5/18/2015  |   13:30 - 13:45   |  101B

IOWA FLOOD CENTER AND IOWA NUTRIENT RESEARCH CENTER: CRITICAL RESOURCES FOR IMPROVED FLOOD AND NUTRIENT MONITORING, MODELING AND FORECASTING The talk will provide an overview of two programs at IIHR – Hydroscience and Engineering at the University of Iowa. The presentation will focus on research, technology development and community outreach programs of the Iowa Flood Center (IFC) and Iowa Nutrient Research Center (INRC). The talk will describe IFC’s stream monitoring, modeling and forecast systems, as well as, the Iowa Flood Information System, an advanced online web portal used to communicate complex, flood-related data to citizens, communities, emergency managers and state/federal agencies interested in understanding the natural evolution of floods. Research is focused on developing improved instrumentation for flood monitoring, advanced numerical models for flood forecasting, and a strong public outreach and education program. Similarly, the talk will highlight INRC’s stream water quality monitoring network, recent trends in nutrient concentrations and loads in Iowa and advanced watershed scale models to predict impact of hydrologic events on the fate and transport of nutrients. Originating after the 2008 floods, the Iowa Flood Center is an academic-based research center focused on improving flood readiness and long-term resiliency to flood hazards. Likewise, the Iowa Nutrient Research Center was established by the Iowa Legislature as a Regents-based academic research center combining research strengths at Iowa State University, The University of Iowa and Northern Iowa University.

Larry Weber (Primary Presenter/Author), University of Iowa, Director, IIHR – Hydroscience and Engineering, larry-weber@uiowa.edu;

5/18/2015  |   13:45 - 14:00   |  101B

IN-STREAM NITROGEN PROCESSING AND DILUTION IN AN AGRICULTURAL STREAM NETWORK The interaction of agricultural fertilizer use by humans and extremes in drought and flood conditions in 2012-2013 set up conditions for a natural experiment on watershed-scale nutrient dynamics. The region-wide drought in 2012 left surface soils disconnected from stream networks and restricted nutrient use by crops, resulting in an unusually large nitrogen pool in soil columns through the winter. When wet conditions returned to the Midwest in 2013, the unused fertilizer was mobilized, resulting in a six-week period of extremely high in-stream nutrient concentrations. This study analyses three synoptic samples from the Iowa-Cedar River Basin in 2013 to quantify patterns in nitrogen dynamics. We use multiple conservative ions as tracers to estimate dilution by lateral inflows. We also estimate nutrient spiraling metrics by treating the fertilizer pulse as a constant rate nutrient addition across the watershed—a scale on which these processes are increasingly modeled numerically, but on which standard nutrient addition experiments are not feasible. Results of this study compare patterns in dilution and uptake across spatial and temporal scales, and bound feasible explanations for each reach of the network.

Adam Ward (POC,Primary Presenter), Indiana University, adamward@indiana.edu;


Kara Prior (Co-Presenter/Co-Author), University of Iowa, kara-prior@uiowa.edu;


Caroline A. Davis (Co-Presenter/Co-Author), University of Iowa, caroline-davis@uiowa.edu;


Amy Burgin (Co-Presenter/Co-Author), University of Kansas, burginam@ku.edu;


Terrance D. Loecke (Co-Presenter/Co-Author), University of Kansas, loeckete@gmail.com;


Diego Riveros-Iregui (Co-Presenter/Co-Author), University of North Carolina, diegori@unc.edu;


Douglas Schnoebelen (Co-Presenter/Co-Author), University of Iowa, douglas-schnoebelen@uiowa.edu;


Craig Just (Co-Presenter/Co-Author), University of Iowa, craig-just@uiowa.edu;


Steven Thomas (Co-Presenter/Co-Author), University of Alabama, sathomas16@ua.edu;


Larry Weber (Co-Presenter/Co-Author), University of Iowa, Director, IIHR – Hydroscience and Engineering, larry-weber@uiowa.edu;


Martin St. Clair (Co-Presenter/Co-Author), Coe College, mstclair@coe.edu;


Scott Spak (Co-Presenter/Co-Author), University of Iowa, scott-spak@uiowa.edu;


