Análise da dinâmica de campo de dunas eólicas costeiras na Praia de Chongoene – Província de Gaza

Abstract

The present study aims to analyze the dynamics of coastal aeolian dune fields at Chongoene Beach, located in Gaza Province, Mozambique, between 1996 and 2023. To achieve this objective, satellite imagery (LANDSAT) was used to classify beach land use and cover. The Snowfall Index (NDSI) was calculated to map and quantify dune field areas. Atmospheric data (precipitation and winds) obtained from the ERA5 sensor were used to assess the influence of atmospheric variables on dune field dynamics. The mobility index, according to Lancaster (1988), was calculated to quantify the mobility of the dune field areas of Chongoene Beach. The results indicate a significant reduction in the total dune area, from approximately 1,000 hectares in 1996 to approximately 580 hectares in 2023, representing a loss of 42%. The greatest reductions occurred in the northwestern portion of the dune field, directly influenced by the predominance of northwesterly winds, with average intensities of up to 7 m/s. Analysis of land cover also reveals a sharp decline in vegetation, which fell from 36.8% in 1996 to less than 10% in 2023, intensifying the system's vulnerability. There was also an inverse relationship between precipitation and dune mobility: during the rainy season, high soil moisture reduced wind mobility (a minimum of 20 in January), while in the dry season, marked by low precipitation and strong winds, mobility reached its maximum (380 in September). Finally, it was highlighted that the evolution of sediment dynamics in Chongoene highlights an accelerated process of dune retreat, compromising the natural protection of the coastline and local biodiversity.