أثر العاصفة المتوسطية دانيال على البيئة الطبيعية والبنية التحتية بحوض وادي درنة

Abstract

This paper discusses the impact of the Mediterranean storm Daniel on the natural environment and infrastructure within the Wadi Derna basin. The study aimed to analyze the spatial patterns of flood damage within the city, examine the geomorphological and morphometric changes in the wadi channel resulting from the flood event, and analyze the temporal changes in natural vegetation cover within the basin.

The study relied on several research approaches. The historical method was used to trace the temporal changes that occurred in vegetation cover within the study area by analyzing and comparing satellite images. The comparative method was employed to compare the environmental conditions before and after the flood event. In addition, the descriptive–analytical approach was used to describe the natural characteristics of the study area and to analyze satellite imagery in order to detect environmental changes.

The remote sensing approach was also applied by analyzing satellite images for the period (2022–2024) to measure the changes in the wadi channel after the flood using the area change rate equation. Furthermore, the Normalized Difference Vegetation Index (NDVI) was used to determine changes in vegetation density and the spatial extent of vegetation cover.

Among the most important results of the study, the total volume of water that fell across the entire basin was estimated at 111,880,000,000 cubic meters within one hour, assuming an average rainfall rate of 200 mm. The width of the wadi channel at the first bridge increased from 76 meters before the flood to 240 meters after the flood, representing the largest degree of channel expansion. Dense vegetation occupied the largest area in 2022, covering 7,128.4 hectares, but its area decreased to 2,387.5 hectares in 2024, representing a change rate of –66.5%.

The study concluded with several recommendations that may contribute to reducing the escalation of environmental disasters in the future