• Introduction

The goal of the Arkansas SRA was to combine the best available statewide datasets with input from NRCS resource managers and their conservation partners to first model and then quantify the extent and distribution of potentially 31 NRCS targeted natural resource concerns. Of the total 31 NRCS identified natural resource concerns, it was agreed upon during the first Phase of the SRA  that only 29 of those actually apply within Arkansas; therefore only 29 were modeled and mapped during the initial Phase I inventory. This development of “weighted sum” raster GIS models during phase I of the Arkansas SRA helped identify the distribution and areal extent of these twenty-nine natural resource concerns within the NRCS service areas. The resulting models (raster GIS layers) depicted the extent of each of the 29 resource concerns modeled (one raster output per model) and these products were summarized to determine how many acres of Arkansas had been potentially impacted. The at-risk acres were computed by summarizing the area (acres) of each resulting model output where the resulting raster pixel values were greater than or equal to one. So during Phase I, essentially, the relative risk estimated from the ‘weighted sum models’ was not as important as the inventory of the total acres of “at risk” areas within Arkansas. Additionally, the assessment was to determine how many at-risk acres fall within the priority area delineations.

This statewide inventory of information will help guide and prioritize the Arkansas NRCS office efforts over the next five years.  The Phase I deliverables also included the completion of a summary worksheet for Arkansas’ resource concerns provided a summary of the extent (acres) of the at-risk areas for each of these twenty-nine natural resource concerns and a summary of the total acres that have already received treatment through NRCS programs.

During Phase II of this project we have worked closely with the NRCS Little Rock office to further refine our input datasets used for each of our 29 natural resource concern models while also refining the various model parameters to better reflect the ‘relative’ at-risk areas based upon the expert opinions and experience of Arkansas’ natural resource professionals.  The results of this model refinement are discussed within the “Results and Model Descriptions” section of this report.  After these models were modified during Phase II, the resulting modeled ‘relative risk’ raster datasets from each Natural Resource concern were summarized to the 12-digit Hydrologic Unit Code (HUC) watersheds within Arkansas.  This summary reporting step of this phase will be very helpful to NRCS leadership and staff when making decisions regarding the allocation of their resources to mitigate the relative risks associated with each of these natural resource concerns within Arkansas.  The aggregation and prioritization of these model outputs to the watershed boundaries will simplify management decisions as the NRCS district boundaries are aligned with these natural boundaries too.