Category: Statewide

Improved watershed modeling, uncertainty analysis and statistical techniques for TMDLs have been identified as immediate TMDL science needs by the National Research Council (US EPA 2002). Recently approved sediment TMDLs in Iowa use versions of the Universal Soil Loss Equation (USLE) with conservation input to account for uncertainty. The uncertainty associated with these USLE estimates cannot be explicitly quantified and the margin of safety (MOS) required by the TMDL program is considered to be implicit in the watershed modeling process. This project proposes to test the following hypothesis: The uncertainty associated with sediment TMDLs can be quantified by applying the process-based Water Erosion Prediction Project model (WEPP) and an explicit computation of the margin of safety (MOS).

The quality and quantity of groundwater resources in Iowa are a growing concern because of increased pressures on quantity and concerns about contamination. Interactions between land management, groundwater, and surface water are conceptually well understood but the impact of temporal shifts on groundwater and surface water are largely unknown. Groundwater and streamwater quality are of particular concern in cities such as Ames because of their reliance on groundwater as a water supply. Recent monitoring near College Creek in Ames identified nitrate in groundwater at two of four transects and significant total P and SRP concentrations present in all 12 wells and in streamwater. Recent groundwater modeling of the Ames aquifer suggests direct interaction between surface water transported through tributaries running through the city and the Ames aquifer. Because most streams that enter the alluvium of Squaw Creek and South Skunk River becoming losing streams at that point, contaminants in the streams will impact the city’s water supply. Thus, efforts to prevent contaminants from getting to streams in headwater areas are necessary to protect groundwater quality downstream. Those responsible for the contaminant loading become as important as the presence of the contaminants themselves. This research proposes the addition of a strongly integrative groundwater-streamwater component to an ongoing urban stormwater research/non-point source pollution research and stream stabilization effort on College Creek in Ames. Our proposal occurs at an interesting and exciting time for College Creek and the Ames community. The City of Ames is partnering with ISU researchers whose work with water resources in the community are supported by multiple agencies and institutions. The City also committed $291,540 of its operating budget over the next three years to match an IWIRB grant they were awarded for College Creek stream stabilization and riparian enhancement. As this momentum for addressing non-point source pollution grows, it is also understood that only a very limited amount of research has been dedicated to exploring groundwater from the perspective of the urban residentthe group likely responsible for much of the contaminant loading occurring in headwater areas. This proposal includes an innovative community-based education based on biophysical and social investigations of the urban groundwater-streamwater system at the neighborhood scale. We focus specifically on interactions between land management, groundwater, soil water and streamwater within the urban residential landscape. Monitoring of a nested well site adjacent to College Creek in Ames is accompanied by simultaneous investigation of groundwater perceptions and technical understanding among a statically representative sample of urban, riparian landowners. Research activities are organized to utilize the results from each component to inform the others. Early monitoring results are utilized to develop a social assessment tool to characterize the perceptions & misconceptions residents hold concerning local hydrologic processes and conditions. Social assessment results add landowner behavior data that, when integrated with monitoring and modeling, contribute to a greater understanding of nutrient movement between the landscape and hydrologic system. Finally, educational curriculum is developed to integrate both monitoring results as well as any lack of understanding or misconceptions identified during social assessment.

