Category: Statewide

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.

The Intergovernmental Panel on Climate Change (IPCC) has predicted that changes in climate patterns (higher temperatures, changes in extreme precipitation events, higher level of humidity) will adversely impact water quality. The Climate Change Impacts on Iowa 2010 report shows that during the last few decades Iowa’s climate experienced significant variability in precipitation patterns, exhibiting wetter springs and dryer falls, an increase in dew point humidity levels, higher nighttime minimum temperatures, and a higher number of frost-free days. Furthermore, more intense rainfall increases the surface water runoff and subsurface drainage, thus resulting in more sediment and nutrient pollution of Iowa streams. Given the implications of climate change and variability on water and soil quality, it is important for watershed managers, stakeholders, and policymakers to understand not only the effectiveness of individual conservation practices in improving water quality but also the cost effectiveness of watershed-level policy programs designed for the implementation of conservation practices. The effectiveness of five conservation practices in reducing nonpoint source pollution will be modeled using the Soil and Water Assessment Tool (SWAT) watershed-scale water quality model, and compared across different climate scenarios. This information, together with cost-related information, will be used to simulate the cost efficiency of a reverse auction program. These results can offer insights for watershed managers willing to implement a program for nutrient (nonpoint source pollution) reductions. This study will consider the cost-efficiency of reverse auction program designed for improving water quality in the Boone River Watershed (BRW).This is the first study designed to address the effects of climate variability on the cost effectiveness of conservation policy design for nutrients in Iowa. The results of this project are intended to be presented in a conference setting and published in a peer reviewed journal with a focus on environmental and policy issues.

Iowa is plagued by catastrophic natural hazards on a yearly basis, with the 2008 flood and the 2012 drought being two of the most recent extreme events affecting our state. Unfortunately, the question is not if, but when, the next extreme event will happen. There is little we can do to prevent flooding or droughts but we can improve our preparedness for these events. Improved readiness relies on the availability of information that would allow Iowans to make more informed decision about the most suitable water management strategy. The proposed work aims to develop a framework to provide monthly forecasts of discharge over Iowa with a lead time from one month up to one year. The availability of these forecasts would have major societal and economic impacts on hydrology and water resources management, agriculture, disaster forecasts and prevention, energy, finance and insurance, food security, policy-making and public authorities, and transportation. This proposal will advance our preparedness for flood and drought conditions over Iowa. Our approach follows in two phases: Phase I will focus on development of a forecasting system to provide monthly discharge values for one watershed in Iowa (Raccoon River at Van Meter). The methodology leverages on the use of statistical models to describe discharge from low to high flow. These models use rainfall as well as row crop production acreage (used as a proxy for the characterization of the impacts of agricultural practices) as inputs. Monthly rainfall forecasts will be based on one coupled ocean-atmosphere model, while the forecast of row crop production will be based on the value from the previous year (persistence forecast). The discharge forecast will have a lead time from one month up to one year. Phase II will build on the insights gained during Phase I. During this phase, we will consider a total of four coupled ocean-atmosphere models and examine alternative ways of combining them in order to provide an improved forecast of rainfall. The domain of interest for the rainfall analyses will be expanded to the entire State of Iowa. Moreover, the discharge forecast will include a larger number of watersheds reflecting different geology, agricultural practices and rainfall climatology. The methodologies build on analysis tools and data sets with which the PI and Co-PI have extensive experience, and will be developed further here to address the problem of forecasting discharge over Iowa. The results of the proposed work will provide basic information critical to improving the planning and development of adaptation strategies to mitigate future costs and disruptions arising from flood and drought conditions. The results and data from this project will be made available to federal and state agencies, including the U.S. Geological Survey, the U.S. Army Corps of Engineers, the Federal Emergency Management Agency, National Weather Service, and the Iowa Department of Natural Resources. Moreover, this information will be readily available to local stakeholders and users for their own use. The PI is part of the team of researchers at the Iowa Flood Center (IFC), and will leverage the tools and expertise provided by the IFC to make the results of the proposed work relevant and immediately and directly available to agencies and to the general public. Moreover, the dissemination of the results will be facilitated by means of outreach activities through the IFC and the Iowa Water Center.

