•We develop a water detection method which is particularly efficient in small water.•Graph convolutional network is innovatively used in image semantic segmentation.•Robustness of SG-waterNet is ...proven over urban, agricultural and mountainous scenes.
Small waterbodies sustain susceptible ecosystems and are influenced by variable dynamics associated with human activities and environmental disturbances. Although remote sensing has displayed efficiency in mapping surface waterbodies on a regular basis, the identification of small waterbodies such as ponds or irrigation ditches remains a challenge, as small waterbodies are often confused with other low-reflectivity surfaces. In this study, a superpixel-based graph convolutional network (GCN) for small waterbody extraction (SG-waterNet) is proposed. Specifically, the SG-waterNet method includes a new object-based representation of an image called a superpixel graph. The superpixel graph contains compact spectral and contextual information and can be exploited by the GCN. A deep GCN architecture is used to efficiently preserve small waterbody features and detect surface waterbodies with high completeness and correctness. We tested the proposed approach on a frequently used open-access Gaofen Image Dataset (GID) and Gaofen-1 image from Hubei Province in China (a total of 11,660 km2 for research). The extraction accuracy of SG-waterNet for small waterbodies (<2 ha) was between 84.31% and 89.77% at the five evaluation sites, and the method extracted waterbodies 300 m2 and larger with high confidence. Compared with six state-of-the-art methods, SG-waterNet exhibited significant sensitivity to small waterbodies (especially smaller than 100 m2) and detected small waterbody boundaries with the highest completeness and correctness. The average accuracy improvement achieved with SG-waterNet at the evaluation sites ranged from 11.10% to 13.87%. The proposed method is a significant advancement in small waterbody monitoring and can provide promising and practical solutions for real-world applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A plethora of research has focused on the biosafety of biodegradable plastics (BPs), including their microplastic formation and additives leaching; however, relatively fewer studies have explored ...biodegradation products. This study aims to investigate the biological effects and chemical features of degradation products from three kinds of BPs, namely polyglycolic acid (PGA), poly (butylene adipate-co-terephthalate) (PBAT), and the blends of PGA/PBAT without the addition of additives, in a simulated small waterbody environment with extracted soil solution for three months. Results showed that exposure to the whole degradation remnants of three BPs had no lethal effects on zebrafish at the current BP environmental concentrations (from 0.24 to 12.72 mg plastic/L) in small waterbodies. However, from the calculated BPs environmental concentrations (from 0.57 to 43.82 mg plastic/L) in 2026, PGA and PGA/PBAT blends may cause adverse effects on the cardiovascular system such as heartbeat rate suppression in zebrafish embryos, and also lead to reduced body length and pericardial edema and spinal curvature in fish larvae. We further qualitatively analyzed the composition of degradation products, and quantitatively measured four dominant degradation monomers (glycolic acid (GA), adipic acid (A), 1,4-butanediol (B), and terephthalic acid (T)) in the degradation remnants. It was found that the observed toxicities were probably due to the presence of GA, A, and T monomers, and their concentrations can reach 0.776, 0.034, and 0.6 mg/L under the calculated future scenario, respectively. It is worth mentioning that either GA or T monomers at the above concentrations were found to cause suppressed heartbeat rate in zebrafish embryos. Collectively, though the degradation products of BPs are temporarily safe at current environmental concentrations, they may lead to non-negligible toxicity with increasing production and continual improper recycling and/or BP waste management.
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•Three-month degradation products from BPs without additives were prepared.•The whole degradation products of three pure BPs had no lethal effects on zebrafish embryos and larvae.•Future concentrations of BP degradation products can alter fish heart rate and body length.•Degradation products' toxicity was likely driven by glycolic and terephthalic acids.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The variations in the water area and water level of Cheonji, the caldera lake of Baekdu Mountain, serve as reliable indicators of volcanic precursors. However, the geographical and spatial features ...of Baekdusan make it impossible to directly observe the water area and water level. Therefore, it is crucial to rely on remote sensing data for monitoring purposes. Optical satellite imagery employs different spectral bands to accurately delineate the boundaries between water bodies and non-water bodies. Conventional methods for classifying water bodies using optical satellite images are significantly influenced by the surrounding environment, including factors like terrain and shadows. As a result, these methods often misclassify the boundaries. To address these limitations, deep learning techniques have been employed in recent times. Hence, this study aimed to create an AI dataset using Landsat-5/-7/-8 and Sentinel-2 optical satellite images to accurately detect the water body area and water level of Cheonji lake. By utilizing deep learning methods on the dataset, it is reasonable to consistently observe the area and level of water in Cheonji lake. Furthermore, by integrating additional volcanic precursor monitoring factors, a more accurate volcano monitoring system can be established.
