Equipping conservation practitioners with quantitative estimations of sediment and P reduction from BMPs
Issue
Water bodies worldwide are facing increasing pollution from sediment and phosphorus (P), threatening aquatic ecosystems and water quality. This environmental issue poses significant challenges to sustainable water resource management and necessitates effective solutions to mitigate its impacts. Numerous water quality models, tools, and estimators are available for predicting P loss from agricultural fields and watersheds. Many of these approaches can be challenging and complex to use, requiring specialized knowledge and expertise for proper implementation. This can be a challenge for conservation planners, who could benefit from applying these approaches to prioritize best management practices to address sediment and P in agricultural landscapes.
The Daily Erosion Project (DEP) and the Agricultural Conservation Planning Framework (ACPF) are two tools that simplify the complexities of required inputs and outputs in soil erosion and conservation planning. Tailored for the Midwest region of the U.S. and harnessing the power of a process model, the DEP offers a user-friendly approach for daily soil erosion estimation. ACPF uses geographic information systems and geospatial data to identify critical sources areas to target conservation practices and locates opportunities for their placement.
Objective
To address the duality of these two approaches and to provide stakeholders with needed quantitative information and certainty, researchers plan to harness the quantitative and computational prowess of DEP and the accessibility and planning strength of ACPF into a singular, integrated tool for conservation practitioners. The primary goal of this research is to develop an easy-to-use tool that would utilize quantitative sediment and P loss outputs from DEP in ACPF to: (i) simulate, identify and prioritize areas of high erosion and P transport potential; (ii) characterize potential BMP placement; and (iii) quantify potential sediment and phosphorus reduction and costs at different scales, from field to the small catchment level.
Approach
The project will employ a multi-faceted approach to achieve its objectives:
- Assess the various approaches and tools that can be used in Watershed Erosion Prediction Project (WEPP) for simulating sediment and P transport for adaptation into the tool.
- Develop an independent, downscaled DEP model to simulate sediment and P loss potential of fields or small catchments using high-resolution field data.
- Incorporate the downscaled DEP sediment and P model into the ACPF Financial and Nutrient Reduction Tool (ACPF FiNRT) framework to produce sediment and P reductions and costs for BMP scenarios for fields and small catchments.
Project Updates
Note: Project reports published on the INRC website are often revised from researchers' original reports to increase consistency.
July 2025
Work continues on preparing a version of the ACPF OFETool that can be run anywhere in the DEP domain. A draft version of the OFETool for inclusion in the ACPF has been finalized that accesses DEP web services and requests DEP model runs to summarize. The draft tool runs a two-step approach of the tool. 1 - Obtain DEP info; 2 - Run a HUC12 OFE assessment. However, the draft OFETool does not yet access the DEP tillage rasters as those only became available as a web service in late June.
To evaluate the OFETool as a runoff and soil loss model, Dr. Luquin is running the OFE Tool on all the STRIPS1, STRIPS2 and Minnesota Discovery Farms control and treatment sites where monitoring data is available. These simulations are meant as a general troubleshooting guide, not a calibration/validation, as the OFETool is not designed to replace the WEPP simulation model -- as it models top of slope effects with aggregated results based on long time periods (currently 6 years) and omits small scale, soil, slope and land management variations. These aggregations are in the same spirit of a general indicator, similar to the existing FinRT nitrogen loss tools.
Remaining work during the extended timeframe includes adding web service queries to the tillage layer, estimating phosphorus loads from sediment loss and estimating the practice reduction fraction.
Related activities and accomplishments
2 presentations
Proposal submitted: Remote sensing of residue cover via commercial satellite assets – NASA CSDA ($99,000)
January 2025
Previous PI Luquin moved to a position with the University of Minnesota on September 15. He remains committed to completing the project and the remainder of the project period was mostly devoted to paperwork changing PI from Luquin to Brian Gelder at ISU. Minor amounts of additional project work consisted of building an Ag Conservation Planning Framework ArcGIS tool to enable sharing of the OFETool process with GIS professionals and watershed managers.
Related activities and accomplishments
Previous PI Luquin oversaw the submission of a manuscript on application of the OFEtool (Overland Flow Element; a model component of the Water Erosion Prediction Project model) to Earth Surface Processes and Landforms (ESPL) journal; it was published online August 27, 2024, and is available at https://doi.org/10.1002/esp.5978.