Soil moisture is the reservoir of water that supports agriculture. Soil moisture also affects the amount and variability of precipitation and hence the occurrence of drought. Remote sensing satellites that observe near–surface soil moisture have recently been launched or will be launched in the near future. Before measurements of near–surface soil moisture made from space can be used to estimate the amount of water stored in the soil and improve weather and climate predictions, the quantitative value of the measurements must be known. My long–term goal is to contribute to the construction of a water balance model for Iowa consisting of atmospheric and land surface models along with a data assimilation scheme. This model would ingest real–time information regarding soil moisture, river levels, precipitation, and atmospheric conditions, in order to give the best estimate of current and future soil water conditions throughout the state. Ultimately this system could be used to monitor the evolution of soil moisture, and as a tool to test actions that could be taken to ameliorate the impacts of drought and future climate variability. My objective in this proposal is to contribute to the validation of near–surface soil moisture observations made by current and future satellite remote sensors in order to assess the quantitative value of these space–based observations. My central hypothesis is that satellite observations of near–surface soil moisture are valid as determined by point–based in–situ observations of soil moisture scaled to match the size of the satellite footprint. My rationale for this project is two–fold: the quantitative value of remotely–sensed near–surface soil moisture must be known before it can be used effectively; and the state of Iowa should seize this opportunity to benefit from these new satellite measurements. I have a unique competitive advantage to test my hypotheses because I am currently a team–member of the European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) mission, a satellite launched in late 2009 that is currently making near–surface soil moisture observations, and NASA’s Soil Moisture Active Passive (SMAP) mission, which will be launched in late 2014. My specific research objectives for this project are as follows. • Improve and then validate SMOS near–surface soil moisture observations in Iowa. • Initiate the validation of SMAP near–surface soil moisture observations in Iowa. The expected outcome of this project will be validated near–surface soil moisture observations that could be used by hydrologists and atmospheric scientists to estimate soil water storage and improve the prediction of weather and climate in Iowa. I will use professional relationships developed during this project to submit proposals to NASA that will support future research on SMAP mission observations and water cycle studies in Iowa. If we are successful at validating these new satellite soil moisture observations, Iowa scientists will have a unique opportunity to estimate current soil moisture reserves and better understand the conditions leading to drought and hence mitigate the impact of this type of natural disaster on the citizens of Iowa.

2015 was a record year for the occurrence of harmful algal blooms (HABs) on Iowa lakes. HABs are a nuisance and public health issue, producing toxins that affect the safety of people, pets, and livestock, and interfere with the public’s ability to use surface waters for recreation. This is a particularly troubling issue in Iowa, where years of excess nutrient (nitrogen and phosphorus) loading has been linked to the emergence of frequent HABs in Iowa. As HABs are often composed of cyanobacteria rather than eukaryotic algae, a persistent question is how the geochemical conditions in Iowa’s lakes might select for HAB-forming cyanobacteria. Nutrient loading has enhanced primary productivity and the deposition of organic carbon to lake sediments, resulting in anoxic sediments and bottom waters, which facilitate release of soluble iron from the sediments. Iron is an essential micronutrient, which is required in higher amounts by cyanobacteria as compared to eukaryotic algae, and even may be toxic to certain types of algae. The role of iron supplied under anoxic conditions in regulating photosynthetic activity is a topic already under investigation by the PI. This project proposes to track the abundance and availability of iron in the water column and sediments at Iowa’s Great Lakes, which encompass a shallow lake with severe HABs (East Lake Okoboji), and a deep lake with less severe HABs (West Lake Okoboji). Sediment cores and water column samples will be collected from the lakes and analyzed at the Iowa Lakeside Laboratory Regents Resource Center (ILLRRC) near Milford, IA and the PI’s lab at Iowa State University (ISU). The concentrations of iron and phosphorus will be determined in samples collected from different depths within the water column over the course of a summer season. We will profile cores immediately after collection with iron microelectrodes to determine the sedimentary iron flux. Finally, a fluorescence method will be developed to identify and quantify the major phytoplankton groups from the water column in order to test whether their identity and abundance is linked to iron bioavailability. The basic science of this proposal is to determine if iron availability is linked to higher cyanobacterial abundances, as this class of bacteria is invoked in HABs. However, if the availability of sedimentary iron is linked to HABs, the results will inform future monitoring strategies. Our results will help to determine if routine iron measurements would be useful in forecasting HABs. We will also develop protocols for quickly and easy assessing the phytoplankton composition in Iowa’s lakes, which could be used for future monitoring by state agencies, or in collaboration with teams of citizen scientists.

Nutrient enrichment is a critical issue affecting Iowa surface water bodies. The Upper Midwestern United States is heavily drained and subsurface drainage provides a direct pathway for nutrients to enter surface waters. Nitrogen is typically the focus of research on nutrients in drainage; however, current research has shown that drainage can be a significant source of phosphorous loading as well. The goal of the proposed project is to evaluate the impact of subsurface drainage on P concentrations in surface waters. Objectives of the study are (1) to determine intra-event contributions of different P pathways and (2) apply the ICECREAMDB phosphorous model to Iowa agricultural watersheds. ICECREAMDB is a graphical front-end for the ICECREAM model that also includes options to structure outputs. ICECREAMDB is a management oriented phosphorus loss model that quantifies runoff, erosion, and P losses at the field scale and has the capability to simulate phosphorus losses through drainage systems. Water quality monitoring and model simulations will be conducted on the Black Hawk Lake watershed located in Carroll and Sac counties in Iowa. The Black Hawk Lake watershed was selected for this study because its three unique monitoring locations allow comparison of overland surface flow to tile flow water quality. Results of the project include an intra-event analysis of total phosphorus and dissolved reactive phosphorus concentrations in grass waterway, surface runoff, and tile flow and testing of a new model for predicting phosphorous in tiles, ICECREAMDB, in the heavily drained Iowa landscape.

