Major Lakes Research Articles

Establishing the Hydrological Controls on Water Surface Area Variations in Oxbow Lakes

ABSTRACTOxbow lakes are iconic fluvial landforms found in the floodplains of meandering rivers around the world. Their formation is associated with meander cutoff, a process that excises sections of river channel to optimise the downstream transmission of water and sediment. Overbank floods and conveyance through tie channels maintain some hydrological connectivity, but lakes are generally considered to passively infill until they are terrestrialised. Here, a suite of 64 lakes across two meandering rivers in the Bolivian Amazon Basin are used to demonstrate the hydrological dynamism of oxbow lakes by quantifying interannual variations in lake water surface area (WSA), using the modified Normalised Difference Water Index (mNDWI) on an archive of Landsat images, and evaluating the mechanisms controlling these changes using remotely sensed rainfall data and geospatial analysis. The majority of lakes (75%) decreased in size over the study period, while 25% increased in size. The results suggest that WSA variations are controlled by proximity to the active channel, with the magnitude of these variations being set by mechanisms of connectivity. Lakes connected by tie channels experienced WSA changes up to 3.9 times larger than lakes with no visible connection mechanisms. Incursion lakes displayed similar WSA changes to those with tie channels, while isolated lakes were found furthest from the mainstem and had the smallest range of WSAs. Chute lakes experienced a wider range of WSA change (−95% to +281%) and were more strongly controlled by mainstem proximity than neck lakes. Connectivity between the river and oxbow lakes is essential for governing lake hydrodynamics, and tie channels provide the critical conduit by which water can be transmitted deep into the floodplain.

Biogeographical influences on the nutritional and sensory attributes of Pearlspot Cichlid (Etroplus suratensis)

The pearlspot cichlid (Etroplus suratensis) occurs naturally in the water bodies of peninsular India and Sri Lanka. Six stations across three major lakes in Peninsular India are used to analyze the effects of biogeographical distribution on the nutrient profile, meat quality, and organoleptic qualities of pearlspot. The analysis included parameters such as gut content, proximate composition, fatty acid and amino acid profiles, meat colour, texture, and organoleptic acceptability, along with water parameters. The nutrient profile and sensory attributes of pearlspot are significantly influenced by biogeographical factors. The fish from higher saline areas Azhikode and Kanjiracode with 18.23 and 15.13 ppt, had better sensory acceptance. These sites had a higher proportion of diatoms (75.91%) and zooplankton (3.19%), respectively. The fish from Azhikode also had higher levels of protein (18.31%). The ratio of essential to non-essential amino acids was found to be optimal in all the stations. Azhikode samples had the highest concentration of polyunsaturated fatty acid (PUFA) (16.42%) and n3/n6 ratio (1.81). The meat color and texture of the fish samples significantly differed among the stations. The study demonstrates the importance of biogeographical factors on flavor, texture, and nutritional profile. The findings indicate that the production of nutritionally and organoleptically superior fish is possible by ensuring a proper rearing environment and diet.

Socio-hydrological lock-in; an emergent phenomenon in the face of anthropogenic drought

This study investigates the drought of three major terminal lakes: Great Salt Lake, Salton Sea, and Lake Urmia, driven by socio-hydrological lock-in—a phenomenon characterized by feedback loops between human activities and environmental processes. Previous research has linked this drying to socio-hydrological lock-in, where rational actions by individuals collectively lead to suboptimal outcomes, exacerbating water scarcity and ecological degradation. Despite existing studies, a critical knowledge gap remains in understanding how these feedback mechanisms operate across different socio-economic and ecological contexts. This research seeks to address this gap through an integrative analysis of historical data and case studies, highlighting the interplay between increased water demand for agriculture, population growth, and governance challenges. The resultant shrinkage of these lakes exposes saline playas, generating salt-rich dust with severe ecological and health impacts, including soil salinization and respiratory illnesses. By comparing the socio-hydrological lock-in across diverse regions, this study provides insights into preventing and mitigating these cycles. It emphasizes the necessity for holistic water management strategies that integrate both supply and demand-side measures. The key contribution of this research lies in its systematic exploration of the feedback mechanisms driving socio-hydrological lock-ins, offering a foundation for developing sustainable water resource management policies globally. This work aims to influence policy and practice by highlighting the need for integrated, long-term strategies that balance economic pursuits with environmental sustainability, ensuring resilience in water management amidst mounting environmental challenges.