The fluctuations in the area and level of Cheonji in Baekdu Mountain have been employed as significant indicators of volcanic activity. Monitoring these changes directly in the field is challenging ...because of the geographical and spatial features of Baekdu Mountain. Therefore, remote sensing technology is crucial. Synthetic aperture radar utilizes high-transmittance microwaves to directly emit and detect the backscattering from objects. This weatherproof approach allows monitoring in every climate. Additionally, it can accurately differentiate between water bodies and land based on their distinct roughness and permittivity characteristics. Therefore, satellite radar is highly suitable for monitoring the water area of Cheonji. The existing algorithms for classifying water bodies using satellite radar images are significantly impacted by speckle noise and shadows, resulting in frequent misclassification. Deep learning techniques are being utilized in algorithms to accurately compute the area and boundary of interest in an image, surpassing the capabilities of previous algorithms. This study involved the creation of an AI dataset specifically designed for detecting water bodies in Cheonji. The dataset was constructed using satellite radar images from TerraSAR-X, Sentinel-1, and ALOS-2 PALSAR-2. The primary objective was to accurately detect the area and level of water bodies. Applying the dataset of this study to deep learning techniques for ongoing monitoring of the water bodies and water levels of Cheonji is anticipated to significantly contribute to a systematic method for monitoring and forecasting volcanic activity in Baekdu Mountain.
The urban heat island (UHI) phenomenon represents a major public health issue and has received great attention due to rapid urbanisation. Blue spaces have long been considered a possible mitigation ...strategy to ameliorate the UHI. However, our knowledge regarding the interaction of waterbodies with their urban surroundings is still limited. This review attempts through a comparative analysis of the available literature to examine the thermal effects of static blue spaces on the urban climate. Remote sensing studies are the most common approach analysed in this review but there is a clear disparity between the cooling potentials reported by remote sensing as opposed to field measurements or numerical simulations, likely due to a lack of nocturnal measurements, when warming due to thermal inertia can occur and consideration of the latent heat flux. The size and shape of blue spaces are shown to be important variables for the cooling achieved in urban settings but there is no consensus in the literature. This is likely due to the different locations and climates of the studies, it can be hypothesised that in locations with an even distribution of wind directions a rounder waterbody is more effective while in locations where wind direction is more uniform an elongated waterbody aligned to the wind is more effective due to the increased fetch. From the analysis of the literature, it is clear that there is still a distinct knowledge gap regarding the physical interpretation of waterbodies' contribution to the urban climate. There is also a current lack of information about the diurnal and seasonal variability of the various structures and processes. There is evidence, however, that the comfort achieved by sensible cooling can be offset by the increased water vapour content and that during the night blue spaces may actually exacerbate the UHI, reducing urban thermal comfort.
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•The influence of urban blue space on urban canopy/boundary-layer temperatures•The cooling effect of blue spaces varies with time of day, the season and location.•Remote sensing studies tend to overestimate the cooling potential of blue space.•Blue spaces may not provide cooling all day long and may provide warming at night.•The influence of geometry and diversity of urban blue spaces requires more research.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Cooling intensity of all types of waterbody patches were quantified and compared.•The patch size of waterbody was the dominant factor of cooling intensity.•Local socioeconomic development strongly ...impacted the cooling effect of waterbody.•Threshold value of cooling efficiency of different waterbodies were identified.
