Permanent Water Bodies Research Articles

Cutting-edge approaches for judging surface water dynamics in semi-arid environments: Integrating landsat 8 OLI/TIRS and HYDROSAM model

This research addresses the critical need to assess surface water dynamics in semi-arid regions of Andhra Pradesh, India, by using advanced Spectral Indices for hydrological applications and methodologies. It aims to answer how remote sensing data from Landsat 8 OLI/TIRS can be effectively used to monitor and classify surface water bodies. The study applies indices such as Normalized Difference Water Index (NDWI), Modified Normalized Difference Water Index (MNDWI), Normalized Difference Thermal Index (NDTI), and Water Ratio Index (WRI). Additionally, the Weighted Composite Index (WCI) and Normalized Composite Index (NCI) are integrated with Principal Component Analysis (PCA) for multi-criteria decision making. The HYDROSAM model successfully classifies and maps various categories of surface water bodies, including non-water features (53.62%), urban water zones (37.89%), seasonal water bodies (4.32%), transitional zones (2.17%), permanent water bodies (1.05%), and river bodies (0.95%). The resultant map was validated using the AUC-ROC curve, achieving an AUC of 0.820, indicating a high level of accuracy. This methodology provides a nuanced understanding of water resource distribution and availability in the region. The findings demonstrate the robustness and reliability of the HYDROSAM model in accurately assessing surface water characteristics, thereby providing critical insights for informed water resource management, strategic land-use planning, and effective ecological conservation. This innovative methodology not only fosters sustainable water resource management in semi-arid regions but also sets a precedent for advancing research in similar ecosystems globally.

Diversity of bacterial communities in wetlands of Calakmul Biosphere Reserve: a comparative analysis between conserved and semi-urbanized zones in pre-Mayan Train era

BackgroundThe Calakmul Biosphere Reserve (CBR) is known for its rich animal and plant biodiversity, yet its microbial communities remain largely unknown. The reserve does not possess permanent bodies of water; nevertheless, seasonal depressions associated with fractures create wetlands, known locally as aguadas. Given the recent construction of the Maya train that crosses the CRB, it is essential to assess the biodiversity of its microorganisms and recognize their potential as a valuable source of goods. This evaluation is pivotal in mitigating potential mismanagement of the forest ecosystem. To enhance comprehension of microbial communities, we characterized the microbiota in three different wetlands. Ag-UD1 and Ag-UD2 wetlands are located in a zone without human disturbances, while the third, Ag-SU3, is in a semi-urbanized zone. Sampling was carried out over three years (2017, 2018, and 2019), enabling the monitoring of spatiotemporal variations in bacterial community diversity. The characterization of microbiome composition was conducted using 16S rRNA metabarcoding. Concurrently, the genomic potential of select samples was examined through shotgun metagenomics.ResultsStatistical analysis of alpha and beta diversity indices showed significant differences among the bacterial communities found in undisturbed sites Ag-UD1 and Ag-UD2 compared to Ag-SU3. However, no significant differences were observed among sites belonging to the undisturbed area. Furthermore, a comparative analysis at the zone level reveals substantial divergence among the communities, indicating that the geographic location of the samples significantly influences these patterns. The bacterial communities in the CBR wetlands predominantly consist of genera from phyla Actinobacteria, Acidobacteria, and Proteobacteria.ConclusionThis characterization has identified the composition of microbial communities and provided the initial overview of the metabolic capacities of the microbiomes inhabiting the aguadas across diverse conservation zones. The three sites exhibit distinct microbial compositions, suggesting that variables such as chemical composition, natural and anthropogenic disturbances, vegetation, and fauna may play a pivotal role in determining the microbial structure of the aguadas. This study establishes a foundational baseline for evaluating the impact of climatic factors and human interventions on critical environments such as wetlands.