Comprehensive evaluation of water quality grades based on improved CRITIC and multidimensional connection cloud combination

AbstractThis study proposes a comprehensive water quality assessment method for nine major plateau lakes in Yunnan Province, based on an improved CRITIC method combined with a multidimensional connectivity cloud model. Key water quality monitoring indicators (NH3‐N, COD, TP, TN, permanganate index, DO, pH) were selected, and the weights were determined using the improved CRITIC method, highlighting the impact of NH3‐N, COD, and TP. These weights were then integrated with a multidimensional connectivity cloud model to classify lake water quality levels. The results indicated the following water quality grades for the lakes: Dianchi (III), Fuxian Lake (I), Erhai (II), Xingyun Lake (I), Qilu Lake (II), Yilong Lake (II), Lugu Lake (I), Yangzonghai (II), and Chenghai (II). Compared to five conventional methods, the proposed approach better addresses the issues of fuzziness, randomness, and discreteness in water quality indicators, avoiding the boundary selection problems inherent in traditional methods. By combining the improved CRITIC method with a multidimensional connectivity cloud model, the study achieves more precise and reliable evaluations through objective weighting and comprehensive consideration of multiple indicators. This method offers a more accurate reflection of lake water quality conditions and provides a scientific basis for water quality management and decision‐making, demonstrating significant potential for application in the field of environmental science.

Dust over water: Analyzing the impact of lake desiccation on dust storms on the Iranian Plateau

The desiccation of lakes on the Iranian Plateau, driven by both natural processes and anthropogenic activities, has led to significant land cover changes, exposing lake beds and triggering adverse environmental consequences. These transformations pose serious threats to ecological conditions and the provision of ecosystem services. This study investigates the potential links between lake desiccation and the occurrence of dust storms across major lakes on the Iranian Plateau. By utilizing remote sensing data and time series statistical analysis, including the Mann-Kendall test, Ordinary Least Square (OLS) regression, and frequency analysis, we assessed changes in lake extent and their effects on Aerosol Optical Depth (AOD) and Particular Matter (PM2.5) from 1985 to 2020. An analysis of Landsat imagery reveals that lake desiccation commenced in the late 1990s, exhibiting a marked downward trend that has intensified in recent years. The results show a significant inverse correlation between aerosol parameters (AOD and PM2.5) and lake extent. Reduced lake area is associated with elevated AOD and PM2.5 concentrations, with the highest aerosol levels observed when lakes reach their smallest extent. Notably, despite an 81 % reduction in the lake area, dust storm occurrences have increased by 20%. These findings highlight the critical role of lake desiccation in exacerbating dust storms in the surrounding regions. Furthermore, the temporal alignment between fluctuations in lake extent and dust storm frequency is validated through regression analysis with a 95 % confidence level. The consistency between our results and existing literature underscores the reliability of the observed relationship, emphasizing the urgent need to address the environmental consequences of lake desiccation to mitigate its broader ecological impacts and potential human health impacts.Graphical Abstract

Large inversions in Lake Malawi cichlids are associated with habitat preference, lineage, and sex determination.

