Search Results (40)

Rice yield prediction at high spatial resolution is essential to support precision management and sustainable intensification in irrigated systems. While many remote sensing studies provide yield estimates at the field scale, pixel-level predictions are required to characterize within-field variability. This study assesses the potential of multitemporal Sentinel-2 imagery and machine learning to estimate rice yield at pixel level in the Albufera rice area (Valencia, Spain). Yield data from combine harvester maps were collected for ‘JSendra’ and ‘Bomba’ Japonica varieties over five growing seasons (2020–2024) and linked to 10 m Sentinel-2 bands in the visible, near-infrared (NIR) and short-wave infrared (SWIR) regions. Random Forest (RF) and XGBoost (XGB) models were trained with 2020–2023 data and independently validated in 2024. XGB systematically outperformed RF, achieving at 110 and 130 DAS (days after showing), R² values of 0.74 and 0.85 and RMSE values of 0.63 and 0.28 t·ha⁻¹ for ‘JSendra’ and ‘Bomba’. Prediction accuracy increased as the season progressed, and models using all spectral bands clearly outperformed configurations based only on spectral indices, confirming the dominant contribution of NIR reflectance. Spatial error analysis revealed errors at field edges and headlands, while central pixels were more accurately predicted. Overall, the proposed approach provides accurate, spatially explicit rice yield maps that capture within-field variability and support both end-of-season yield estimation and early season forecasting, enabling the identification of potentially low-yield zones to support targeted management decisions. Full article

This study first analyzes the ecotoxicity of bentazone (BTZ), an herbicide detected in the Albufera Natural Park. BTZ exhibits an EC₅₀ (5 days) towards Lactuca sativa of 900 mg L⁻¹, showing a hormetic effect. The toxic effects of a BTZ, $\mathrm{N}\mathrm{a}\mathrm{C}\mathrm{l}$, and ${\mathrm{N}\mathrm{a}}_2\mathrm{S}{\mathrm{O}}_4$ mixture are generally lower than the individual toxic effects considered additively. However, possible synergy on ecotoxicity was observed at 600 mg L⁻¹ of BTZ in the presence of 2.8 g L⁻¹ of ${\mathrm{N}\mathrm{a}}_2\mathrm{S}{\mathrm{O}}_4$ and 0.8 g L⁻¹ of $\mathrm{N}\mathrm{a}\mathrm{C}\mathrm{l}$. A statistical model was obtained to predict the ecotoxicity thresholds towards Lactuca sativa for combinations of the three compounds. In general, when the concentration of one compound increases, a lower concentration of the others is necessary for the mixture to be toxic. However, in the presence of $\mathrm{N}\mathrm{a}\mathrm{C}\mathrm{l}$, below 382 mg L⁻¹ of BTZ, the concentrations of both compounds need to be increased. This is attributable to the hormetic behavior of BTZ. This BTZ concentration decreases as the ${\mathrm{N}\mathrm{a}}_2\mathrm{S}{\mathrm{O}}_4$ concentration increases. Secondly, the effectiveness of electrooxidation and photoelectrooxidation processes to eliminate BTZ was studied. A ceramic anode made of Sb-${\mathrm{S}\mathrm{n}\mathrm{O}}_2$ and coated with a ${\mathrm{B}\mathrm{i}}_2{\mathrm{W}\mathrm{O}}_6$ photocatalyst was used. The degradation and mineralization degrees achieved using a mixture of 0.46 g L⁻¹ of $\mathrm{N}\mathrm{a}\mathrm{C}\mathrm{l}$ and 1.3 g L⁻¹ of ${\mathrm{N}\mathrm{a}}_2\mathrm{S}{\mathrm{O}}_4$ (like the Albufera lake conditions) show intermediate values between those achieved with pure electrolytes. Specifically, applying 0.6 A, they are very close to the maximum values achieved with pure $\mathrm{N}\mathrm{a}\mathrm{C}\mathrm{l}$. Moreover, the final effluent’s toxicity is significantly lower, especially when light is applied. Therefore, the photoelectrooxidation process applying 0.6 A with the mixed electrolyte is the most effective technique from the combined point of view of final degradation (90.9%), mineralization (62.4%), and toxicity. Full article

