain from agricultural watersheds at accelerated rates. Agricultural fields, subsurface drainage, and a network of modified headwater systems now dominate the landscape in the Midwest region of the United States. These systems are often the main conduits that export sediment and nutrients downstream, but very little is known about how they function. Research by the authors has led to the modification of some trapezoidal agricultural ditches to two-stage geometries that are sized based on geomorphic concepts. Most of these innovative systems are located in Indiana, Michigan and Ohio. A procedure for sizing these systems has been developed by the authors. The main objective of the paper is to present details on how these systems have evolved since construction. The paper addresses issues that require further consideration. All systems that have been studied have been stable, exhibited small adjustments on the constructed floodplains (benches), and have required little or no maintenance. Also presented is a tool for evaluating the nitrate-nitrogen reduction potential of modifying channels to two-stage geometries that provide connection to floodplains and more bank storage. Preliminary results indicate that benches (small floodplains) should be located at elevations associated with about 25-35% of the 2-year discharge, and nitrate-nitrogen removal in systems with flooded width ratios of 4 to 5 times the bankfull width might be 5-20% of exports from fields if the treatment area (surface of the benches and inset channel) is 1%-2% of the watershed area.

2003, Las Vegas, NV July 27-30, 2003, 2003

... Jon Witter, Graduate Associate1 Anand Jayakaran, Graduate Associate1 ... In a study in the no... more ... Jon Witter, Graduate Associate1 Anand Jayakaran, Graduate Associate1 ... In a study in the northernRocky Mountains, Emmett and Wolman (2001) report RIs ranging from 1.5 to 1.7 years, while MacRae (1996) reports RIs of 1.6 to 10 years for a study in British Columbia. ...

Journal of Contaminant Hydrology, 2013

Journal of Contaminant Hydrology, 2011

Three-dimensional, coupled variably saturated flow and biogeochemical reactive transport modeling... more Three-dimensional, coupled variably saturated flow and biogeochemical reactive transport modeling of a 2008 in situ uranium bioremediation field experiment is used to better understand the interplay of transport and biogeochemical reactions controlling uranium behavior under pulsed acetate amendment, seasonal water table variation, spatially variable physical (hydraulic conductivity, porosity) and geochemical (reactive surface area) material properties. While the simulation of the 2008 Big Rusty acetate biostimulation field experiment in Rifle, Colorado was generally consistent with behaviors identified in previous field experiments at the Rifle IFRC site, the additional process and property detail provided several new insights. A principal conclusion from this work is that uranium bioreduction is most effective when acetate, in excess of the sulfate-reducing bacteria demand, is available to the metal-reducing bacteria. The inclusion of an initially small population of slow growing sulfate-reducing bacteria identified in proteomic analyses led to an additional source of Fe(II) from the dissolution of Fe(III) minerals promoted by biogenic sulfide. The falling water table during the experiment significantly reduced the saturated thickness of the aquifer and resulted in reactants and products, as well as unmitigated uranium, in the newly unsaturated vadose zone. High permeability sandy gravel structures resulted in locally high flow rates in the vicinity of injection wells that increased acetate dilution. In downgradient locations, these structures created preferential flow paths for acetate delivery that enhanced local zones of TEAP reactivity and subsidiary reactions. Conversely, smaller transport rates associated with the lower permeability lithofacies (e.g., fine) and vadose zone were shown to limit acetate access and reaction. Once accessed by acetate, however, these same zones limited subsequent acetate dilution and provided longer residence times that resulted in higher concentrations of TEAP reaction products when terminal electron donors and acceptors were not limiting. Finally, facies-based porosity and reactive surface area variations were shown to affect aqueous uranium concentration distributions with localized effects of the fine lithofacies having the largest impact on U(VI) surface complexation. The ability to model the comprehensive biogeochemical reaction network, and spatially and temporally variable processes, properties, and conditions controlling uranium behavior during engineered bioremediation in the naturally complex Rifle IFRC subsurface system required a subsurface simulator that could use the large memory and computational performance of a massively parallel computer. In this case, the eSTOMP simulator, operating on 128 processor cores for 12 h, was used to simulate the 110-day field experiment and 50 days of post-biostimulation behavior.

Environmental Monitoring and Assessment, 2009

In this paper, we evaluate relationships between in-stream habitat, water chemistry, spatial dist... more In this paper, we evaluate relationships between in-stream habitat, water chemistry, spatial distribution within a predominantly agricultural Midwestern watershed and geomorphic features and fish assemblage attributes and abundances. Our specific objectives were to: (1) identify and quantify key environmental variables at reach and system wide (watershed) scales; and (2) evaluate the relative influence of those environmental factors in structuring and explaining fish assemblage attributes at reach scales to help prioritize stream monitoring efforts and better incorporate all factors that influence aquatic biology in watershed management programs. The original combined data set consisted of 31 variables measured at 32 sites, which was reduced to 9 variables through correlation and linear regression analysis: stream order, percent wooded riparian zone, drainage area, in-stream cover quality, substrate quality, gradient, cross-sectional area, width of the flood prone area, and average substrate size. Canonical correspondence analysis (CCA) and variance partitioning were used to relate environmental variables to fish species abundance and assemblage attributes. Fish assemblages and abundances were explained best by stream size, gradient, substrate size and quality, and percent wooded riparian zone. Further data are needed to investigate why water chemistry variables had insignificant relationships with IBI scores. Results suggest that more quantifiable variables and consideration of spatial location of a stream reach within a watershed system should be standard data incorporated into stream monitoring programs to identify impairments that, while biologically limiting, are not fully captured or elucidated using current bioassessment methods.

Ecological Engineering, 2011

... Rebecca M. Gorney a , E-mail The Corresponding Author , Dawn R. Ferris b , E-mail The Corresp... more ... Rebecca M. Gorney a , E-mail The Corresponding Author , Dawn R. Ferris b , E-mail The Corresponding Author , Andy D. Ward c ... with the bankfull discharges that move the measured median bed particle size ([Knighton, 1993], [Ward and Trimble, 2004] and [Wilcock, 2001]). ...