Publicação
Multidecadal water quality trends across 15 European river basins along a Mediterranean climate gradient
| Resumo: | Water quality degradation is a major issue in Mediterranean regions, but identifying the key natural and human drivers remains challenging, requiring large–scale studies for meaningful synthesis and comparison. This study analyzed a vast Mediterranean dataset spanning 89,015 km 2 across 15 Iberian river basins along a climate gradient (cooler-wetter north to warmer-drier south), 3 decades, 3441 stations, 19 parameters, and ∼15 million observations. It is the first study of this scale in the region, utilizing custom scripts for automated data compilation and processing. The study revealed an evident north–to–south water quality decline, with rising electric conductivity, pH, total suspended solids, nitrogen, phosphorus, organic carbon, and sulphate, alongside reduced dissolved oxygen and transparency. This pattern correlated with the latitudinal climate gradient and intensified agriculture in the south (Pearson correlation coefficient: 0.1 to 0.53; Spearman's rank correlation coefficient: 0.17 to 0.56), while increased forest cover had a mitigating effect (Pearson: 0.50 to 0.07; Spearman: 0.51 to 0.10). Multidecadal trend analysis revealed a shift around 2005 with most parameters decreasing, except for nitrate and phosphate, which rose likely due to the 2004/05 drought reducing river dilution and expanded irrigated agriculture, especially in Alentejo with the Alqueva reservoir. |
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| Autores principais: | Costa, Diogo |
| Outros Autores: | Liu, Jian; Palma, Patrícia |
| Assunto: | Historical monitoring Mediterranean regions Water quality Watersheds |
| Ano: | 2025 |
| País: | Portugal |
| Tipo de documento: | artigo |
| Tipo de acesso: | acesso embargado |
| Instituição associada: | Instituto Politécnico de Beja |
| Idioma: | inglês |
| Origem: | Repositório Institucional do IPBeja |
| Resumo: | Water quality degradation is a major issue in Mediterranean regions, but identifying the key natural and human drivers remains challenging, requiring large–scale studies for meaningful synthesis and comparison. This study analyzed a vast Mediterranean dataset spanning 89,015 km 2 across 15 Iberian river basins along a climate gradient (cooler-wetter north to warmer-drier south), 3 decades, 3441 stations, 19 parameters, and ∼15 million observations. It is the first study of this scale in the region, utilizing custom scripts for automated data compilation and processing. The study revealed an evident north–to–south water quality decline, with rising electric conductivity, pH, total suspended solids, nitrogen, phosphorus, organic carbon, and sulphate, alongside reduced dissolved oxygen and transparency. This pattern correlated with the latitudinal climate gradient and intensified agriculture in the south (Pearson correlation coefficient: 0.1 to 0.53; Spearman's rank correlation coefficient: 0.17 to 0.56), while increased forest cover had a mitigating effect (Pearson: 0.50 to 0.07; Spearman: 0.51 to 0.10). Multidecadal trend analysis revealed a shift around 2005 with most parameters decreasing, except for nitrate and phosphate, which rose likely due to the 2004/05 drought reducing river dilution and expanded irrigated agriculture, especially in Alentejo with the Alqueva reservoir. |
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