Water availability and biological interactions shape amphibian abundance and diversity in Mediterranean temporary rivers

Amphibians, the most threatened vertebrates globally, face risks due to climate change, habitat loss, and fragmentation. Their sensitivity to environmental changes highlights their importance as ecological indicators. Temporary rivers, influenced by geological, climatic, and anthropogenic factors, play a critical role in shaping biodiversity and community structure. Some species of amphibians may be adapted to these temporary waters, a fact reflected in their life cycles and various biological traits. However, to develop effective conservation strategies for amphibians, it is essential to address the knowledge gaps surrounding the complex interactions between biological dynamics and fluvial habitat conditions. In this study, we investigated how trophic interactions between amphibians and other aquatic organisms (diatoms, macroinvertebrates, and fish), coupled with environmental factors (water availability and riparian structure), can affect amphibian abundance and diversity in temporary rivers. The study was conducted in a Mediterranean river network located in Sant Llorenç del Munt i l'Obac Natural Park (Catalonia, Spain). Our expectations were that habitats suitable for egg deposition, lacking predators (e.g. tadpole-predators and fish), and abundant in food sources would likely support higher amphibian abundance and diversity. However, water availability was identified as a crucial factor shaping abundance and diversity in the studied amphibian communities, even if it correlated with fish presence, and especially impacting amphibian species usually linked to permanent water bodies. Concerning biotic interactions, while our results suggested that amphibian populations in temporary rivers are more dependent on top-down than bottom-up interactions, the presence of aquatic predators was not as conclusive as expected, suggesting that in temporary rivers the fish-avoiding amphibian species can survive using microhabitats or breeding opportunities linked to natural river dynamics. Overall, our findings highlight the importance of considering multi-trophic interactions, hydroperiod and habitat heterogeneity in temporary river ecosystems for effective amphibian conservation.

The role of species interactions in shaping the geographic pattern of ungulate abundance across African savannah

Macroecologists traditionally emphasized the role of environmental variables for predicting species distribution and abundance at large scale. While biotic factors have been increasingly recognized as important at macroecological scales, producing valuable biotic variables remains challenging and rarely tested. Capitalizing on the wealth of population density estimates available for African savannah ungulates, here we modeled species average population density at 100 × 100 km as a function of both environmental variables and proxies of biotic interactions (competition and predation) and estimated their relative contribution. We fitted a linear mixed effect model on 1043 population density estimates for 63 species of ungulates using Bayesian inference and estimated the percentage of total variance explained by environmental, anthropogenic, and biotic interactions variables. Environmental and anthropogenic variables were the main drivers of ungulate population density, with NDVI, Distance to permanent water bodies and Human population density showing the highest contribution to the variance. Nonetheless, biotic interactions altogether contributed to a quarter of the variance explained, with predation and competition having a negative effect on species density. Despite the limitations of modelling biotic interactions in macroecological studies, proxies of biotic interactions can enhance our understanding of biological patterns at broad spatial scales, uncovering novel predictors as well as enhancing the predictive power of large-scale models.

A revisit to the Early Pliocene site of Abla (Guadix-Baza Basin, southern Spain)

The Guadix-Baza Basin (southern Spain) displays one of the best continental records from the Late Miocene to the Middle Pleistocene in western Europe, with many localities of fossil small mammals in a quite complete and continuous stratigraphic sequence. The Late Miocene continentalization of the Guadix-Baza Basin was firstly mentioned in the 1980s based on the presumed presence of Hipparion gromovae granatensis at the site of Abla (Almería province). Subsequent discoveries of late Turolian deposits confirmed the Late Miocene continentalization of the basin. The interest in the Abla site led to a second sampling campaign to look for microvertebrate fossils, which proved successful. In this paper, a complete taxonomic study of the novel microvertebrate fauna from Abla is presented, providing updated information on the age of the locality. Representatives of the vertebrate families Cyprinidae, Alytidae, Anguidae, Soricidae, Cricetidae, and Muridae have been identified. The presence of Stephanomys specimens exceeding the size of latest Miocene-earliest Pliocene species allows us to correlate the Abla site with the Early Pliocene (Ruscinian), a younger age than initially stated. A qualitative paleoecological interpretation based on the herpetofauna suggests the dominance of open environments with presence of permanent water bodies during the deposition of the Abla site, under warmer and more humid climate conditions than today in the Guadix-Baza Basin. A revision of the Hipparion remains from this locality showed that the sample is closer to Hipparion fissurae than to the initially assigned species.

