Remote Sensing Protocols for Inventory of Nutrient Management Practices
Title: Development of remote sensing protocols for inventory of nutrient management practices: Permanent vegetative practices
Location: Statewide in 40 WQI HUC 12s
Time Period: 2014 -2016
Research Team: Robin McNeely, Jim Giglierano, Amy Logan, Sarah Porter, David James, Thomas Isenhart, and Calvin Wolter
Project Description: This grant funded the initial work for what evolved into the statewide conservation practices inventory mapping project that spanned four years and multiple funding sources. The proposal for this grant aimed to create a GIS dataset of permanent vegetative practices in three pilot HUC 12s using semi-automated software processes with existing landcover data and newly collected imagery. After testing the procedure, it was determined that the results were not satisfactory without human interpretation and editing. The project evolved to using ISU and DNR staff to manually find six vegetative and structural practices in 40 IWQI HUC 12s. Student interns visually identified and digitized conservation practices using aerial imagery and LiDAR-derived products such as hillshade and slope. Hillshade provides a three-dimensional view of the ground to supplement the natural color and infrared aerial photography. The conservation practices were collected as line and polygon features in a GIS dataset.
A second task of this grant was to define a mapping procedure to delineate permanent vegetation along streams that represents the riparian zone. Automated methods using imagery, NDVI and proximity to streams generated vegetation polygons far beyond the riparian zone especially in more forested areas of the state. Ancillary data such as alluvial soils and landscape position were tested to see if they improved the riparian designation. Alluvial soils were shown to be helpful but the process still required a staff person to review the preliminary results and make data modifications. This process proved faster than manual digitizing and provided more repeatable and consistent results however, it required good resolution spring CIR imagery.
About a year after this portion of the project was completed, QA/QC conservation practice data was made available for public download as it was reviewed and finalized at https://www.gis.iastate.edu/gisf/projects/conservation-practices. The entire statewide dataset was finally completed and online in May 2019.
Funders: This portion of the statewide project was funded by the INRC. The entire four year statewide project was additionally funded by the IDNR, IDALS, INREC, AmericaView and NLAE.
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