Iowa BMP Mapping Project
The goal of the Iowa BMP (Best Management Practices) Mapping Project is to provide a complete baseline set of BMPs dating from the 2007-2010 timeframe for use in watershed modeling, historic occurrence, and future practice tracking. The BMPs being mapped are: Terraces, Water and Sediment Control Basins (WASCOB), Grassed Waterways, Pond Dams, Contour Strip Cropping and Contour Buffer Strips. We can't guarantee that mapped practices meet NRCS standards or that they are actually the indicated practice since no ground truthing is being performed. Data being utilized to digitize the BMPs include LiDAR derived products such as DEM, Hillshade and Slope grids; CIR aerial photography from the 2007-2010 timeframe, NAIP aerial photography and historic aerial photography. BMPs are being collected by 12-digit HUC and finished products can be downloaded from this site.
This project has been funded by the Iowa Department of Natural Resources, Iowa Department of Agriculture and Land Stewardship, Iowa Nutrient Research Center at ISU, National Laboratory for Agriculture and the Environment, the Iowa Nutrient Research and Education Council and AmericaView.
To supplement this project, the ISU GISF has created a tool to download the BMPs by watershed as a GIS dataset for the state of Iowa. Click here to use the tool. In order to download data, you will be asked for some identifying information. The majority of the HUC 12 datasets will have a column indicating presence in 2010, which is the named year of the inventory, even though data was collected from 2007-2010. For the 20% evaluated for historic and current practices, see project description below, those 325 HUC 12 datasets will have an additional two columns indicating presence in the 1980s and presence in 2016 as that was the first year of current imagery.
The GIS Facility is in the process of edgematching all HUC12 features to their neighboring HUC12s within their HUC8. The edgematching process entails clipping the features at the HUC12 boundary and then a staff person adjusts edge features so they line up with an adjacent watershed feature, if one exists. The map below shows the processing status of all Iowa watersheds. Upcoming watersheds have not been completed. Watersheds that are being reviewed have begun the edgematching process, but are not ready to download. Completed watersheds are ready to download and the data has been updated within the application; watersheds that have not been completed still have the original data to download. Edgematching between HUC8s is happening concurrently as enough become ready to make the process feasible. The goal is to have all HUC12s completed during fall 2020 and possibly all HUC8s also. The map below is updated as HUC status changes, along with the date of change.
A companion project to the 2010 baseline inventory data tracks whether or not a particular conservation practice was evident in the 1980s or in current 2016-2018 imagery. The goal of this project is to assess a representative sample of HUC12 watersheds across the state in order to determine the trends in overall changes in practice levels from the 1980s to 2010 and on to 2018. For the 1980s review, practices that are identified as partially existing are split at the relevant location and each piece is identified with the necessary status. No new practices are digitized from the 1980s imagery, only practices existing in the baseline inventory are evaluated. With the current imagery, practices existing in the inventory are evaluated like the 1980s; new practices are digitized and added to the dataset. The evaluation procedure is being done on 20% of the entire state’s HUC 12 collection; random sampling is done by HUC 8 to choose which HUCs are processed. After a HUC 12 has QA/QC performed it is then evaluated for 1980s and current imagery presence or absence and the Historic Occurrence map, shown below, is updated.