Cropland inundation mapping in a mountain dominated region based on multi-resolution remotely sensed imagery and active learning for semantic segmentation

Accurate and timely mapping of cropland inundated area is critical to loss assessment and recovery plan development. However, existing methods for cropland inundation mapping using Synthetic Aperture Radar (SAR) imagery are primarily designed for plain regions and may not be suitable for mountainous regions. The complex rugged terrain at large scale present challenges such as significant noise from radar shadows, smooth surfaces, floodplains, and permanent water bodies. To remove these noise for effectively mapping of cropland inundation, this study proposes a robust two-stage framework integrating the multi-resolution remotely sensed imageries and semantic segmentation method. First, active learning for cropland extraction is performed with Google Very-High-Resolution (VHR) imagery and Segformer model. Second, the cropland inundation area is obtained using marker-controlled watershed segmentation (MCW) on Sentinel-1 SAR imagery with area-of-interest (AOI) filtering. Results show that the extracted cropland mask are superior to six public cropland data products including ESA, ESRI, FCS30, FROM, GL30, and SLOPE. In addition, with AOI filtering, the F-score of the potential flood identification using MCW was increased from 0.685 to 0.828. At last, the monthly cropland inundation caused by intense rainfall varied approximately from 6.6 km2 to 436.1 km2 during monsoon season of 2017–2022 in Guangdong. Our approach offers a fast and feasible solution for mapping cropland inundation in large and complex mountainous regions, without requiring extensive parameter tuning or additional data.

Влияние фосфорсодержащих пестицидов на ферментативную активность и множественные формы кислой фосфатазы живородки речной (Viviparus viviparus L.)

Organophosphate pesticides are used in agriculture and for treating landscape and park areas due to their high efficiency and economic availability, and therefore they are potential toxicants in water bodies. Broad-spectrum systemic herbicide (Glyphosate) and an organophosphorus insecticide (Malathion) have been studied against the freshwater mollusks (Viviparus viviparus L.), widespread in permanent water bodies of the European part of Russia and Siberia. Changes in the activity and composition of multiple forms of acid phosphatase (AcP) were revealed in the hepatopan creas of mollusks under the influence of high doses of glyphosate and malathion in an acute toxicological experiment (96 hours). In both cases, an increase in enzyme activity is observed, but the cholinomimetic malathion is significantly more active than glyphosate, the neurotropic activity of which is unknown. It was shown that the increase in activity in the experimental groups of mollusks is associated with the appearance of new multiple forms of acid phosphatase, which persist throughout the experiment. Multiple form of AсP with low relative electrophoretic mobility revealed as an effect of glyphosate and malathion. In addition, in mollusks exposed to malathion, a multiple form of the enzyme with an average electrophoretic mobility was detected. The composition of multiple forms of acid phosphatase in mollusks of the control group did not change during the exposure. The results indicate the formation of nonspecific adaptations in response to organophosphate pesticides and confirm that acid phosphatase can be an indicator of toxic effects in environmental and biochemical monitoring of freshwater pollution.

Small dams drive Anopheles abundance during the dry season in a high malaria burden area of Malawi.

