TITLE:
The Influence of Tropical Cyclones to the Plant Productivity Indices along the Coast of Tanzania
AUTHORS:
Kombo Hamad Kai, Yohanna Wilson Shaghude, Agnes Lawrence Kijazi, Christian B. Uiso
KEYWORDS:
Tropical Cyclones (TCs) Impacts, Normalized Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Rainfall, MODIS), Tanzania
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.11 No.3,
July
15,
2021
ABSTRACT: The study investigated the influence of Tropical
cyclone (TCs) to the plant productivity indices along the coast of Tanzania
using both field observations and change detection methods. These indices are
normally designed to maximize the sensitivity of the vegetation characteristics
and are very crucial in monitoring droughts intensity, yield and biomass
amongst others. The study used three types of satellite imageries including the
16 days Moderate Resolution Imaging Spectroradiometer (MODIS) of 250 × 250 m resolution; 8 days Landsat 7 enhanced
thematic mapper (ETM) with resolution of 30 × 30 m composites, and 5 Landsat 8 (LC8) images, to determine the patterns
and the variability of the Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) and TCs impacts on
vegetation. Moreover, we used Tropical
Rainfall Measuring Mission (TRMM) data and the daily to monthly rainfall
data from Tanzanian Meteorological Authority (TMA). The change detection
between the pre and post storm (TCs) conditions was used to analyse inter
annual variability of EVI over Chwaka, Rufiji and Pugu— Kazimzumbwi. The
changes in NDVI and EVI and monthly rainfall at the coastal stations were
calculated, plotted and analyzed. The results revealed that, highest EVI values
over coastal Tanzania were observed during March and April, and minimum (low) values in November. The results for EVI
changes based on pre and post storm conditions revealed that most observed
stations and most TCs led to significant EVI changes which ranged from -0.05 to 0.19, and -0.3 to 0.22, for MODIS and L7 ETM data,
respectively. As for the spatial changes in NDVI results revealed that, TCs
(Besija and Fobane) were associated with positive NDVI changes i.e. (enhancement) of >0.51 and >0.31, and NDVI reduction (i.e. negative changes) of -0.19 for Chwaka and Rufiji, respectively. Besides the
results revealed that, TCs episodes have induced a land cover changes from i.e. water covered areas changed
to be vegetation covered especially over the shorelines and inter tidal areas.
Indeed, these results were consistent with the analysis of rainfall patterns
which indicated that low rainfall occurred in low NDVI areas and vice versa.