Excess sediment, phosphorus (P) and nitrogen (N) impair the majority of Iowa lakes and many streams also are impaired during some periods of the year. Most sediment and nutrients originate from agricultural fields or stream banks. A good potential for large-scale bioenergy production in Iowa is challenging researchers and nutrient management planners to develop crop and nutrient management systems to maximize production of feed, fuel, and fiber while utilizing soil and nutrient resources minimizing undesirable environmental impacts. Therefore, there is a need for studies of soil processes and nutrient loss on a field-plot scale that represent actual field conditions as much as possible focusing on bioenergy production and nutrient management systems likely to be adopted soon. The project will evaluate and compare systems that will still predominate for years to come in Iowa (such as corn and soybean for grain production) and new systems with likely adoption for bioenergy production (such as total or partial corn and perennial grass biomass harvest) managed with fertilizer or liquid swine manure. The study results will provide needed information about cropping and management systems for bioenergy production impacts on soil and water quality that can be compared to impacts from currently used systems. The proposed work will integrate efforts by scientists from the Department of Agronomy and the Department of Agricultural and Biosystems Engineering, by the ISU Research and Demonstration Farms System, a group of Northwest Iowa farmers (the Northwest Iowa Experimental Association), and seed funding by the IFLM program of IDALS. These contributions plus requested funding from the Iowa Water Center will be used to develop work during 2008 and 2009 at a runoff study site in Northwest Iowa and a tile-drainage study site in Central Iowa. We propose to study how crops, biomass harvesting systems, fertilizer and manure management practices, and selected soil properties relate to loss of sediment and various forms of N and P with surface runoff and subsurface tile drainage. The main objectives are (1) to determine dissolved reactive P, total dissolved P, algal-available P, total P, and total N concentrations and loads in surface runoff from corn production systems harvested for grain using different tillage and fertilizer or manure P management systems and from continuous corn harvested for grain and cornstalks and (2) to determine loss of nitrate, dissolved reactive P, and total dissolved P through subsurface tile drainage from crops for selected bioenergy production systems managed with fertilizer or manure N-P management systems. We will also analyze soil and harvested biomass for nutrient concentration and relate these results to treatment effects on N and P loss. Overall, the information from the study will be useful to establish new and improved environmentally oriented management guidelines and will provide useful information concerning impacts of anticipated land changes in the near future on export of nutrients to water resources.

Surface water from the Des Moines River is impaired by nitrate-nitrogen for drinking water use. Saylorville Reservoir is a 24.1 km2 impoundment of the Des Moines River located approximately 10 km north of the City of Des Moines. Monthly mean nitrate concentration data collected upstream and downstream of the reservoir for a 30-year period (1977-2006) are analyzed in this study. Our objective is to improve understanding of the reservoir effects on river nitrate concentrations. We hypothesize that monthly water quality downstream of the reservoir depends on the current monthly upstream water quality and its past lags. The dynamic relation is studied via a transfer function model that is shaped by reservoir characteristics such as surface area, volume, and discharge. Research results may used to better manage Saylorville Reservoir to mitigate nitrate concentrations in downstream receiving waters and forecast potential impairment to the Des Moines Water Works.

Runoff from open beef feedlots is a contributor of nutrients to the surface waters of Iowa. Currently, efforts are underway to improve the runoff control systems on open feedlot operations of all sizes. Both the Iowa Small Feedlot Team (comprised of ISU faculty and staff, Iowa DNR, and the NRCS) and the Iowa DNR expect vegetative treatment systems to be one of the lower cost, effective runoff control options that Iowa feed-lots can use to reduce beef feedlot runoff impacts on water quality. Improved understanding of the transport and fate of nitrogen and phosphorus within and from vegetative treatment systems is necessary to improve system design and to understand long term effectiveness of the treatment system. Currently, the Iowa State University – Vegetative Treatment Area model used to design and evaluate vegetative treatment system performance is based on runoff control system hydrology. Likewise, system performance has been evaluated based on effluent flow into and out of the treatment system. To improve the design capability of the Iowa State University – Vegetative Treatment Area model and performance of these runoff control systems, nutrient transport and fate needs to be considered. The objective of this proposal is to investigate the dynamics and transport of phosphorus and nitrogen applied to the vegetative treatment area. We propose to: • Measure phosphorus sorption isotherms on soils obtained from four vegetative treatment systems in Iowa • Determine nitrogen mineralization rates for feedlot runoff • Develop phosphorus budgets for four vegetative treatment systems in Iowa • Develop preliminary nitrogen budgets for four vegetative treatment systems in Iowa The deliverables produced as a result of this study will include: • Design guidance for sizing a vegetative treatment systems based on phosphorus loading • Design guidance for sizing a vegetative treatment systems based on nitrogen loading This data will be in direct support of the Iowa Small Feedlot Teams efforts to develop runoff control strategies for open beef feedlots. Data from this study will be used to develop guidance documents for appropriate VTS sizing and ultimately to add nitrogen and phosphorus simulation capabilities to the Iowa State University – Vegetative Treatment Area model. Developing these tools will provide consultants, NRCS, the Iowa DNR, and the Iowa Small Feedlot Team with the tools necessary to install more effective runoff control systems on open feedlots, protecting the waters of Iowa. The results of this study will be used as preliminary data to seek additional funding from the USDA – Agriculture and Food Research Initiative Competitive Grants Program to further evaluate the fate and transformations of nitrogen and phosphorus occurring in these systems. Future research topics that we will seek additional funding from USDA to investigate include; quantification of nitrogen leaching from the treatment area, measurement of gaseous nitrogen emissions from the treatment system, and measurement of the mineralization of organic phosphorus.

