DOI: 10.5061/dryad.44j0zpc9x
title: Assessment of acetochlor use areas in the Sahel region of Western Africa using geospatial methods

description: The goal of this study was to determine the co-occurrence between
 acetochlor use on crops and potentially vulnerable soils in the Permanent
 Interstate Committee for Drought Control in the Sahel region of Western
 Africa. Acetochlor, a pre-emergence herbicide, is used primarily on row
 crops and has the potential to reach groundwater or surface water
 following a rain event shortly after application. Off-field transport is
 often determined by soil properties; therefore, soils within potential use
 areas were assessed and mapped to establish areas with soils vulnerable to
 leaching and/or runoff. Corn and cotton production areas were used as
 surrogate crops for high potential use areas of acetochlor within areas
 identified using GlobCover land use data and the Spatial Production
 Allocation Model agricultural statistics data. The geospatial analysis
 identified approximately 462 million ha of potentially vulnerable soils in
 the Sahel region of which 65.7 million ha are within agricultural areas.
 An adjustment for corn and cotton production areas showed that 2.2 million
 ha or 3.3 % of agricultural fields could have potential restrictions for
 acetochlor use. Approximately 0.159 million ha of soils or 0.24% of
 agricultural fields are in the presence of shallow groundwater, defined by
 depth &lt; 9 m.  In addition, 0.0128 million ha or 0.02 %
 were determined to be adjacent to surface water bodies. To understand the
 uncertainty associated with the use of specific land cover datasets, an
 overlay assessment was conducted using alternative data sources. Overlap
 between selected land cover datasets in the Sahel region varies and ranges
 from 24.7% to 75.5% based on a merged 2009 GlobCover and CCI LC datasets.
 In comparison with the merged 2005 and 2009 GlobCover dataset, the
 cropland overlaps range from 38.9% to 85.0%. This demonstrates that the
 choice of land cover dataset can have a significant impact on a spatial
 assessment. Results from this assessment demonstrate that only a small
 fraction of vulnerable agricultural soils across the region may be a risk
 for contamination by acetochlor of groundwater or surface resources, based
 on product label recommendations. Given the availability of spatial data
 in a region, the methods contained herein may additionally be used in
 other localities to provide similar information that can be helpful for
 water quality management.
description: See journal article Figure 8 for the detailed processing
 steps
description: Included in this database are the following layers:
 CILSS_BND - Vector based dataset representing the countries in
 the CILSS considered in this assessment LU_PUA - Raster
 layer represeinting the Potential Use Area (PUA) of acetochlor in the
 CILSS PUA_ARP - Raster layer representing soils
 adhering to the ARP (www.arpinfo) 3-2-1 soil criteria
 PUA_ARP_SGW - Vector layer representing the ARP 3-2-1 soils
 within the potential use areas overlapping shallow (&lt;9.0m)
 groundwater PUA_ARP_SW - Vector layer representing the
 ARP 3-2-1 soils that are adjacent to surface waterbodies such as rivers in
 the CILSS Attribute filed for the data set are not
 provided. Just the outlines of the areas resulting from GIS
 assessments