This study explores the influence of small dams on the exposure to malaria vectors during the dry season in Kasungu district, Malawi, an area recently identified as high priority for malaria interventions by the National Malaria Control Programme. Small dam impoundments provide communities with a continuous supply of water for domestic and agricultural activities across sub-Saharan Africa and are considered vital to food security and climate change resilience. However, these permanent water bodies also create ideal breeding sites for mosquitoes in typically arid landscapes. The study focuses on a specific dam impoundment and its vicinity, aiming to assess its spatial and temporal influence on indoor vector densities. From May to August 2021, CDC light traps were used to measure indoor mosquito densities for two consecutive nights per month in three communities located at increasing distances from the dam (0, ~1 and ~2 km). Simultaneously, drone imagery was captured for each community, enabling the identification of additional standing water within approximately 400 m of selected households. Larval sampling was carried out within the impoundment periphery and in additional water bodies identified in the drone imagery. Generalised linear mixed models (GLMMs) were employed to analyse the indoor Anopheles abundance data, estimating the effects of household structure (open/closed eaves), month, temperature and water proximity on malaria vector exposure. Throughout 685 trapping nights, a total of 1256 mosquitoes were captured, with 33% (412) being female Anopheles. Among these, 91% were morphologically identified as Anopheles funestus s.l., and 5% as Anopheles gambiae s.l. Catches progressively decline in each consecutive trapping month as the environment became drier. This decline was much slower in Malangano, the community next to the dam, with abundance being notably higher in June and July. Further, the majority of An. gambiae s.l. were caught in May, with none identified in July and August. Anopheles larvae were found both in the impoundment and other smaller water bodies such as irrigation wells in each survey month; however, the presence of these smaller water bodies did not have a significant impact on adult female mosquito catches in the GLMM. The study concludes that proximity to the dam impoundment was the primary driver of differences between survey communities with the abundance in Chikhombwe (~1 km away) and Chiponde (~2 km away) being 0.35 (95% confidence interval [CI], 0.19-0.66) and 0.28 (95% CI, 0.16-0.47) lower than Malangano, respectively, after adjusting for other factors. These findings underscore the importance of targeted interventions, such as larval source management or housing improvements, near small dams to mitigate malaria transmission risks during the dry season. Further research is needed to develop cost-effective strategies for vector control within and around these impoundments.

Tracking dynamics characteristics of tidal flats using landsat time series and Google Earth Engine cloud platform

Tidal flats serve as vital spatial resources within coastal wetlands and play crucial roles in biological habitat preservation, environmental conservation, and human development. However, accurately delineating their extent from instantaneous remote sensing images poses challenges, owing to the dynamic interplay between seawater and land. Therefore, this study utilized the consistency of remote sensing satellites and developed a multi-feature decision approach based on the long-term remote sensing datasets and the Google Earth Engine (GEE) cloud platform for determining the spatial extent, classifying types, and mapping the spatial-temporal distribution of the tidal flats. Initially, a multi-temporal image stack was compiled from the filtered remote sensing images. Subsequently, the modified normalized difference water index (MNDWI) and automated water extraction index (AWEI) were calculated to establish the maximum and minimum water surfaces using the extreme value composite algorithm (EVCA). The Otsu algorithm and spatial overlay analysis method were then utilized to accurately delineate the spatial extent of the tidal flats. Additionally, the Normalized Difference Vegetation Index (NDVI) was utilized to accurately identify tidal flat types. Post-processing involves elevation data and mathematical morphological methods to mitigate the impact of permanent water bodies. Finally, the accuracy of the extracted spatial extent and types of tidal flats was evaluated. The efficacy and practicality of the proposed method were validated using the Zhoushan Archipelago and Landsat time series in China. The results revealed the following: (1) the acquired tidal flat information exhibited evident boundaries and accurate types, achieving an overall accuracy (OA) of 94.80 % and a Kappa coefficient of 0.89; (2) the area of tidal flats in the Zhoushan Archipelago increased from 2,182.19 ha in 1985 to 3,761.21 ha in 2020, with an average annual increase of 45.12 ha and an average annual increase rate of 1.57 %; and (3) over 35 periods, the area transformed from other land types to tidal flats amounted to 2,895.74 ha, while the area converted from tidal flats to other land types totaled 1,651.90 ha. The three islands with the most rapid growth in tidal flat area were Liuheng Island, Dachangtu Island, and Daishan Island, with changes of 675.68 ha, 380.47 ha, and 362.63 ha, respectively. This method can offer an automated, swift, and accurate approach for tidal flat extraction, demonstrating high precision and practical effectiveness, thereby providing robust technical support for coastal resource surveys.