Chromosomal inversions are an important class of genetic variation that link multiple alleles together into a single inherited block that can have important effects on fitness. To study the role of large inversions in the massive evolutionary radiation of Lake Malawi cichlids, we used long-read technologies to identify four single and two tandem inversions that span half of each respective chromosome, and which together encompass over 10% of the genome. Each inversion is fixed in one of the two states within the seven major ecogroups, suggesting they played a role in the separation of the major lake lineages into specific lake habitats. One exception is within the benthic sub-radiation, where both inverted and non-inverted alleles continue to segregate within the group. The evolutionary histories of three of the six inversions suggest they transferred from the pelagic Diplotaxodon group into benthic ancestors at the time the benthic sub-radiation was seeded. The remaining three inversions are found in a subset of benthic species living in deep waters. We show that some of these inversions are used as XY sex-determination systems but are also likely limited to a subset of total lake species. Our work suggests that inversions have been under both sexual and natural selection in Lake Malawi cichlids and that they will be important to understanding how this adaptive radiation evolved.

Anthracological data as evidence of cultural distinctions in wood usage by communities from the Western Baltic cultural circle in Poland

More than 15,000 records were collected and analysed for all taxonomic determinations of tree and shrub remnants published to date, associated with the activities of the Western Balts, who inhabited the Masurian Lake District and the Lithuanian Lake District (NE Poland) during the Roman Iron Age (1st to late 4th century CE), the Migration Period (late 4th to mid/late 6th century CE) and the Early Middle Ages (10th to late 12th/early 13th century CE). The analysis included anthracological data from 20 archaeological sites, representing the settlements of the Bogaczewo culture, the Sudovian culture, the Olsztyn group and the early medieval Yotvingia.The aim of the study was to capture and characterise the differences in the use of wood by neighbouring cultures within the Western Baltic cultural circle, who had a similar raw material base, both regionally and chronologically.The analysis revealed significant differences in the use of available wood types between the Bogaczewo culture and the Sudovian culture. The former relied on deciduous trees, primarily birch, oak and alder, both in everyday life and during funerary rituals. In contrast, the Sudovian culture predominantly utilised softwoods such as pine, spruce and yew. For funeral pyres, these communities exhibited a marked preference for a specific type of wood: birch for the Bogaczewo culture and pine for the Sudovian culture. This preference was likely related to the symbolic significance of these trees in the mythology and folklore of the Baltic peoples, as well as their distinctive appearances and growth habits. The absence of oak wood for cremation, despite its central importance in the religious practices of the ancient Prussians, may have been due to prohibitions rooted in spiritual sphere.

Surface water dynamics of Africa: Analysing continental trends and identifying drivers for major lakes and reservoirs

ABSTRACT Africa has the most dynamic demographic development worldwide. Current projections predict a population of > 3 billion people by the end of the century. Sub-Saharan Africa alone will likely see a 40% increase in population between 2020 and 2050. Although it is well known that large parts of Africa are in a constant state of water stress, its surface water resources remain understudied. This study analyses long-term trends of surface water in Africa. It identifies causal impacts on major lakes and reservoirs for the timeframe 2003–2020, as well as dynamic and causal similarities between the various lakes. For this, a set of daily time series based on Earth observation is employed. Global WaterPack data is used for a daily uninterrupted time series of the continent’s surface water area. Additionally, an array of relevant independent variables, namely precipitation, total evapotranspiration, groundwater, soil moisture, and gross primary productivity (GPP) in different land use areas is analysed. For causal identification, the Peter and Clark Momentary Conditional Independence algorithm is used. Findings show that > 42% of African countries and > 34% of African ecoregions experience shrinking surface water area. Over 80% of investigated surface water bodies are driven by the surface water in their upstream subbasins and GPP in agriculturally used areas. About 85% of investigated lakes are significantly driven by agricultural usage, often in the form of water abstraction, as referenced regional studies confirm. Our analysis demonstrates the feasibility of conducting causal analyses of surface water dynamics using Earth observation data. Dynamically similar lakes are often impacted by the same drivers, forming regional lake clusters. Considering the causes identified may greatly help adapt strategies for sustainable development. A causality analysis to identify drivers of surface water dynamics has, to our knowledge, never been performed before on this scale and at such high temporal resolution.

