Torrential rainfall regimes, among others, are the origin of accelerated soil erosion. The Spanish southeastern Mediterranean region is characterised by an arid climate regime affected by extreme erosion episodes with an important loss of sediments. Soil erosion effects are even more noticeable in areas where soil has been anthropically degraded, as in the mining district of Sierra Minera de Cartagena. The present research focuses on monitoring and mapping the changes in the sediment distribution of iron oxides and hydroxyl (OH⁻) bearing minerals caused by a cold drop known in Spanish as 'DANA' in September 2019 on the Rambla del Beal. This short rambla is fed by sediments from its drainage basin and by mining residues, irrigating a wide agricultural area. When discharges overflow the rambla channel, residues spread over its floodplain and reach the ecological protected coastal lagoon Mar Menor. The objective of the study was mapping the mineral distribution of the mining materials eroded from the source areas and sedimented in Rambla del Beal during a DANA. The study was carried out using a pre- and a post-DANA image from the Sentinel-2 satellite. After masking vegetation, urban areas and water bodies, different band ratios (B4/B3, B11/B12, B8A/B6) and a Spectral Angle Mapper (SAM) classification were applied. Sediment deposits were identified in wider areas after the DANA. Iron oxides increased their extension by 11.08% in the central area (B3/B4 with R² of 0.84) and hydroxyl-bearing minerals increased by 8.95% in the Rambla del Beal's headwaters (B11/B12 with R² of 0.71). The SAM classification (with a 0.1 rad threshold and an overall accuracy of 87.33%) allowed the differentiation and classification of two ferric iron oxides (haematite and goethite) and one iron hydrous sulphate mineral (jarosite). Additionally, band ratio images were spatially overlaid with the soil land uses map layer of the cadastre in order to plot the land uses most affected by the transported sediments during the DANA. These results highlighted agricultural land as the areas (land uses) most affected by iron oxides deposition, as oxidation processes occur more rapidly in these areas. However, grassland and scrubland were the areas with the highest content of hydroxyl-bearing minerals, as water is accumulated in these places, which favours hydrolysis reactions.

中文翻译：

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使用 Sentinel-2 卫星图像监测矿山废弃物的沉积区域：西班牙东南部的案例研究

除其他外，暴雨状况是加速土壤侵蚀的根源。西班牙东南地中海地区的特点是干旱气候状况，受极端侵蚀事件的影响，沉积物大量流失。在土壤被人为退化的地区，如卡塔赫纳山脉的矿区，土壤侵蚀的影响更为明显。目前的研究重点是监测和绘制由 2019 年 9 月在Rambla del Beal上的一次冷降（西班牙语称为“DANA”）引起的氧化铁和含羟基 (OH ^- ) 矿物沉积物分布的变化。这条短短的兰布拉大道由其流域的沉积物和采矿残渣供给，灌溉了广阔的农业区。当排放物溢出兰布拉河道时，残留物会扩散到其漫滩并到达受生态保护的沿海泻湖Mar Menor。该研究的目的是绘制从源区侵蚀并沉积在Rambla del Beal的采矿材料的矿物分布图在 DANA 期间。该研究是使用来自 Sentinel-2 卫星的 DANA 前后图像进行的。在掩盖植被、城市地区和水体后，应用不同的波段比（B4/B3、B11/B12、B8A/B6）和光谱角映射器 (SAM) 分类。在 DANA 之后，在更广泛的区域发现了沉积物沉积物。氧化铁在中部区域（B3/B4，R ^{2为 0.84）增加了 11.08% 的延伸，} Rambla del Beal源头的含羟基矿物增加了 8.95% （B11/B12，R ²0.71）。SAM 分类（具有 0.1 拉德阈值和 87.33% 的总体准确度）允许区分和分类两种三价铁氧化物（赤铁矿和针铁矿）和一种含水硫酸铁矿物（黄钾铁矾）。此外，带比图像在空间上与地籍的土壤土地利用地图层重叠，以便绘制 DANA 期间受输送沉积物影响最大的土地利用。这些结果强调农业用地是受氧化铁沉积影响最大的区域（土地利用），因为这些区域的氧化过程发生得更快。然而，草地和灌木丛是含羟基矿物质含量最高的地区，因为这些地方积水，有利于水解反应。