Issues of Water Resources in Saudi Arabia: Past, Present, and Future

The present paper addresses a comprehensive historical assessment of water consumption, demand, and supply in Saudi Arabia, along with future projections regarding water balance, in terms of demand and supply by source in various sectors. Being an arid region, Saudi Arabia experiences scorching heat, low precipitation, a high rate of potential evaporation, and the absence of permanent water bodies over the territory. Groundwater contributes almost 61% of total available water, while the recharge rate is negligible. However, few widyan (ephemeral streams) systems exists to satisfy water demand, which could contribute to approximately one year of domestic water consumption if managed efficiently. The study also predicts water consumption scenarios for the next three consecutive development plans, i.e., the 10th plan (2015–2019), 11th plan (2020–2024), and 12th plan (2025–2029). The analysis shows that water consumption may decline significantly in the future, if the present rate of decline continues. Scenario I, if the current rate is assumed, provides a decrease in consumption of 14.36, 12.66, and 11.15 BCM for 10th, 11th, and 12th plans, respectively. Moreover, the domestic and industrial sectors will consume more water in the future. In the same way, scenarios II and III represent a decline in total water consumption, along with that of agriculture, while domestic and industrial water usage would increase, thus improving environmental sustainability.

‘Kesho’ Scenario Development for Supporting Water-Energy Food Security under Future Conditions in Zanzibar

Social-ecological interactions mediate water–energy–food security in small developing islands, but community-scale insights are underrepresented in nexus research. These interactions are dynamic in their response to environmental and anthropogenic pressures and need to be understood to inform sustainable land use planning into the future. This study centered on bringing together diverse stakeholders to explore water–energy–food futures using the “Kesho” (meaning “tomorrow” in Kiswahili) scenario tool for two of the largest islands that comprise the Zanzibar Archipelago. The methodology comprised four core stages: (1) exploration of how past drivers of change impacted water–energy–food security; (2) modeling of a Business as Usual Scenario for land cover change; (3) narrative development to describe alternative futures for 2030 based on themes developed at the community scale; and (4) predictions about how narratives would shape land cover and its implications for the nexus. These results were used to model alternate land cover scenarios in TerrSet IDRISI (v. 18.31) and produce visual representations of expected change. Findings demonstrated that deforestation, saltwater incursion, and a reduction in permanent waterbodies were projected by 2030 in a Business as Usual Scenario. Three alternative scenario narratives were developed, these included Adaptation, Ecosystem Management, and Settlement Planning. The results demonstrate that the effectiveness of actions under the scenario options differ between the islands, indicating the importance of understanding the suitability of national policies across considered scales. Synergies across the alternative scenario narratives also emerged, including integrated approaches for managing environmental change, community participation in decision making, effective protection of forests, cultural sensitivity to settlement planning, and poverty alleviation. These synergies could be used to plan strategic action towards effectively strengthening water–energy–food security in Zanzibar.

Cropland Inundation Mapping in Rugged Terrain Using Sentinel-1 and Google Earth Imagery: A Case Study of 2022 Flood Event in Fujian Provinces

South China is dominated by mountainous agriculture and croplands that are at risk of flood disasters, posing a great threat to food security. Synthetic aperture radar (SAR) has the advantage of being all-weather, with the ability to penetrate clouds and monitor cropland inundation information. However, SAR data may be interfered with by noise, i.e., radar shadows and permanent water bodies. Existing cropland data derived from open-access landcover data are not accurate enough to mask out these noises mainly due to insufficient spatial resolution. This study proposed a method that extracted cropland inundation with a high spatial resolution cropland mask. First, the Proportional–Integral–Derivative Network (PIDNet) was applied to the sub-meter-level imagery to identify cropland areas. Then, Sentinel-1 dual-polarized water index (SDWI) and change detection (CD) were used to identify flood area from open water bodies. A case study was conducted in Fujian province, China, which endured several heavy rainfalls in summer 2022. The result of the Intersection over Union (IoU) of the extracted cropland data reached 89.38%, and the F1-score of cropland inundation achieved 82.35%. The proposed method provides support for agricultural disaster assessment and disaster emergency monitoring.