Climatic warming and urbanization have exacerbated urban heat island (UHI) effect globally. Waterbodies have significant cooling effect while the current UHI mitigation researches mostly focus on green spaces. Although the cooling effect of waterbodies has been highlighted and measured in previous studies, the impact of local socioeconomic development surrounding the waterbodies remains unclear. The scarcity of land resource in the city has also posed urgent need to explore cooling efficiency of waterbody patch size. Highly urbanized and densely scattered with waterbody, the Pearl River Delta (PRD) urban agglomeration has suffered severe UHI effect. Taking four PRD cities as the case study area, this study analyzed the impact of local socioeconomic development on the daytime cooling intensity of waterbodies, and identified the dominant impact factor as well as the threshold value of efficiency (TVoE) in diversely developed areas. The results showed that the cooling intensity of waterbodies had obvious spatial heterogeneity with an average of 1.1 °C and a maximum of 5.54 °C, which was dominated by patch size and strongly affected by local socioeconomic development. The mean cooling intensity increased along with the increasing of local socioeconomic development, and the TVoEs of waterbody patch size were 0.49 ha, 0.55 ha and 0.70 ha in such three levels of local socioeconomic development as low, medium and high, respectively. The results can provide quantitative guidance for blue landscape planning in regard to UHI effect mitigation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
For the spatiotemporal analysis of water resources and disasters, water body detection using satellite imagery is crucial. Recently, AI-based methods have been widely employed in water body detection ...using satellite imagery. To use these AI techniques, a substantial amount of training data is required. When creating training data for water body detection, optical imagery and synthetic aperture radar (SAR) imagery have their respective strengths and weaknesses. To use the advantages of both, this study proposes a water body detection method through the fusion of optical and SAR imagery. The results of the proposed model show an Intersection over Union of 0.612 and an F1 score of 0.759, which is better compared to using either optical or SAR imagery alone. This research presents a method that can easily generate a large amount of water body data, making it promising for use as AI training data for water body detection.
More than 20 years after the Water Framework Directive was adopted, there are still major gaps in the sanitary status of small rivers and waterbodies at the head of basins. These small streams supply ...water to a large number of wetlands that support a rich biodiversity. Many of these waterbodies are fishponds whose production is destined for human consumption or for the restocking of other aquatic environments. However, these ecosystems are exposed to contaminants, including pesticides and their transformation products. This work aims to provide information on the distribution, diversity, and concentrations of agricultural contaminants in abiotic and biotic compartments from a fishpond located at the head of watersheds. A total of 20 pesticides and 20 transformation products were analyzed by HPLC-ESI-MS/MS in water and sediment sampled monthly throughout a fish production cycle, and in three fish species at the beginning and end of the cycle.
The highest mean concentrations were found for metazachlor-OXA (519.48 ± 56.52 ng.L−1) in water and benzamide (4.23 ± 0.17 ng g−1 dry wt.) in sediment. Up to 20 contaminants were detected per water sample and 26 per sediment sample. The transformation products of atrazine (banned in Europe since 2003 but still widely used in other parts of the world), flufenacet, imidacloprid (banned in France since 2018), metazachlor, and metolachlor were more concentrated than their parent compounds. Fewer contaminants were detected in fish and principally prosulfocarb accumulated in organisms during the cycle.
Our work brings innovative data on the contamination of small waterbodies located at the head of a basin. The transformation products with the highest frequency of occurrence and concentrations should be prioritized for further environmental monitoring studies, and specific toxicity thresholds should be defined. Few contaminants were found in fish, but the results challenge the widely use of prosulfocarb.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study aims to provide a comprehensive understanding of the role of urban waterbodies in avian ecology, which is instructive for both biodiversity conservation and urban planning. Based on bird ...surveys conducted in 41 urban parks in Beijing during the breeding and wintering seasons of 2018–2019, and using standardized regression analyses, we identified the specific effects of waterbody attributes on the full avian community and forest bird guilds. We assessed this at multiple spatial scales, first within the focal parks, and then within buffer zones with radius of 200 m and 1000 m. We found that waterbodies can serve as avian diversity “hotspots” in the urban landscape. More specifically, they support avian diversity in the following ways: (1) Parks with waterbodies maintain a higher number of bird species than parks without waterbodies during the breeding season and attract resident forest birds during the wintering season. (2) When not frozen, waterbodies inside and outside parks contribute equally to resident forest bird species richness, while more individuals were attracted by waterbodies within neighborhoods. (3) In parks without waterbodies, the number of forest bird species significantly increases with the number of waterbody patches within neighborhoods, while the corresponding relationship for parks with waterbodies is insignificant. These findings suggest a preference for habitats nearby waterbodies among forest birds residing highly urbanized areas. This study provides new insights into avian ecology in urban landscapes and scientific support for the idea that creating and maintaining urban waterbodies can conserve biodiversity.
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•Urban parks with waterbodies are more efficient in maintaining avian diversity.•Waterbodies have similar importance for forest birds of different physical statuses.•Waterbodies within and outside a given park are competitive in attracting birds.•Urban forest birds prefer habitats near waterbody patches.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