This study explores the use of remote sensing and machine learning (ML) for early detection of Pyricularia oryzae (rice blast) in ‘Bomba’ rice. Conducted in Spain’s Albufera Natural Park over four seasons (2021–2024), 94 fields were monitored using Sentinel-2 imagery and Topcon Yield Trakk data. Principal Component Analysis (PCA) identified key spectral bands (B03, B04, B05, B07, B08, B11) at early stages (35 and 55 DAS). Three ML classifiers—K-Nearest Neighbors (KNN), Random Forest (RF) and Support Vector Machines (SVMs)—were tested to categorize fields by yield-based infection levels. RF achieved the best performance (up to 94% Accuracy), showing high robustness across band combinations and dates. KNN was more input-sensitive, and SVM performed weakest. Integrating multispectral and multitemporal data enhanced accuracy. Overall, RF and remote sensing proved reliable tools for early disease detection, supporting Precision Agriculture and real-time pest management. Full article

Arundo donax L. (common reed), a highly invasive species in Mediterranean wetlands such as the Albufera Natural Park, poses significant ecological and management challenges. Using Landsat-5 and Sentinel-2 NDVI data, this study quantified changes in its coverage between 1996 and 2024. The results reveal a significant expansion, showing a decreasing trend (91.4 ha in 1996 to 62.5 ha in 2011; −31.6%) followed by a clear rebound (83.5 ha in 2024; +33.6%), especially in the southern shrublands of the lagoon. A Mann–Kendall analysis confirmed a significant decreasing trend during 1996–2011 and an increasing trend during 2011–2024 (p < 0.05). The results indicate that previous control efforts reduced A. donax cover but that the species has recolonised after 2011, likely due to discontinuous management. These dynamics emphasise that long-term monitoring is required. Management strategies must focus on targeting the rhizome and implementing long-term monitoring programmes spanning three to five years. The utilisation of remote sensing methodologies proved effective in the monitoring of coverage, thereby facilitating the development of remediation strategies. It is imperative that actions accord primacy to critical areas such as the south and canals, complemented by native restoration and enhanced inter-administrative coordination, with the communication of benefits such as flood risk reduction. A balanced approach is required that considers ecological objectives, risks, and socio-political aspects. Full article

The present study focuses on the extraordinary isolated high-level depression event that occurred on 29 October 2024 over the eastern Iberian Peninsula (Spain). The emphasis of the study is on the Turia and Magro river basins and the Albufera of Valencia lagoon basin, with particular attention given to the hydrological implications of the event in these areas. It is an established fact that episodes of intense precipitation give rise to flash floods. This recurrent phenomenon has significant economic and human impacts, and is particularly prominent in the Mediterranean region, including the Valencian Community (Eastern Spain). The estimation of peak flows at key sites in the basins was achieved through the utilization of an empirical methodological approach based on fieldwork to obtain the wetted cross-section of each site of analysis. Utilizing the existent official flow-measuring data network, an estimation was made of the average velocity of the water. The results indicate that flows in several locations exceeded the carrying capacity of the watercourses, leading to substantial flooding and overflows. The maximum estimated peak flow was determined to be 5678 m³ s⁻¹ in the Poyo ephemeral stream and 4198 m³ s⁻¹ in the Magro river. The results were validated using the Manning equation and related stream parameters (such as roughness and slope), obtaining a normalized root mean squared error of 3.62% and normalized mean absolute error of 2.26%. This analysis identified bottlenecks in the hydrographic network and emphasized the necessity to enhance detailed knowledge of the hydraulic capacity of watercourses. This helps with the purpose of flood risk management in the event of extreme future events accentuated by climate change. Full article

