Research Institute for Integrated Management of Coastal Areas, Universitat Politècnica de València, C/Paraninfo, 1, 46730 Grau de Gandia, Spain.
Geo-Environmental Cartography and Remote Sensing Group, Universitat Politècnica de València, Camí de Vera s/n, 46022 Valencia, Spain.
Sensors (Basel). 2023 Apr 19;23(8):4096. doi: 10.3390/s23084096.
Tablas de Daimiel National Park (TDNP) is a unique inland wetland located in the Mancha plain (Spain). It is recognized at the international level, and it is protected by different figures, such as Biosphere Reserve. However, this ecosystem is endangered due to aquifer overexploitation, and it is at risk of losing its protection figures. The objective of our study is to analyze the evolution of the flooded area between the year 2000 and 2021 by Landsat (5, 7 and 8) and Sentinel-2 images, and to assess the TDNP state through an anomaly analysis of the total water body surface. Several water indices were tested, but the NDWI index for Sentinel-2 (threshold -0.20), the MNDWI for Landsat-5 (threshold -0.15), and the MNDWI for Landsat-8 (threshold -0.25) showed the highest accuracy to calculate the flooded surface inside the protected area's limits. During the period 2015-2021, we compared the performance of Landsat-8 and Sentinel-2 and an R value of 0.87 was obtained for this analysis, indicating a high correspondence between both sensors. Our results indicate a high variability of the flooded areas during the analyzed period with significant peaks, the most notorious in the second quarter of 2010. Minimum flooded areas were observed with negative precipitation index anomalies since fourth quarter of 2004 to fourth quarter of 2009. This period corresponds to a severe drought that affected this region and caused important deterioration. No significant correlation was observed between water surface anomalies and precipitation anomalies, and the significant correlation with flow and piezometric anomalies was moderate. This can be explained because of the complexity of water uses in this wetland, which includes illegal wells and the geological heterogeneity.
塔巴雷斯湖国家公园（TDNP）是位于曼查平原（西班牙）的一个独特的内陆湿地。它在国际上得到认可，并受到不同保护形式的保护，如生物圈保护区。然而，由于含水层的过度开采，这个生态系统正处于濒危状态，并面临失去保护形式的风险。我们的研究目的是通过 Landsat（5、7 和 8）和 Sentinel-2 图像分析 2000 年至 2021 年期间洪水区域的演变，并通过总水体表面的异常分析评估 TDNP 的状态。测试了几种水体指数，但 Sentinel-2 的 NDWI 指数（阈值-0.20）、Landsat-5 的 MNDWI 指数（阈值-0.15）和 Landsat-8 的 MNDWI 指数（阈值-0.25）在保护区范围内计算洪水表面的精度最高。在 2015-2021 年期间，我们比较了 Landsat-8 和 Sentinel-2 的性能，得到了 0.87 的 R 值，表明这两个传感器之间具有很高的一致性。我们的结果表明，在分析期间，洪水区域的变化很大，存在显著的峰值，最显著的是在 2010 年第二季度。自 2004 年第四季度至 2009 年第四季度，由于降水指数异常为负值，观察到的洪水区域最小。没有观察到水面异常与降水异常之间的显著相关性，而与流量和测压计异常之间的显著相关性则是中等的。这可以解释为，由于该湿地的用水复杂性，包括非法水井和地质异质性，导致了这种情况。