ASSESSMENT OF PHYSICO-CHEMICAL PARAMETERS OF PERUMAL ERI

Tamilnadu is deficit in Water Resources. It is a major fresh water lake in the cuddalore district of tamilnadu. It is located almost 7 kilometers (4.3 mi) from Alapakkam,The rainfall is seasonal and often erratic in timing and geographical distribution, resulting in frequent droughts and occasional floods. To mitigate the adverse effects, serious attention is required to rehabilitate the existing irrigation structures, canal systems, anicuts and tanks to make them functionally more effective, conserve and utilize the water for optimum use.This paper deals with an assessment of water quality parameters of Perumal eri(lake) situated at Alapakkam in Cuddalore district.Samples have collected at five different locations in Perumal eri during pre-monsoon period.Then laboratory analysis has done and the results are compared with BIS and WHO drinking water standards.Then by using “Inverse Distance Weighting”(IDW) method geostatistical analysis has done.Based on the results obtained mapping contaminants in lake has done by using ArcGIS software.According to the results suitable solution will be given to treat the water in the lake.

Anthropogenic vs. climatic drivers: Dissecting Lake desiccation on the Iranian plateau

Lakes are indispensable to ecological balance, supporting biodiversity and human welfare. Despite their importance, lakes around the globe are diminishing at an alarming rate, presenting substantial environmental challenges exacerbated by climate variability and human-induced pressures, such as unsustainable land management and excessive water withdrawals. This study offers an extensive analysis of the desiccation phenomena affecting major lakes on the Iranian plateau, dissecting the complex interplay of contributing factors. We examine meteorological, hydrological, and agricultural drought conditions using indices like SPI, SDI, and SPEI to gain nuanced insights into drought dynamics. This study sheds light on the factors that contribute to the drying up of lakes and quantifies the impact of anthropogenic and climatic drivers on this phenomenon. The findings indicate that the area of all lakes has declined dramatically after the change point, ranging from 51% in the Urmia Lake to an impressive rate (i.e. 100%) in Southern Hamun. Despite the stable rate of meteorological droughts (increasing in temperature by about 1 °C since the 90s and stable precipitation patterns across most basins), the research highlights the ongoing struggle against severe hydrological and agricultural drought conditions. The study delineates the predominant role of anthropogenic activities in the diminishing lake inflows and the consequential drying of the lake, accounting for approximately 100 % in five of the seven lakes.

Diatom species responses along gradients of dissolved inorganic carbon, total phosphorus, and lake depth from lakes across Canada.

Diatoms are key components of freshwater ecosystems and are regularly used for paleolimnological reconstructions, in which defining species optima and tolerances is fundamental for interpreting assemblage shifts in a sediment record. Here, we examinedresponses of diatomsacross three major environmental gradients-dissolved inorganic carbon (range: 0.1-230.5 mg · L-1), total phosphorus (range: 3-326 μg · L-1), and maximum lake depth (range: 0.9-55.0 m)-taken from 158 lakes from across Canada. The lakes were sampled as part of the LakePulse Network, which conducted a standardized sampling of lakes spanning 12 Canadian ecozones. Hierarchical logistic regression was used to model the species responses of 37 common taxa, and species optima and tolerances were calculated with weighted average modeling. The most common response detected was the symmetrical unimodal model, suggesting we likely captured the full environmental ranges for many species, although skewed unimodal responses were also common. Indicator species analyses identified taxa with high predictive values and fidelities to particular ecozones, with high-nutrient-adapted taxa such as Stephanodiscus spp. and Cyclotella meneghiniana characteristic of the agriculturally productive Prairie region. The Prairies stood out in the dataset as the region with the most unique flora from the local contribution to beta diversity analysis. Overall, the autecological data provided by our study will allow for improved interpretations of paleolimnological records and other biomonitoring efforts, addressing management concerns and contributing to a better understanding ofour changing environment.