The Mediterranean coast is known for its great tourist attractions, concentration of population, and economic activities. Specifically, in the autonomous regions like Catalonia and Valencia, more than half of the population lives in coastal counties, and the population during the summer months increases due to the influx of tourists. Furthermore, in this stretch of coast, there are some areas of natural interest such as the Delta del Ebro or the Albufera, which are two of the most important wetland areas in the Mediterranean. However, according to studies by Day Today, the retreat of the coastline has increased in recent years, and this influences management of coastal territory both directly and indirectly, mostly harming all sectors with low levels, creating spaces with significant problems. It is for this reason that reporting on climate change and the impact on the coasts is assuming an important role in society, because they are essential tools for planning and management costs. In this thesis, the ground that would be affected by a +1 m, +2 m, and +3 m increase in average sea level, as simulated by the existing flood simulator, has been quantified. And a methodology has been developed for determining the vulnerability of the land based on flooding provided by terrain elevations, and each area studied was evaluated with different degrees of vulnerability: very high, high, moderate, or low. Finally, a first estimate has been made of economic loss that could involve a meter rise in the average sea level for Catalan beaches, and major damage to natural parks, urban areas, and major infrastructure has been identified. This study shows that there are nine areas with high vulnerability due to the low heights of their territory, and the majority of the flooded land is concentrated in the Ebro Delta and the Albufera, which jointly dominate the totals across scenarios. Full article

This article analyses the impact of urban sprawl on the Valencia Plain aquifer system from 1990 to 2018, focusing on land use and land cover (LULC) changes and their environmental implications. The study applies the Weighted Environmental Index (WEI), a composite indicator based on a functional landscape perspective, to quantify changes in the environmental value over time. The WEI combines CORINE Land Cover and World Settlement Footprint data to enhance spatial resolution and urban land detection. The results show a significant territorial transformation, with urban surfaces expanding by 70% and rainfed agricultural areas declining by over 59%. Consequently, the WEI decreased from 44.80 in 1990 to 40.68 in 2018, representing a 9.2% reduction in the environmental value. These changes threaten the sustainability of key ecosystems such as the Albufera Natural Park and indicate a reduced capacity to deliver ecosystem services, including aquifer recharging, biodiversity conservation, and climate regulation. The findings underscore the need for integrated land-use planning, the protection of peri-urban agricultural areas, and the implementation of nature-based solutions to counteract the environmental impacts of urban growth in Mediterranean metropolitan contexts. Full article

Anthropogenic activities represent a significant challenge to macrophyte conservation worldwide. Eutrophication, resulting from excessive nutrient inputs to aquatic ecosystems, is one of the main man-induced disturbances affecting the health of wetlands. Albufera of Valencia has experienced a hypertrophic and turbid state since the 1970s, with the consequent disappearance of macrophyte meadows and the predominance of phytoplankton. However, unique episodes of water clarity occurred in 2018 and 2022, leading to the reappearance of Myriophyllum spicatum and Najas marina, respectively. In the present study, the Normalized Difference Vegetation Index (NDVI) is used to monitor the emergence, growth, and disappearance of N. marina in 2022, as was previously done for M. spicatum. In November 2022, we obtained the maximum cover with 48.42 ha and began declining until March 2023. This methodology supports the potential of remote sensing in assessing the cover, density, and health of aquatic vegetation, while allowing us to examine the influence of water quality and quantity on this prominent phenomenon. After removing the outlier data, all variables except for suspended solids presented normal distribution. The results suggest that, by improving the water quality in the Albufera and maintaining an adequate ecological flow, managed by the competent authorities, the recovery of the macrophyte meadows that characterised this ecosystem more than five decades ago could be feasible. Full article