Characterization of larval habitats of Anopheles (Nyssorhynchus) darlingi and associated species in malaria areas in western Brazilian Amazon.

Anopheles darlingi is the most efficient vector of malaria parasites in the Neotropics. Nevertheless, the specificities of its larval habitats are still poorly known. Characterize permanent larval habitats, and population dynamics of An. darlingi and other potential vectors in relation to climate, physicochemical variables, insect fauna and malaria cases. A 14-month longitudinal study was conducted in Porto Velho, Rondônia, western Brazilian Amazon. Monthly, 21 permanent water bodies were sampled. Immature anophelines and associated fauna were collected, physicochemical characteristics, and climate variables were recorded and analyzed. Five types of habitats were identified: lagoon, stream, stream combined with lagoon, stream combined with dam, and fishpond. A total of 60,927 anophelines were collected. The most abundant species in all habitats were Anopheles braziliensis and An. darlingi. The highest density was found in the lagoon, while streams had the highest species richness. Abundance was higher during the transition period wet-dry season. There was a lag of respectively four and five months between the peak of rainfall and the Madeira River level and the highest abundance of An. darlingi larvae, which were positively correlated with habitats partially shaded, pH close to neutrality, increase dissolved oxygen and sulphates. The present study provides data on key factors defining permanent larval habitats for the surveillance of An. darlingi and other potential vectors as well as a log-linear Negative Binomial model based on immature mosquito abundance and climate variables to predict the increase in the number of malaria cases.

An Enhanced Dual-Stream Network Using Multi-Source Remote Sensing Imagery for Water Body Segmentation

Accurate surface water mapping is crucial for rationalizing water resource utilization and maintaining ecosystem sustainability. However, the diverse shapes and scales of water bodies pose challenges in automatically extracting them from remote sensing images. Existing methods suffer from inaccurate lake boundary extraction, inconsistent results, and failure to detect small rivers. In this study, we propose a dual-stream parallel feature aggregation network to address these limitations. Our network effectively combines global information interaction from the Swin Transformer network with deep local information integration from Convolutional Neural Networks (CNNs). Moreover, we introduce a deformable convolution-based attention mechanism module (D-CBAM) that adaptively adjusts receptive field size and shape, highlights important channels in feature maps automatically, and enhances the expressive ability of our network. Additionally, we incorporate a Feature Pyramid Attention (FPA) module during the advanced coding stage for multi-scale feature learning to improve segmentation accuracy for small water bodies. To verify the effectiveness of our method, we chose the Yellow River Basin in China as the research area and used Sentinel-2 and Sentinel-1 satellite images as well as manually labelling samples to construct a dataset. On this dataset, our method achieves a 93.7% F1 score, which is a significant improvement compared with other methods. Finally, we use the proposed method to map the seasonal and permanent water bodies in the Yellow River Basin in 2021 and compare it with existing water bodies. The results show that our method has certain advantages in mapping large-scale water bodies, which not only ensures the overall integrity but also retains local details.

A contrarian growth: The spatiotemporal dynamics of open-surface water bodies on the northern slope of Kunlun Mountains