Kajsa Dalrymple (Co-Presenter/Co-Author), University of Iowa, kajsa-dalrymple@uiowa.edu;

5/18/2015  |   14:00 - 14:15   |  101B

IN-STREAM NITROGEN PROCESSING AND DILUTION IN AN AGRICULTURAL STREAM NETWORK The interaction of agricultural fertilizer use by humans and extremes in drought and flood conditions in 2012-2013 set up conditions for a natural experiment on watershed-scale nutrient dynamics. The region-wide drought in 2012 left surface soils disconnected from stream networks and restricted nutrient use by crops, resulting in an unusually large nitrogen pool in soil columns through the winter. When wet conditions returned to the Midwest in 2013, the unused fertilizer was mobilized, resulting in a six-week period of extremely high in-stream nutrient concentrations. This study analyses three synoptic samples from the Iowa-Cedar River Basin in 2013 to quantify patterns in nitrogen dynamics. We use multiple conservative ions as tracers to estimate dilution by lateral inflows. We also estimate nutrient spiraling metrics by treating the fertilizer pulse as a constant rate nutrient addition across the watershed—a scale on which these processes are increasingly modeled numerically, but on which standard nutrient addition experiments are not feasible. Results of this study compare patterns in dilution and uptake across spatial and temporal scales, and bound feasible explanations for each reach of the network.

Adam Ward (POC,Primary Presenter), Indiana University, adamward@indiana.edu;


Kara Prior (Co-Presenter/Co-Author), University of Iowa, kara-prior@uiowa.edu;


Caroline A. Davis (Co-Presenter/Co-Author), University of Iowa, caroline-davis@uiowa.edu;


Amy Burgin (Co-Presenter/Co-Author), University of Kansas, burginam@ku.edu;


Terrance D. Loecke (Co-Presenter/Co-Author), University of Kansas, loeckete@gmail.com;


Diego Riveros-Iregui (Co-Presenter/Co-Author), University of North Carolina, diegori@unc.edu;


Douglas Schnoebelen (Co-Presenter/Co-Author), University of Iowa, douglas-schnoebelen@uiowa.edu;


Craig Just (Co-Presenter/Co-Author), University of Iowa, craig-just@uiowa.edu;


Steven Thomas (Co-Presenter/Co-Author), University of Alabama, sathomas16@ua.edu;


Larry Weber (Co-Presenter/Co-Author), University of Iowa, Director, IIHR – Hydroscience and Engineering, larry-weber@uiowa.edu;


Martin St. Clair (Co-Presenter/Co-Author), Coe College, mstclair@coe.edu;


Scott Spak (Co-Presenter/Co-Author), University of Iowa, scott-spak@uiowa.edu;


Kajsa Dalrymple (Co-Presenter/Co-Author), University of Iowa, kajsa-dalrymple@uiowa.edu;

5/18/2015  |   14:15 - 14:30   |  101B

COMBINED EFFECTS OF HYPORHEIC METABOLISM & POREWATER FLOW ON REACH-SCALE NUTRIENT UPTAKE: DO CONSERVATIVE TRACERS CAPTURE DISTRIBUTIONS OF HYPORHEIC METABOLISM? Co-injections of conservative tracers and nutrients are commonly used to assess net reach-scale nutrient transformation rates and benthic/hyporheic uptake parameters. However, little information is available on spatial patterns of metabolism in the benthic and hyporheic regions. We used numerical simulations to explore the effects of localized metabolism on estimates of reach-scale nutrient uptake rates. Metabolism locally depletes nutrient concentrations relative to conservative tracers, causing their concentration profiles of injected nutrients and conservative tracers to diverge. At slow rates of hyporheic exchange relative to rates of metabolism, overall hyporheic nutrient uptake is limited by delivery from the stream, and effective reach-scale nutrient uptake parameters will be controlled by the hyporheic exchange rate. At high rates of hyporheic exchange, the injected tracer can propagate beyond regions of high microbial activity, which commonly occur near the streambed surface. In this case, the injected tracer may not adequately capture timescales of nutrient replenishment in the most bioactive regions (periphyton, biofilms). We will show how both processes alter the relationship between local- and reach-scale biogeochemical transformation rates.