Impact of Rapid Urbanization and Encroachment on the Major Lakes of Chennai: A Spatial Analysis

Impact of Rapid Urbanization and Encroachment on the Major Lakes of Chennai: A Spatial Analysis

Unlocking Nile tilapia (Oreochromis niloticus Linn., 1758) selective breeding programmes in Uganda through geographical genetic structure mapping

AbstractNile tilapia (Oreochromis niloticus), native to Africa and the Levant, is an important species for both aquaculture and capture fisheries. Despite these attributes, Nile tilapia has been negatively impacted by anthropogenic activities ranging from overfishing and habitat destruction to translocations. These human‐mediated activities have threatened the genetic evolutionary integrity of native populations of Nile tilapia and congeneric species through admixture, demographic bottlenecks and introgressive hybridization. In this context, the genetic contrast between farmed/bred strains and wild Nile tilapia populations in the major lakes of Uganda remains understudied. Understanding the genetic structure of Nile tilapia populations in the major water bodies of Uganda (lakes Victoria, Kyoga, Edward, George, Albert and Nile River) is a key resource to guide selective breeding programmes, thus minimizing the effects of maladaptation under both aquaculture and natural stocks. Although the population genetics of Nile tilapia in Uganda's major lakes have been studied, this was based on limited sampling scope, especially in the wild, and the key information on the species could have been overlooked. We fill this knowledge gap by genotyping 756 Nile tilapia individuals from multiple populations for each major water body of Uganda using a panel of 34 microsatellite loci based on the microsatellite genotyping‐by‐sequencing (SSR‐GBS) technique. The results indicate two discrete gene pools/stocks: the Edward‐George system and the Albert‐Kyoga system‐Victoria. Evidence of loss of genetic diversity and admixture of some Nile tilapia stocks was found, most likely resulting from anthropogenic perturbations. This study contributes useful information key for understanding the potential Nile tilapia broodstock sources for selective breeding programmes, aimed at improving aquaculture production in Uganda.

Surface water area dynamics of the major lakes of Ethiopia (1985–2023): A spatio-temporal analysis

Ethiopian lakes face multiple ecosystem threats from human and natural factors, including climate change. The long-term dynamics of water surface area in many lakes remain unknown. This study presents the first comprehensive account of major Ethiopian lakes’ long-term water surface area dynamics, providing essential information for prioritizing hydrological conservation strategies. We extracted the time-series water surface area of the lakes from Landsat images in the Google Earth Engine (GEE), using the Modified Normalized Water Index (MNDWI) and machine learning (Random Forest) methods. Random Forest (RF) outperformed MNDWI across many lakes, especially when water body spectral characteristics became complex. A comparison of the results with the Joint Research Center (JRC) Global Surface Water Mapping Layers showed a good agreement. Long-term water surface area dynamics showed both common and distinct trends. Common trends included: (a) similar recession and expansion periodicities despite lakes being in different climatic zones, (b) an increase in the inter-annual variability of water area after 2000, and (c) a common abrupt point in time (2000/2001). Distinct trends included: (i) long-term decline in five lakes (Abiyata, Langano, Shalla, Chamo, and Hayq), (ii) expansion in three lakes (Ziway, Hawassa, and Abaya), and (iii) non-homogeneous long-term trends in two lakes (Tana and Hardibo). These common and distinct trends show the interplay of climate phenomena and lake-specific factors. Climate factors govern inter-annual lake area change (decreasing/increasing) and recession and expansion cycle periods. The magnitudes of changes and recovery rates after each change cycle vary based on lake-specific factors. We recommend prioritizing conservation efforts for lakes with high water storage degradation risks, as indicated by significant water loss over the historical period and persistent long-term declining trends. This includes Abiyata, Chamo, Shalla, Langano, Hayq, and Hardibo, in order of priority.

