The variables used in the analysis encompass vegetation, climate, and environmental conditions in the Godoria region. The Normalized Difference Vegetation Index (NDVI) reflects vegetation status derived from satellite data, while soil moisture and land surface temperature (LST) provide information on water availability and surface heat. Climatic factors include rainfall, the Standardized Precipitation Index (SPI) as a measure of drought conditions, and both minimum and maximum temperatures (Temp Min and Temp Max), which influence plant physiology and evapotranspiration. Potential evapotranspiration (PET) indicates the potential water deficit driven by climatic conditions. Finally, sea level serves as a relevant oceanographic indicator in the arid coastal context of Djibouti, with potential indirect impacts on local climate dynamics and water availability.
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Fig. 1. (a)Estimation of relative importance of climate variables as predictors of
NDVI. (b) Pearson correlation coefficient between NDVI and climate variables. |
Table 1. Mann Kendall Trend and
Theil-sen slope statistics of NDVI and climate variables from 1987 to 2022.
|
|
Theil-sen
slope |
p.value |
p.value |
|
|
NDVI |
0.858 |
0.859 |
||
|
Sea level |
0.646 |
0.646 |
||
|
0.000 |
NA |
0.000 |
NA |
|
|
SPI |
0.000 |
0.917 |
0.000 |
0.917 |
|
Temp
Min |
0.057 |
0.109 |
0.194 |
0.109 |
|
Temp
Max |
0.072 |
0.173 |
0.166 |
0.172 |
|
0.739 |
0.739 |
|||
|
0.046 |
0.649 |
0.085 |
0.649 |
|
|
LST |
0.720 |
0.720 |