This project completes the final three months of a two year project. Soil moisture is the reservoir of water that supports agriculture. Soil moisture also affects the amount and variability of precipitation and hence the occurrence of drought. Remote sensing satellites that observe near–surface soil moisture have recently been launched or will be launched in the near future. Before measurements of near–surface soil moisture made from space can be used to estimate the amount of water stored in the soil and improve weather and climate predictions, the quantitative value of the measurements must be known. My long–term goal is to contribute to the construction of a water balance model for Iowa consisting of atmospheric and land surface models along with a data assimilation scheme. This model would ingest real–time information regarding soil moisture, river levels, precipitation, and atmospheric conditions, in order to give the best estimate of current and future soil water conditions throughout the state. Ultimately this system could be used to monitor the evolution of soil moisture, and as a tool to test actions that could be taken to ameliorate the impacts of drought and future climate variability. My objective in this proposal is to contribute to the validation of near–surface soil moisture observations made by current and future satellite remote sensors in order to assess the quantitative value of these space–based observations. My central hypothesis is that satellite observations of near–surface soil moisture are valid as determined by point–based in–situ observations of soil moisture scaled to match the size of the satellite footprint. My rationale for this project is two–fold: the quantitative value of remotely–sensed near–surface soil moisture must be known before it can be used effectively; and the state of Iowa should seize this opportunity to benefit from these new satellite measurements. My specific research objectives for this project are as follows: Improve and then validate SMOS near–surface soil moisture observations in Iowa; Initiate the validation of SMAP near–surface soil moisture observations in Iowa. The expected outcome of this project will be validated near–surface soil moisture observations that could be used by hydrologists and atmospheric scientists to estimate soil water storage and improve the prediction of weather and climate in Iowa. I will use professional relationships developed during this project to submit proposals to NASA that will support future research on SMAP mission observations and water cycle studies in Iowa. If we are successful at validating these new satellite soil moisture observations, Iowa scientists will have a unique opportunity to estimate current soil moisture reserves and better understand the conditions leading to drought and hence mitigate the impact of this type of natural disaster on the citizens of Iowa.

This study applies new approaches to understand the fate of soluble pollutants in the urban environment. Soil samples collected during warm season months as part of this field study compliment an existing effort to assess impacts of winter road maintenance on water quality by considering relationships between chlorides, soils and metals. The objective is to expand sampling and analysis from winter roadway runoff to also consider soil quality as a means of characterizing the fate and transport of soluble pollutants in winter road maintenance regimes; thus reducing water contamination potential from winter road maintenance activities. By sampling soils during warm- season months, data collected compliments winter runoff sampling and broadens the overall potential for data analysis. It expands the scope of an urban water quality monitoring project by incorporating warm-season soil analysis to quantify impacts from winter roadway runoff in two Eastern Iowa communities. By understanding the fate and transport of road salts from transportation systems, we gain further insight to environmental susceptibility to surface and groundwater contamination. As winter roadway runoff is diverted to infiltration-based stormwater management practices such as rain gardens and bioretention cells, potential for chloride contamination can increase. Metals are soluble in roadway runoff. Urban stormwater management practices for sediment and solids removal may perform poorly for treating such soluble pollutants. Results will verify urban watershed modeling tools implemented in project’s initial assessment phase, and determine needs for further analysis, data collection and scalability. Results will also inform local policy and practice regarding water quality concerns from road salts.

Nitrate contamination from agriculture is a major water-quality problem in Iowa and a contributor to hypoxia in the Gulf of Mexico. In Iowa’s till-dominated watersheds, previous studies on nitrate transport in groundwater have relied on black box or unfractured porous media models, despite studies showing fracture control of nitrate transport. To investigate the role of fracture flow on watershed-scale nitrate transport, I will utilize a 3-D, fully-coupled, distributed-parameter, fracture-flow hydrologic model with a sophisticated, equivalent porous media (EPM) approach. Fracture flow parameters will be derived from X-ray computed tomography (CT) and laboratory column experiments conducted on 6.4- to 15-cm-diameter till core sampled from both drill core and 6-m-deep trenches associated with the recent installation of the Dakota Access Pipeline in central Iowa. Industry-developed fracture analysis programs and discrete fracture network (DFN) models will be used to compute the properties of the EPM. Results will be compared to existing nitrate-transport models for a watershed in central Iowa.