Climatic and Environmental Drivers of NDVI Dynamics in an Arid Region: Predictor Importance, Correlation, and Trend Analysis (1987–2022)

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.

(a)   (b)

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	Mann kendall tau (τ)	p.value
NDVI	-0.001	0.858	-0.023	0.859
Sea level	0.001	0.646	0.057	0.646
Rainfall	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
Soil Moisture	-0.030	0.739	-0.057	0.739
PET	0.046	0.649	0.085	0.649
LST	-0.222	0.720	-0.111	0.720

 

Abdi-Basid ADAN, 2024