The sediment in transport within a stream is a complex mixture of eroded upland surface soils, collapsed channel bank material, and resuspended bed sediments. The proportion of sediment contributed from each primary source (i.e., uplands, banks, and bed) is affected by the relative rates of the dominant erosion processes occurring in a watershed. As we still deal with the daunting problem of water quality degradation by high sediment loads, the following question remains: “What are the contributions from each of the primary sources during a storm event and how do these contributions vary in space from the headwaters to the mouth of a watershed?” Upland erosion rates in Iowa watersheds are relatively high for the U.S. (e.g., Cruse et al., 2006). However, channel sources in some streams during extreme events can contribute up to 80% of the stream load (e.g., Wilson et al., 2008). The key objective of this research is to identify the major source(s) of sediment to the stream load of an anthropogenically altered watershed in SE Iowa, the Clear Creek, IA watershed (CCW). This information will provide better understanding of the relative roles of upland and channel erosion processes in the delivery of sediment to local streams. Identifying the major source(s) of sediment to the stream load will also allow for better focusing of remediation efforts to abate another predominant water quality concern in Iowa, namely high sediment-associated P loads. Transport and mixing of sediment-associated P in rivers often constitutes a high percentage of (23-61%) of the total annual P load (e.g., Lick, 2009). We propose to use established tracing techniques, such as the naturally occurring radionuclides, 7Be and 210Pbxs, for identifying the proportions of sediment derived from each primary source (i.e., uplands, banks, and bed) under different magnitude hydrologic events, including floods. In particular, 7Be has shown the unique ability to differentiate upland soils from stream bank and bed sediments (e.g., Wilson et al., 2008). 7Be is produced continuously in the atmosphere but delivered to the earth surface in high concentrations mainly during precipitation events. Moreover, 7Be does not remain long in the soil before decaying due to its relatively short half-life of only 53 days. Thus, there is a strong relationship between a single erosion event and high signatures of 7Be in the eroded upland soils. To meet our research goal, a comprehensive study is designed that takes advantage of existing monitoring and database infrastructure in the CCW. First, we will construct sediment rating curves (i.e. flow discharge vs. sediment flux curves) using existing in-situ, measuring instrumentation for flow discharges and sediment fluxes [Task 1]. We will partition the sediment sources corresponding to each event by analyzing the radionuclide activity of collected grab samples through gamma spectroscopy in the laboratory. The activities of the grab samples will be compared against the radionuclide activities of sediments extracted from the primary sources, namely, the uplands, channel banks, and stream bed. An established unmixing model (Fox and Papanicolaou, 2007) will be used to isolate the fraction of each primary source contributions in terms of mass (or volume) [Task 2]. The data from this study will be incorporated in the Clear Creek Digital Watershed and used for model verification and model refinement [Task 3]. These rare data will allow us to quantify for the first time the sediment fluxes from different sources under different hydrologic conditions and will lead to the refinement and extension of sediment rating curves applicable to most Midwestern agricultural watersheds. If we can quantify the dominant sediment source(s) in streams, we can identify the areas, which need BMPs to control sediment-bound P, and design our BMPs more efficiently. The results will be disseminated in EOS and the journal of Soil Water Conservation (JSWC). This study will support a Master’s level student and laboratory sediment analysis.