Aaron Packman (Primary Presenter/Author), Northwestern University, a-packman@northwestern.edu;


Angang Li (Co-Presenter/Co-Author), Northwestern University, angang-li@u.northwestern.edu;


Antoine Aubeneau (Co-Presenter/Co-Author), Purdue University, aubeneau@gmail.com;

5/18/2015  |   14:30 - 14:45   |  101B

COMBINED EFFECTS OF HYPORHEIC METABOLISM & POREWATER FLOW ON REACH-SCALE NUTRIENT UPTAKE: DO CONSERVATIVE TRACERS CAPTURE DISTRIBUTIONS OF HYPORHEIC METABOLISM? Co-injections of conservative tracers and nutrients are commonly used to assess net reach-scale nutrient transformation rates and benthic/hyporheic uptake parameters. However, little information is available on spatial patterns of metabolism in the benthic and hyporheic regions. We used numerical simulations to explore the effects of localized metabolism on estimates of reach-scale nutrient uptake rates. Metabolism locally depletes nutrient concentrations relative to conservative tracers, causing their concentration profiles of injected nutrients and conservative tracers to diverge. At slow rates of hyporheic exchange relative to rates of metabolism, overall hyporheic nutrient uptake is limited by delivery from the stream, and effective reach-scale nutrient uptake parameters will be controlled by the hyporheic exchange rate. At high rates of hyporheic exchange, the injected tracer can propagate beyond regions of high microbial activity, which commonly occur near the streambed surface. In this case, the injected tracer may not adequately capture timescales of nutrient replenishment in the most bioactive regions (periphyton, biofilms). We will show how both processes alter the relationship between local- and reach-scale biogeochemical transformation rates.

Aaron Packman (Primary Presenter/Author), Northwestern University, a-packman@northwestern.edu;


Angang Li (Co-Presenter/Co-Author), Northwestern University, angang-li@u.northwestern.edu;


Antoine Aubeneau (Co-Presenter/Co-Author), Purdue University, aubeneau@gmail.com;

5/18/2015  |   14:45 - 15:00   |  101B

SIZE MATTERS: THE EFFECT OF SUBSTRATE PARTICLE SIZE ON BENTHIC AMMONIUM AND PHOSPHATE UPTAKE RATES IN HIGH LATITUDE STREAMS Aquatic reaction rates, such as ammonium and phosphate uptake, are commonly scaled to a projected area, which normalizes observations relative to a square meter of stream bottom. However, streambeds are not planar surfaces and the total surface area available for interactions is much greater than the projected area, depending on the size, distribution, and depth of sediments. We compared projected and total surface area normalized uptake rates of four homogeneous substrate treatment classes sorted from native river sediments (D₅₀ particle size = 13, 31, 51, 84mm). Equal volumes of each treatment were colonized for five weeks in riffle and run habitats and collected for analysis in temperature controlled recirculating chambers (n=46). As anticipated, nitrogen and phosphorus uptake rates normalized using projected area decreased as sediment size increased. In contrast, uptake rates that were normalized using total substrate area were lower and tended to increase with increasing particle size. The significant interactions observed between substrate size and uptake has implications for predicting reaction rates in streams, especially in systems where substrate size is typically a function of location in the network.

Samuel P. Parker (Primary Presenter/Author), University of Vermont, samuel.parker@uvm.edu;


William Breck Bowden (Co-Presenter/Co-Author), University of Vermont, breck.bowden@uvm.edu;


Kyle A. Arndt (Co-Presenter/Co-Author), AECOM Corporation, kyle.arndt@aecom.com;


Joshua P. Benes (Co-Presenter/Co-Author), University of Vermont, joshua.benes@uvm.edu;


Derrick G. Jent (Co-Presenter/Co-Author), Murray State University, djent@murraystate.edu;


Courtney D. Giles (Co-Presenter/Co-Author), James Hutton Institute, courtney.giles@hutton.ac.uk;


Michael Flinn (Co-Presenter/Co-Author), Murray State University, mflinn@murraystate.edu;