Background: The spread of antimicrobial resistance is a central public health problem. Wastewater treatment plants and impacted environments are well-known hotspots for antibiotic resistance. However, there is still limited knowledge regarding where antibiotic resistance genes (ARGs) acquire mobility. Method: In this study, we aimed to gather evidence on the seasonal patterns of ARG spread in two Mediterranean areas from NE and E of Spain (Ebro River and Ebro Delta, and Xúquer River and Albufera de València), correlating ARG presence, with special focus on the faecal bacteria Escherichia coli, with antibiotic residues and environmental conditions. The analytical methodology employed was based on a suspect screening approach, while a novel prioritisation approach for antibiotics was proposed to identify those areas more susceptible to the spread of ARG. Results: Our findings demonstrate that ARG levels in wastewater were similar across different seasons, although a greater diversity of ARGs was recorded in summer. We hypothesise that horizontal gene transfer among aquatic bacterial populations during the northeastern Mediterranean summer, when temperatures reach approximately 35~40 °C, could be a key driver of ARG dissemination. By contrast, the highest concentrations of antibiotics in winter samples, with temperatures around 5~10 °C, may promote the spread of microbial resistance. Conclusions: Our key findings highlight that water temperature and sunlight irradiation are crucial factors influencing antibiotic levels and microbial abundance, requiring further investigation in future studies. Full article

The Albufera of Valencia (Spain) is a representative case of pressure on water quality, which caused the hypertrophic state of the lake to completely change the ecosystem that once featured crystal clear waters. PerúSAT-1 is the first Peruvian remote sensing satellite developed for natural disaster monitoring. Its high spatial resolution makes it an ideal sensor for capturing highly detailed products, which are useful for a variety of applications. The ability to change its acquisition geometry allows for an increase in revisit time. The main objective of this study is to assess the potential of PerúSAT-1′s multispectral images to develop multi-parameter algorithms to evaluate the ecological state of the Albufera lagoon. During five field campaigns, samples were taken, and measurements of ecological indicators (chlorophyll-a, Secchi disk depth, total suspended matter, and its organic-inorganic fraction) were made. All possible combinations of two bands were obtained and subsequently correlated with the biophysical variables by fitting a linear regression between the field data and the band combinations. The equations for estimating all the water variables result in the following R² values: 0.76 for chlorophyll-a (NRMSE: 16%), 0.75 for Secchi disk depth (NRMSE: 15%), 0.84 for total suspended matter (NRMSE: 11%), 0.76 for the inorganic fraction (NRMSE: 15%), and 0.87 for the organic fraction (NRMSE: 9%). Finally, the equations were applied to the Albufera lagoon images to obtain thematic maps for all variables. Full article

In the context of climate change, extreme meteorological events such as severe storms produced by an isolated high-level atmospheric depression (known in Spanish as “Depresión Aislada en Niveles Altos”—DANA) are becoming increasingly frequent in the Mediterranean region, posing significant risks to ecosystems and human infrastructure. This study evaluates the impact of a DANA event in October 2024 on the water quality of Albufera Lake (Spain), a crucial Mediterranean wetland. A comprehensive evaluation was conducted by combining field data on physicochemical and biological parameters with satellite observations (Sentinel-2 and Landsat-8) to assess alterations before and after the event. Variables such as conductivity, nitrate, and total solids exhibited significant reductions immediately following the DANA, with conductivity decreasing by 82% compared to pre-event levels. These alterations signify a substantial renewal of the lake system driven by heavy rainfall and subsequent water releases. However, the lake demonstrated signs of recovery toward pre-event conditions over the following month. These results are consistent with previous findings, underscoring the system’s resilience and the necessity of periodic water releases to maintain ecological balance. The use of remote sensing tools effectively captured these dynamics, offering valuable insights for the long-term monitoring of water quality. This study highlights the urgent need for proactive management strategies to mitigate the effects of increasingly intense meteorological disturbances. Full article