Problem: Urban watersheds are composed of a complicated spatial fabric and are influenced by a wide range of often competing economic, policy, and public interest drivers and constraints. With increased regulation of stormwater discharges taking place on a national basis, there are greater pressures on municipalities to develop effective urban stormwater management strategies. In addition, highlighted by recent events in Iowa, there is great interest in flooding and potential mechanisms for better managing the landscape, including urban areas, to improve hydrologic response and reduce damaging flooding events. To these ends, there is a great need for effective tools which can aid the design and execution of such strategies by identifying hot-spot areas contributing to excessive discharges and pollutants and to evaluate potential best management practices. Methods: This project will address urban hydrological problems in the first instance and year by developing processes for incorporating Light Detection and Ranging (LiDAR) elevation data into modeling processes using an industry-standard urban watershed model (WinSLAMM). Iowa is one of the first states in the country to have state-wide coverage of LiDAR data and this presents an opportunity to develop improved WinSLAMM modeling processes using LiDAR data. These processes will be initiated in the Dry Run Creek (an impaired waterway) watershed (85% of Cedar Falls) and then transferred to the Catfish Creek watershed which overlaps with large portions of Dubuque. In the event of second year funding, a new ArcGIS extension, called ArcWinSLAMM, will be developed. This extension will provide more efficient mechanisms for input parameterization of WinSLAMM and allow for easier visualization of modeled results. The extension will be developed with standard application development tools and will be made freely available. The development process will include beta testing by personnel with WinSLAMM modeling experience. In addition, training sessions for using the new ArcWinSLAMM extension will be provided at the end of the project. Objectives: The goals of the project include the development and demonstration of more effective WinSLAMM modeling processes utilizing LiDAR topography data in the Dry Run Creek and Catfish Creek watersheds, the development of a freely available ArcGIS extension which will improve efficiency and accuracy in WinSLAMM modeling, and technology transfer in the form of training and provision of the free extension. The project will lead to novel techniques and technologies, adoptable throughout the country, for addressing both water quality and quantity (flooding) issues in urban watersheds.

The sediment in transport within a stream is a complex mixture of eroded upland surface soils, collapsed channel bank material, and resuspended bed sediments. The proportion of sediment contributed from each primary source (i.e., uplands, banks, and bed) is affected by the relative rates of the dominant erosion processes occurring in a watershed. As we still deal with the daunting problem of water quality degradation by high sediment loads, the following question remains: What are the contributions from each of the primary sources during a storm event and how do these contributions vary in space from the headwaters to the mouth of a watershed? Upland erosion rates in Iowa watersheds are relatively high for the U.S. (e.g., Cruse et al., 2006). However, channel sources in some streams during extreme events can contribute up to 80% of the stream load (e.g., Wilson et al., 2008). The key objective of this research is to identify the major source(s) of sediment to the stream load of an anthropogenically altered watershed in SE Iowa, the Clear Creek, IA watershed (CCW). This information will provide better understanding of the relative roles of upland and channel erosion processes in the delivery of sediment to local streams. Identifying the major source(s) of sediment to the stream load will also allow for better focusing of remediation efforts to abate another predominant water quality concern in Iowa, namely high sediment-associated P loads. Transport and mixing of sediment-associated P in rivers often constitutes a high percentage of (23-61%) of the total annual P load (e.g., Lick, 2009). We propose to use established tracing techniques, such as the naturally occurring radionuclides, 7Be and 210Pbxs, for identifying the proportions of sediment derived from each primary source (i.e., uplands, banks, and bed) under different magnitude hydrologic events, including floods. In particular, 7Be has shown the unique ability to differentiate upland soils from stream bank and bed sediments (e.g., Wilson et al., 2008). 7Be is produced continuously in the atmosphere but delivered to the earth surface in high concentrations mainly during precipitation events. Moreover, 7Be does not remain long in the soil before decaying due to its relatively short half-life of only 53 days. Thus, there is a strong relationship between a single erosion event and high signatures of 7Be in the eroded upland soils. To meet our research goal, a comprehensive study is designed that takes advantage of existing monitoring and database infrastructure in the CCW. First, we will construct sediment rating curves (i.e. flow discharge vs. sediment flux curves) using existing in-situ, measuring instrumentation for flow discharges and sediment fluxes [Task 1]. We will partition the sediment sources corresponding to each event by analyzing the radionuclide activity of collected grab samples through gamma spectroscopy in the laboratory. The activities of the grab samples will be compared against the radionuclide activities of sediments extracted from the primary sources, namely, the uplands, channel banks, and stream bed. An established unmixing model (Fox and Papanicolaou, 2007) will be used to isolate the fraction of each primary source contributions in terms of mass (or volume) [Task 2]. The data from this study will be incorporated in the Clear Creek Digital Watershed and used for model verification and model refinement [Task 3]. These rare data will allow us to quantify for the first time the sediment fluxes from different sources under different hydrologic conditions and will lead to the refinement and extension of sediment rating curves applicable to most Midwestern agricultural watersheds. If we can quantify the dominant sediment source(s) in streams, we can identify the areas, which need BMPs to control sediment-bound P, and design our BMPs more efficiently. The results will be disseminated in EOS and the journal of Soil Water Conservation (JSWC). This study will support a Masters level student and laboratory sediment analysis.