Identifying and monitoring open-surface water bodies are significant for understanding regional water resource distribution and evolving trends. This understanding carries profound value for comprehensively assessing the effects of climate change and human social activities on water resources and maintaining water security. This study pioneers’ improvements in surface water detection rules with the central aim of constructing a Method with Enhanced Impurity Control, specifically tailored for complex environmental scenarios (OA = 98.97 % ± 0.06). This is achieved by incorporating intricate exponential constraints and targeted data masks. Our analysis is grounded in the examination of 21,709 preprocessed high-quality images, covering the period from 1990 to 2021 across the northern slope of the Kunlun Mountains. Through this comprehensive study, we have gleaned insightful results regarding the spatiotemporal dynamics of open-surface water bodies. In the past 32 years, the surface water body area on the northern slope of the Kunlun Mountains has exhibited a significantly increasing trend. Specifically, the size of permanent water bodies expanded by 71.03 % (with a 95 % confidence interval: ± 27.73 %), while the area of seasonal water bodies grew by a substantial 170.63 % (with a 95 % confidence interval: ± 17.50 %). Open-surface water bodies display discernible spatiotemporal differences. Stable and continuous permanent water bodies are predominantly in mountainous areas, whereas seasonal water bodies with pronounced fluctuations are chiefly found in desert-oasis areas. Climate change is the dominant factor that affects the changes of water bodies on the surface of mountain regions, while human social activities also have a significant impact on desert-oasis areas. The improved methodology adopted in this study offers a robust and scalable framework that can be tailored for studying changes in open-surface water bodies in intricate environments. We performed a comprehensive analysis of the changes and drivers of open-surface water bodies on the north side of the Kunlun Mountains over time and space. This work is aimed at providing data support for scientifically appraising the development potential of water resources in Southern Xinjiang and addressing the disparity between water resource supply and demand.

Late Pleistocene small mammals (Chiroptera, Rodentia, Lagomorpha) from Agios Georgios Cave (Kilkis, Central Macedonia, Greece)

The Late Pleistocene small mammal fauna from Agios Georgios Cave (Kilkis, Central Macedonia, Greece) is examined, resulting in the identification of 14 species of Chiroptera, Rodentia and Lagomorpha. The palaeoenvironment of the area around the cave seems to have been a relatively arid, steppe-like plain with sparsely-wooded patches. There was also a permanent or temporary water body near the cave. The palaeoclimate of the region was colder than today, but rather warm compared to more northern parts of Europe, which were strongly affected by the Last Glacial Maximum.

Urban water bodies in China: Spatial distribution patterns, temporal change characteristics, and relationship with economic development

Urban water bodies constitute a vital element within the urban ecosystem. Knowledge of the spatiotemporal changes in urban water bodies and their relationship with economic development in China is critical for sustainable development. However, previous studies usually investigated the spatiotemporal changes of urban water bodies at discrete time points and ignored the relationship between urban water bodies and economic development. Here, this study first corrected freely available water body products based on spatiotemporal majority filter, thereby obtaining an improved yearly urban water body dataset. Then, the research adopted Moran’s I and Anselin Local Moran’s I to explore the spatial distribution patterns of urban water bodies and employed linear regression and segmented linear regression to investigate the temporal abrupt change and long-term trend of urban water bodies. Finally, we used geodetector to evaluate the relative contributions of GDP to the spatial heterogeneity of trends in urban water bodies. The study revealed a significant spatial autocorrelation in the distribution of urban water bodies, particularly notable in the “High-High” cluster within the Yangtze and Pearl River Deltas. It was observed that approximately 40 % and 60 % of total cities experienced an abrupt change in permanent and seasonal urban water bodies, respectively. Specifically, the majority of these abrupt changes occurred during 2010–2013. When considering both long-term trends and abrupt changes, permanent urban water bodies in Chinese cities exhibited primarily a steadily increasing trend, while seasonal water bodies in Chinese cities displayed two distinct temporal patterns: a steadily increasing trend and a decreasing trend followed by a subsequent increasing trend. Furthermore, it was noted that GDP exhibited a significantly positive correlation with the temporal changes of permanent urban water bodies from 2000 to 2020 at the national scale while it first showed a significantly negative correlation with the temporal changes of seasonal urban water bodies from 2000 to 2012 and then showed a significantly positive correlation from 2012 to 2020 on a national scale. In conclusion, we found that GDP played a more important role in driving the spatial heterogeneity of trends in urban water bodies during 2012–2020 compared to 2000–2012, with the relative contribution of ∼ 32.5 %.

