TITLE:
Assessment of the Impacts of Tropical Cyclones Idai to the Western Coastal Area and Hinterlands of the South Western Indian Ocean
AUTHORS:
Kombo Hamad Kai, Sarah E. Osima, Mtongori Habiba Ismail, Pacal Waniha, Hamad Asya Omar
KEYWORDS:
Tropical Cyclones, Zonal and Meridional Winds, Precipitable Water, Vertical Wind Shear, Low-Level Vorticity, Water-Borne Diseases, Deaths and Injuries
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.11 No.4,
October
29,
2021
ABSTRACT: Tropical Cyclones (TCs) are among the atmospheric
events which may trigger/enhance the occurrence of disasters to the society in
most world basins including the Southwestern Indian Ocean (SWIO). This study analyzed the dynamics and
the impacts of the Tropical Cyclone (TC) Idai (4th-21st March, 2019) which devastated most of the SWIO countries. The study used the
Reanalysis 1 products of daily zonal (u) and meridional (v) winds, Sea Surface
Temperatures (SSTs), amount of Precipitable Water (PRW), and relative humidity (Rh). The dynamics and movements of Idai were analyzed using the wind circulation at 850, 700, 500 and 200 mb, where
the TC dynamic variables like vertical wind shear, vorticity, and the mean
zonal wind were calculated using u and v components. Using the open Grid
Analysis and Display System (GrADS) software the data was processed into three-time
epochs of pre, during and post; and then analyzed to feature the state of the
atmosphere before (pre), during and post TC Idai using all datasets. The amount of precipitable water was used to map the rainfall on pre, during,
and post Idai as well as during its landfall. The results revealed that
dynamics of TC Idai was intensifying the weather (over Mozambique) and clearing
the weather equatorward or southward of 12°S, with low vertical wind shear over
the landfall areas (-3 to 3 m/s) and higher shear values (10 - 40 m/s)
northward and southward of the Mozambican channel. Higher moisture content (80
- 90%) and higher PRW (40 - 60 mm/day) mapped during Idai over the lowland
areas of Mozambique propagating westward. Higher low-level
vorticity values were also mapped over the landfall areas. More results revealed
that countries laying equatorward of 12°S, e.g., the
northern coastal areas of Kenya (Turkana and Baringo) and Tanzania, Idai disrupted
the 2019 March to May (MAM) seasonal rainfall by inducing long dry spell which
accelerated the famine over the northeastern Kenya (Turkana). Moreover, results
revealed that the land falling of Idai triggered intensive flooding which
affected a wide spectrum of socio-economic
livelihoods including significant loss of lives, injuries, loss of material
wealth, infrastructure; indeed, people were forced to leave their houses for quite a longtime;
water-borne diseases like malaria, cholera among others were experienced.
Furthermore, results and reports revealed that a large
amount of funds were raised to combat the impacts of Idai. For instance,
USAID/OFDA used about $14,146,651 for human aid and treatment of flood-prone
diseases like Cholera in Mozambique ($13,296,651), Zimbabwe ($100,000), and
Malawi ($280,000), respectively. Also a death toll of about 602 in Mozambique
and 344 in Zimbabwe, and more than 2500 cases of injured people were reported. Conclusively the study has shown that TCs including Idai and other are among
the deadliest natural phenomenon which great affects the human and his
environments, thus extensive studies on TCs frequency, strength, tracks as well as their coast benefit analysis should be conducted to reduce the societal
impacts of these TCs.