TITLE:
Meteorological Drought Detection and Forecast Using Standardized Precipitation Index and Univariate Distribution Models: Case Study of Bamako, Mali
AUTHORS:
Alikalifa Sanogo, Prince Appiah Owusu, Roland Songotu Kabange, Bakary Issa Djire, Racheal Fosu Donkoh, Nasser Dia
KEYWORDS:
Standardized Precipitation Index (SPI), Rainfall Variability, Univariate Proba-bility Distribution, Drought, Bamako
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.11 No.7,
July
12,
2023
ABSTRACT: As an extended period of unusually dry weather conditions without
sufficient rain, drought poses enormous risk on societies. Characterized by the
absence of precipitation for long periods of
time, often resulting in water scarcity, droughts are increasingly posing significant environmental challenges. Drought is therefore considered an important element in the management of water resources, especially groundwater resources
during drought. This study therefore sought to investigate the rainfall
variability and the frequency of drought for the period 1991 to 2020 in Bamako
based on monthly rainfall data from Bamako-Senou gauge station. The
standardized precipitation index (SPI) for 12-month, 6-month and 3-month
timescales and the SPI for annual totals were used to characterized drought in
the study area (Bamako). Univariate parametric
probability distributions such as Normal, Log-normal, Gumbel type I and
Pearson type III (P3) distributions were fitted with drought variables (severity and duration) for future planning
and management. Non-parametric test such as Mann-Kendall trend test was
also used to detect trend in annual rainfall data. The results showed that
based on 12-month SPI, Bamako experienced
two (02) extreme droughts one in July 2002 (SPI = -2.2165) and another
in June 2015 (SPI = -2.0598 QUOTE SPI=-2.0598 ). Drought
years represented 46.67% for the overall periods according to the SPI for
annual totals. The result further indicated
that based on the goodness of fit test, the P3 distribution represents
the best fitted distribution to both drought severity and duration over Bamako.
Bamako is expected to experience several severe severities with higher and shorter duration in the future.
Severities with 1, 2, 6, and 10-month duration had return periods ranged
from 2.4 to 3.8 years, while 5, 10, 20, 25, 50,
and 100-year return periods had 18.51, 26.08, 33.25, 35.50, 42.38, and 49.14 severities, respectively, and durations associated to these severities
were 19.8, 26.9, 33.5, 35.6, 42, and 48.2 months, respectively.