Water distribution based on SAR and optical data to improve hazard mapping

Climate projections foresee intense precipitation and long-term drought events is increasing with consequent rapid changes in surface water bodies in a short period. In areas with drastic hydrological changes, achieving accurate and rapid mapping of these phenomena in combination with hydrologic variability characteristics is a key of effective emergency management and disaster risk reduction plans. This study presents an automatic method for mapping drought and flood hazards, particularly in regions with significant hydrological changes. We use Sentinel-1/2 and Landsat data to extract surface water and classify permanent and seasonal water bodies in historical periods, which serve as the basis for identifying flood or drought areas. The water extraction method combines index-based analysis for optical data and the region-Otsu method for radar data, ensuring accurate identification of water. The effectiveness of this approach is demonstrated through comparisons with existing products in Poyang Lake (China), the Po River Plain (Italy), and the Indus River Plain (Pakistan). Findings show a high similarity between the two, and our results can provide more specific details. Our method is particularly well-suited for areas with fluctuating hydrological conditions, can also map quickly without optical data. By effectively identifying areas affected by drought and flood hazards while mitigating errors from natural hydrological dynamics, this methodology contributes valuable insights to enhance emergency management and disaster risk reduction plans.

Eemian paleoenvironment based on the freshwater malacofauna and isotope record (Piła site; north-western Poland)

This article presents the results of malacological and isotope studies on lacustrine sediments from the Eemian interglacial site in the Piła (north-western Poland). Twenty species of molluscs were found in the analysed sediments. Changes in the taxonomic composition and the quantitative structure of malacofauna in the profile allowed distinguishing five types of assemblages corresponding to different phases of the lake's evolution. Ratios of oxygen and carbon isotopes (δ18O and δ13C) reflecting changes in the lake water composition were measured in shells of two predominating snail species, Valvata piscinalis (Müller, 1774) and Bithynia tentaculata (Linnaeus, 1758), and in opercula of Bithynia tentaculata. Significant variability in isotope contents was noted for shells in individual profile sections and between analysed taxa. The results of malacological and isotope studies were supplemented with lithological, stratigraphical and palynological data. On this basis, the sediments age was determined (optimal and suboptimal phases of the Eemian interglacial). Environmental changes of paleolake have been also reconstructed. The analysed sediments were initially deposited in the coastal, periodically drained zone of the reservoir. The younger part of the sequence represents the shallow part of the littoral zone of the permanent water body. The malacological and isotope data also allowed distinguishing two phases of increased water level in the reservoir, and changes in its trophic state probably generated by climatic factors.

Phyllodiaptomusparachristineae, a new species of copepod (Copepoda, Calanoida, Diaptomidae) from the floodplain of the lower Mekong River Basin in Thailand and Cambodia.

Phyllodiaptomus (Phyllodiaptomus) parachristineaesp. nov., a new diaptomid copepod, was collected from 30 sites in the lower Mekong River Basin floodplain in northeastern Thailand and nine sites in Cambodia. The new species is the 13th species of the genus to have been recorded across Asia. It has a wide range of habitats, occurring in small to large, temporary to permanent water bodies, and it can be found at any time of the year. The morphology of the new species is most similar to that of the males of P. (P.) christineae, having a comb on the antepenultimate segment on the right antennule, symmetrical caudal rami, a narrow hyaline lamella on the left P5 basis, a distal accessory spine on the right P5Exp-2, and a single-lobed Enp on the right P5. On the other hand, the males of the new species have second and third urosomites without hair-like setae on the ventral margin, a rounded distal margin of the P5 intersclerite plate, a semi-circular lamella on the right P5 basis, a strong principal lateral spine inserted at the proximal 1/3 of the right P5Exp-2, and a two-segmented left P5Enp. Morphological differences among species in the subgenus Phyllodiaptomus (Phyllodiaptomus) as well as the distribution and habitats of the 13 species and two subspecies of Phyllodiaptomus in Asia are discussed.