EVALUATION OF DROUGHT LEVEL AND ANTHROPOGENIC LAND USE IMPACT ON DUST
EMISSION IN SOUTHWESTERN UNITED STATES: QUANTITATIVE AND SPATIO-TEMPORAL
ANALYSIS OF DUST POINT SOURCES
Abstract
Quantifying the effect of anthropogenic land use change on dust emission
is a contentious issue. In this research, 1508 dust point sources were
detected in the Southern High Plains and Chihuahuan Desert regions of
the United States for 2001-2016, encompassing a period of extreme
drought. These points were subjected to quantitative and spatio-temporal
analysis. Point pattern analysis showed a significant cluster of these
points in West Texas (Nearest Neighbor Ratio = 0.33, р <
0.001) where cultivated lands and grasslands are dominant land cover.
Spatial observation suggests that the geographic center of dust points
in these regions shifts away from bare soil and shrublands toward
grasslands and cultivated lands as drought level increases, while it
shifts away from grasslands and cultivated lands towards bare soil and
shrublands in cases of no drought. Chi-square test captured a
significant association between land use type and drought level on dust
emission (χ2 (6) = 47.33, р < 0.001). However, Cramer’s V
value (0.13, р < 0.001) indicates that the association
captured by the chi-square is weak, suggesting that other factors,
perhaps meteorological variables, are at play in the spatial
distribution of dust sources in this region. The proportion of dust
points differs significantly during severe/exceptional droughts versus
no drought or abnormally dry/moderate drought in both cultivated lands
and grasslands. The proportion of dust points in bare lands and
shrublands, however, did not significantly change between no drought and
severe-exceptional drought. These results suggest anthropogenic land use
in southwestern U.S. is significantly associated with drought in terms
of dust emission. Human activity amplifies of the effects of drought by
increasing soil erodibility; thus, adopting land management practices to
resist wind erosion is crucial. Further investigations on a global scale
should provide more information on this association.