A fast and reliable method for in situ monitoring of soil nitrate-nitrogen (NO3-N) concentration is vital for understanding and improvement of N management practices focused on reduction of NO3-N losses to ground and surface waters from agricultural systems. Conventional methods for soil or solution NO3-N measurement are destructive, time-consuming, costly, and impractical for large-scale or high-resolution monitoring. Hence, there is a need for development of a relatively cheap and reliable indirect measurement method that can continuously monitor NO3-N dynamic in situ. During the last several decades, the dielectric response of a medium has been intensively used to characterize its physical or chemical properties. Bulk soil permittivity has been used in environmental monitoring to estimate volumetric water content (VWC) and soil salinity. As a result, several methods and multiple instruments have been developed to measure soil dielectric response at MHz frequency. But very few studies have been conducted to estimate change in soil NO3-N concentration using the dielectric response measured at the same spectrum. Furthermore, most of the commercially available dielectric soil sensors, particularly capacitance type probes, provide a single value for permittivity, which can be adequate to estimate a single soil property. Using dielectric measurements at multiple frequencies can help to estimate several physical and chemical soil properties simultaneously. We propose to investigate the dielectric footprint of pore water NO3-N content on soil bulk permittivity measured at MHz range, which includes the operating frequency of most dielectric soil probes. Hence the goal of the project will be to evaluate the feasibility to estimate changes in pore water NO3-N concentration at different VWC from the dielectric measurements obtained at multiple frequencies at MHz range using the chemometric analyses.

Increasing energy demands, global warming and concerns about fossil fuel depletion has led to an increasing focus being placed on bioenergy crops in the US. Large scale land-use changes from a corn-soybean rotation to native perennial plants have the potential to significantly alter the regional water balance and nutrient dynamics in the Midwest region of the US. Since nutrient loads in the surface water bodies remain a major environmental problem in Iowa today, it is vital to understand how the shift in land-use patterns can affect the regional hydrological cycle and change nutrient transport processes. In earlier research carried out by the PI and collaborators at the Comparison of Biofuel Systems (COBS) research site near Ames, IA, significant differences were observed in the drainage volumes and drainage water quality parameters among different biofuel cropping systems. The mechanisms driving these differences remain largely unknown. Crop evapotranspiration (ET) is a dominant factor in water balance of any region, but data are not available for direct field measurements of ET for some field crops, especially for a mixed prairie stand. There is a need to quantify ET by direct field measurements to help quantify the regional hydrological cycles. It is also important to quantify how changes in cropping systems affect the regional patterns in order to improve the management of regional water quality problems. The goal of the proposed work is to quantify the field water balance components as affected by different biofuel cropping systems. Direct field measurements of ET by a chamber technique and by sap flow measurements coupled with soil moisture, drainage and water quality data will enable us to measure crop water use under different cropping systems. This will also help us to quantify the dominant components leading to differences in drainage volumes among different cropping systems. The data obtained will be used to evaluate a crop growth, hydrological, and water quality model (RZWQM) to provide a tool for investigating the implications of land-use changes on field, state, and regional hydrological scales under a variety of soil, climatic and cropping conditions.