Scientific and Technological Tools to Implement Iowa Nutrient Reduction Strategy
New scientific tools and techniques and an improved understanding of the physical, chemical and biological processes are needed to predict nutrient mobilization, fate and transport in Iowa. It also is important to improve scientific understanding of the benefits derived from best management practices (BMP), from individual practices through watershed-integrated approaches.
Four research projects focus on developing scientific and technological tools to aid in the implementation of the Iowa Nutrient Reduction Strategy. A science and process-based framework using an integrated watershed approach will improve understanding of the complex nutrient management issues in Iowa, and the basis for possible solutions.
The first project will quantify the benefits of BMPs and land management practices, and associated hydrology on nutrient loading to water resources using hydrodynamic modeling tools. Three new models will be implemented to quantify nitrogen removal benefits over a range of precipitation and stream flow. The second project will quantify the benefits of BMPs and land management practices, and associated hydrology on sediment and phosphorus loading based on field observations. The third project will develop a functional, web-based database of available nutrient data sets in Iowa to be used by the Iowa Nutrient Reduction Center. The fourth project involves measurement of field data parameters to support modeling, including field monitoring of nitrogen, sediment and phosphorus inputs and outputs for select BMPs installed in priority watersheds.
Work continues to monitor the Slough Creek CREP wetland for nitrate, dissolved oxygen, temperature and conductivity. The two water quality sensors deployed upstream and downstream of the wetland have provided continuous measurements since 2014 of incoming and outgoing NOx (nitrite + nitrate) concentrations, along with other water quality variables. A coupled hydrologic and water quality model that was built to simulate and evaluate the nutrient removal dynamics of an Iowa wetland under variable hydrologic conditions shows nitrogen load reductions of 57 percent (2014), 59 percent (2015) and 21 percent (2016), for a three-year average of 46 percent. In another project, recent work derived a new way to estimate phosphorus concentrations without expensive lab testing for total phosphorus. By using turbidity, o-phosphorus and stream discharge, total phosphorus loads are accurately estimated. These three parameters can be remotely and continuously monitored using sensor technology. To this end, two real-time ortho-phosphorus measurement devices were deployed on the Iowa River near New Providence, and the English River at Kalona. In addition, one unit is deployed at the Cedar Rapids Wastewater Treatment Plant and one will be deployed at the groundwater spring at the DNR Fish Hatchery near Manchester. These new deployments of continuous sensors will add to existing information about phosphorus loss in Iowa.
One project under this umbrella title is complete. The project studied floodplain phosphorus distribution in an agricultural watershed, and its role in contributing to in-stream phosphorus load. Over three years, researchers collected and analyzed soil samples from the floodplains, streambed and banks of the Turkey River to estimate the total phosphorus concentration in soils at each location. Key findings: Phosphorus concentration in floodplain soils is closely related to soil fine particle content; topography and flood characteristics control distribution of soil fine particle content and phosphorus concentration; lower floodplain terraces are short-term phosphorus storage locations, while upper floodplain terraces provide long-term phosphorus storage; dense root systems on floodplain sediments reduce erosion and total-phosphorus loss.
Four projects are underway. Modeling tools are being used in the Upper Roberts Creek watershed to study the potential impacts on watershed nitrogen loads if there was widespread use of cover crops, and nitrate removal wetlands were constructed. In another project, researchers are analyzing soil samples to estimate the total phosphorus concentration in soils at the floodplains, streambed and banks of the Turkey River. This is helping to identify where the greatest amount of erosion is occurring. In the third project, the Iowa Water Quality Information System online tool is available at http://iwqis.iowawis.org. It offers access to real time nutrient data with a range of water-related information such as precipitation, stream flow and soil moisture. Improvements to the system are ongoing. The Iowa Institute of Hydraulic Research network of 26 water quality stations was fully deployed for the 2015 water season. Planning has begun to site an additional 15 water quality monitoring stations for the 2016 water season. Coverage will include all of Iowa’s major rivers.
Several projects are underway. One is using modeling tools to determine the impact on the Upper Roberts Creek watershed if there was widespread use of cover crops and other stacked nutrient management practices. In another project, researchers are analyzing soil samples to estimate the total phosphorus concentration in soils at the floodplains, streambed and banks of the Turkey River. Development continues on a web-based interactive database for the Iowa Nutrient Research Center. The online tool is running and improvements are being made. The IIHR network of 26 water quality stations was fully deployed for the 2015 water season. Of these, 21 were in the same locations as the 2014 sampling season, with five in new locations. Additional sensors that target Water Quality Initiatives have been proposed.
The HydroGeoSphere model generation for the Upper Roberts Creek watershed is nearing completion and the calibration process is beginning. Over the past quarter, a new grid was developed in an effort to increase the simulation speed and decrease errors. Another project focuses on the estimation of the total phosphorus concentration in soils at the floodplains, streambed and banks of the Turkey River. So far, 165 soil samples from five field sites have been analyzed, which is about one-third of the total samples taken. Development has begun on a web-based interactive database for the Iowa Nutrient Research Center. The online tool is running and on the web, but not yet available to the public. Improvements are in progress. In the project that is collecting field data to support modeling, there are 26 water-quality stations in place in four watersheds for the 2015 sampling season. Five are new since the 2014 sampling season.
Four connected research projects focus on developing scientific and technological tools to aid in the implementation of the Iowa Nutrient Reduction Strategy. The HydroGeoSphere model generation for the Upper Roberts Creek watershed is nearing completion and the calibration process is beginning, using crop and weather data from 2013. The calibrated model will be validated using 2014 data. Another project focuses on the estimation of the total phosphorus concentration in soils at the floodplains, streambed and banks of the Turkey River. Five field sites have been surveyed and soil samples are being analyzed. Development has begun on a web-based interactive database for the Iowa Nutrient Research Center. Content includes nutrient data that have been collected from various sources. The final project involves the collection of field data to support modeling. A total of 21 water-quality stations were deployed in four watersheds during the 2014 sampling season, and data are being analyzed. The sensors were removed in November to protect from winter weather and will be redeployed this spring.
A suite of research projects focus on developing scientific and technological tools to aid in the implementation of the Iowa Nutrient Reduction Strategy. Model development is underway in both Beaver Creek (Cedar River) and Roberts Creek (Turkey River). Current research in Beaver Creek seeks to understand the impact of tile drainage on stream flow and the incorporation of field terraces on the land surface. A model in Roberts Creek has been established, and simulations are being run, to validate the model for various historical rainfall events. In a phosphorus project, cross sectional hydraulics and geomorphic analysis is underway at study sites in the Turkey River. A program for soil sampling has been developed and samples are being extracted for processing over the winter.