The OFEtool was presented during his attendance at the 2024 Iowa Water Conference, Sept. 10-11, 2024 in Coralville, Iowa. The presentation was attended by about 40 participants.
June 2024
Since the last report, significant advances have been made in advancing our project objectives. A pivotal achievement includes the development of a down scalable version of the DEP (named OFEtool), which now facilitates precise estimations of soil displacement and runoff within the subfield scale for every agricultural field in the DEP domain. Moreover, our development of the OFEtool has brought to light certain mistakes and inconsistencies in our previous DEP simulations. Recognizing these errors has prompted us to dedicate significant effort to improving DEP simulations, ensuring the reliability of our soil erosion data as they form the essential basis feeding into the OFEtool. In parallel, progress has been made on scholarly dissemination, with a journal article detailing the down scalable version of DEP prepared and submitted for peer-review in the Earth Surface and Landform Processes Journal. Currently, we are navigating the review process, anticipating its contribution to the broader scientific community upon publication. Building on the success of the initial version of the OFEtool, efforts have also been focused on integrating it into the ACPF toolbox framework. This integration involves harmonizing its structure and input naming conventions with existing ACPF tools to ensure seamless usability across diverse applications within the ACPF framework. Initially, the OFEtool will provide ACPF users and developers with essential runoff and sediment data. A key component of this integration is the ongoing development of an API designed to interface with the DEP server, enabling streamlined access to simulation data for any HUC12 watershed within the DEP domain. Subsequent iterations will expand its capabilities to include phosphorus load calculations, enhancing its utility in comprehensive watershed management strategies. In addition to our efforts in obtaining sediment loads, progress has also been made in simulating phosphorus loads. To achieve this, we will implement the Annual Phosphorus Estimator Tool (APLE), chosen for its efficiency, robustness, and calibration-free operation. Furthermore, substantial progress has been achieved in gathering essential inputs—such as soil properties (clay content, organic matter, soil P, etc), field-specific land use data, and management details like manure and fertilizer application rates—necessary to run APLE effectively. These efforts are currently focused on test HUC12s within the Iowa SouthFork region. All these inputs are either obtained directly or derived from ACPF and the OFEtool. This ongoing work will ensure comprehensive data readiness for running APLE across any field within the DEP domain. Initial simulations have yielded promising results, laying the groundwork for future validations. In the upcoming semester, the team plans to validate this simulation approach using selected experimental fields.
Related activities and accomplishments
3 presentations and others planned.
A journal article was submitted to Earth Surface Processes and Landforms: Luquin, E. , Ferrie, C., Gelder, B., Herzmann, D., Zimmerman, E., James, D., Cruse, R., Isenhart, T. (2024). Estimating erosion vulnerability for agricultural fields using the Daily Erosion Project: the OFEtool. Manuscript submitted and under review.
January 2024
Over the past six months, our team has been diligently working on the two primary objectives of our grant. Under Objective 1, we analyzed various WEPP tools and spreadsheet load estimators for estimating sediment and phosphorus transport. This phase also included selecting experimental fields and small watersheds with existing nutrient data, vital for testing our modeling approaches. In achieving Objective 2, we developed the first version of the "OFEtool", a GIS tool that downscales Daily Erosion Project (DEP) hillslope soil loss estimations from the HUC12 watershed level to a detailed field and pixel level (3x3 m). This tool is key in estimating sediment with greater resolution for our project's next stages. We've tested OFEtool in multiple HUC12 watersheds in Iowa and randomly chosen one for publication. Currently, we're also working on drafting a manuscript about OFEtool for the 'Earth Surface Processes and Landforms' journal, focusing on the special issue “Advances in Soil Erosion and Soil Conservation”.
Other Activities
2 Presentations
Presentation to the Iowa Nutrient Reduction Science Team (08/02/2023) titled "A GIS-based WEPP modeling approach to locate and quantify vulnerable fields prone to hillslope soil loss" Presentation at the ISU GIS day (11/15/2023) titled "Integrating Daily Erosion Project outputs into the ACPF Toolbox: A strategy to locate vulnerable fields and prioritize BMPs in agricultural landscapes"