Using GIS, we mapped the average and total accumulations of drought over the region, and plotted 1254 dust source points (1005 in the Southern Great Plains, 249 in the Chihuahuan Desert). To obtain drought history for each of the dust source points, we identified the nearest drought data pixel to the dust point using the Euclidean distance method, and obtained drought intensity at the time of the dust event as well as averages for 1-, 2-, and 5- years prior at the dust points and in regions of 30, 60 and 100 km radius around the dust points. Using buffer zone analysis we investigated the temporal and spatial conditions of the drought intensity around the dust points. Scatter matrices, frequency distributions and statistical analyses were used to investigate the different effects drought may have on dust activity over time, geographic region and land type.
Results indicate that dust points in the Chihuahuan Desert are highly concentrated in areas of severe to extreme drought, while those in the Southern Great Plains span a wider range of drought conditions. There were an increased number of dust events in those areas which were experiencing or recovering from severe to exceptional drought conditions, especially in the southwestern Southern High Plains west and south of Lubbock, a region dominated by non-irrigated cropland. The effects of drought intensity on dust sources were seen more at longer time scales (2 – 5 years), especially in the Plains; at the shortest time scale (0 – 1 years), drought has a weaker association with the locations of dust storm initiation points. Increasing the spatial size of buffer distance around the dust points skews towards stronger drought conditions in the desert, but weaker drought conditions in the plains. Finally, at every temporal and spatial scale, the drought intensities associated with Southern Great Plains and Chihuahuan Desert dust storm initiation points are significantly different.
Our study highlighted that drought, especially when extending over multiple years, indeed appears to play some role in driving dust storms in the Southwest United States, though it appears to be more locally-focused and likely magnified by the more intensive land use in the Southern Great Plains region than in the Chihuahuan Desert.