The Albufera of Valencia is a hypereutrophic, oligohaline lagoon that has experienced significant changes in phytoplankton composition and state in recent decades due to human activities. These activities affect phytoplankton biomass and community structure, which are key indicators of ecosystem health. In this study, phytoplankton samples from the lagoon were analyzed to identify dominant groups and genera, and their seasonal cycles were determined using biovolume measurements with the Utermöhl method. Various environmental variables were also measured. Diversity was assessed using richness, equitability, and the Shannon–Wiener index. Canonical Correspondence Analysis (CCA) and Pearson correlation revealed that temperature and phosphorus significantly influence phytoplankton abundance. A species that exhibited seasonal abundance, resulting in a change in the lagoon’s color from green to brown, was identified. Water quality was assessed using the trophic state index, indicating that the lagoon is in poor condition and hyper-eutrophic. Cyanobacteria were the most dominant group, peaking in November, contrary to previous studies, followed by Chlorophyceae and Bacillariophyceae. Phytoplankton are vital bioindicators for assessing ecosystem health, underscoring the need for further research in this area. Full article

In the Mediterranean, urban and agricultural development has led to the degradation of coastal habitats and a decline in wetland biodiversity. L’Albufera de Valencia is a paradigmatic case-study, with intensive rice fields, scarcity of natural aquatic habitats, and an unfavorable conservation status. Since the 1990s, restoration efforts have been made in freshwater and brackish environments. In this study, long-, medium-, and short-term dynamics and ecological and functional traits were analyzed for waterbird communities. We found that restoration of these areas had facilitated the establishment of resilient communities with higher specialization and diversity than the rest of the protected area, including threatened species. Overall, restoration has improved population dynamics and ecological traits in L’Albufera compared to the surrounding hyper-eutrophic lagoon and rice fields. The findings reveal two complementary conservation paradoxes linked to ecological succession. Initial dynamics affected small, pioneer species of high conservation value, while larger species of conservation concern displaced them over time. Dynamics were influenced by body mass, with less competition in freshwater species. Notably, large waders and vegetation gleaners nesting in restored freshwater wetlands exhibited greater sensitivity to ecological succession, reversing regional declines. These paradoxes highlight the importance of increasing restoration efforts in various stages of succession to meet the ecological needs of threatened species. Full article

The Albufera of Valencia, a Mediterranean coastal lagoon, has experienced a shift to hypertrophic conditions over the past 40 years due to agricultural and urban-industrial pollution. From August 2023 to early 2024, the water of the lagoon turned reddish-brown. This change has been observed in the past, but never with this intensity or duration, which typically occurs during periods of drought. In this study, carotenoid concentrations were analyzed in relation to precipitation and temperature using field and remote sensing data from February 2016 to December 2023. In November 2023, samples showed unusually high concentrations of carotenoids. The study confirmed the effectiveness of a new algorithm for estimating carotenoids using Sentinel-2 imagery to complement chlorophyll-a data. Results showed that temperature and precipitation significantly influenced carotenoid/chlorophyll-a ratio, highlighting a climatic control of phytoplankton community structure. These results highlight the importance of long-term monitoring and conservation efforts to address climate change and human impacts. This research is a first step in using optical properties of lakes as an indicator of phytoplankton dynamics under environmental stress and warns of the potential for increased occurrence or persistence of such phenomena with future climate trends. Full article

In this paper, we investigated the monitoring and characterization of the pest Magnaporthe oryzae, known as rice blast, in the Bomba rice variety at the Albufera Natural Park, located in Valencia, Spain during the 2022 and 2023 seasons. Using reflectance data from different Sentinel-2 satellite bands, various vegetative indices were calculated for each year. Significant differences in reflectance in the visible (B4), infrared (B8), red-edge (B6 and B7), and SWIR (B11) bands were detected between healthy and unhealthy fields. Additionally, variations were observed in the vegetation indices, with RVI and IRECI standing out for their higher accuracy in identifying blast-affected plots compared to NDVI and NDRE. Early differences in band values, vegetative indices, and spectral signatures were observed between the unhealthy and healthy plots, allowing for the anticipation of control treatments, whose effectiveness relies on timely intervention. Full article