Analysis of spatial and temporal drought variability in a tropical river basin using palmer drought severity index (PDSI)
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Date
2017-08-31Author
Wambua, Raphael M.
Mutua, Benedict M.
Raude, James M.
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Analysis of spatial and temporal drought variability in the upper Tana River basin using Palmer Drought
Severity Index (PDSI) was conducted. The drought is critical for formulation of mitigation measures in
the river basin. A monthly temporal and 90-m spatial resolution was applied. This was achieved within
ArcGIS environment. Climatic data for 1970 to 2010 was used for computation of the PDSI while the
missing data sets were filled using Artificial Neural Networks (ANNs). The results of PDSI for dry and
wet seasons at meteorological stations indicate that the time series plots for the PDSI values for dry
season are generally lower than those for the wet seasons. The PDSI values for meteorological stations
located at the lower elevation of the basin are lower than those located at higher elevation. On the other
hand, spatially distributed drought severity based on PDSI show that the ranges of maximum and
minimum drought severity values in 1970 are -0.868 to -0.804 and -0.675 to -0.610 respectively. These
values of drought severity occur respectively in the north-western and south-eastern areas of the basin.
PDSI values increased from the range -0.675 to -0.610 in 1970 and from -1.087 to 0.957 in 2010 for the
north-eastern areas of the upper basin. The south eastern areas of the basin are more prone to drought
risks than north-western parts. Use of the PDSI reflects the spatial heterogeneity and temporal
variability of drought across the basin. The drought assessment offer technical approach for
comprehensive understanding of drought for effective drought-induced disaster mitigation and its
management, with a view to reducing adverse effects on livelihoods.
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