Biogeography of freshwater plants in four major lakes in Kenya

Freshwater plants play a pivotal role in the health and functioning of freshwater ecosystems, and they also offer a variety of benefits to humans. Despite their importance, there is a significant gap in our understanding of the macroecology of freshwater plants in tropical regions, where biodiversity is typically high, and ecosystems face substantial pressures from human activities. To bridge this knowledge gap, we conducted extensive field surveys and applied statistical methods to understand the patterns of distribution, density, and diversity of freshwater plants and their relationship with abiotic components in four freshwater lakes in Kenya. We aimed to answer four key questions: (1) How many freshwater plant species occur in these lakes? (2) What proportion of these freshwater plant species are native and alien to Kenya? (3) What proportion of these species have a history of being invasive somewhere in the world, including in Kenya? (4) Which water and sediment characteristics are significantly associated with the presence, density, and diversity of freshwater plants in the lakes? We inventoried a total of 163 freshwater plant species, of which 114 were native to Kenya and 49 were alien. Online database searches revealed that 114 species had a history of invasion globally, with 22 species already invasive in Kenya. Our statistical analysis showed that the presence and density of plant species were positively correlated with pH and turbidity, but negatively correlated with soluble reactive phosphorus in both water and sediments, ammonia-nitrogen in sediments, and nitrate-nitrogen in water. Shannon-Wiener diversity of the plant species was positively correlated with ammonia-nitrogen in water and nitrate-nitrogen in sediments but negatively correlated with longitude and electrical conductivity of the water. Pielou’s evenness within the communities showed positive correlations with soluble reactive phosphorus in both water and sediments, ammonia-nitrogen in sediments, and nitrate-nitrogen in water but was negatively correlated with water turbidity and pH. The number of species with a history of invasion was positively correlated with longitude and electrical conductivity but negatively correlated with ammonia-nitrogen and nitrate-nitrogen in water. This extensive inventory not only enriches our understanding of the biodiversity within these freshwater plant communities but also highlights the potential risks posed by species with a history of being invasive. The findings regarding environmental variables linked to the presence, density, diversity, and invasive potential of these species underscore the complexity of freshwater ecosystems and the array of factors influencing the composition of freshwater plant communities.

Response of changes in lake area to drought and land use change

The lake area is a crucial parameter that characterizes the state of a lake. Under the dual pressures of climate change and human activity, the magnitude and frequency of changes in lake areas become more pronounced. This process poses a serious threat to the local ecological environment. In this study, we constructed a lake water extraction model (LakeNet) based on a fully convolutional neural network. We extracted and analyzed the spatiotemporal characteristics of the area of nine major lakes from 1987 to 2022, as well as the driving factors behind these changes. Our results indicate that: 1) LakeNet exhibits high extraction accuracy and can remove some clouds. 2) The area of the nine major lakes shows a fluctuating downward trend (−8.11km2/10a), with drought and land use changes identified as significant driving forces behind the changes in lake boundaries, drought events caused the lake area to decrease, and the expansion of cropland further reduced the lake area. 3) Due to variations in lake area, the impact of drought on the area of the nine major lakes exhibits a lag effect, smaller lakes are likely to respond more quickly to drought.

Floating on groundwater: Insight of multi-source remote sensing for Qaidam basin

Situated in the north of the Qinghai-Tibet Plateau, the Qaidam Basin experiences limited precipitation and significant evaporation. Despite these conditions, it stands out as one of the most densely distributed lakes in China. The formation of these lakes is controversial: whether the lake water primarily originates from local precipitation or external water sources. To address this issue, this paper explores the recharge sources of lakes in the Qaidam Basin and the circulation patterns of groundwater from a remote sensing perspective. Based on deep learning networks, we optimized the soft object regions of the Object-Contextual Representations Network (OCRNet) and proposed the Remote·Sensing Adaptive-Improved OCRNet (RSA-IOCRNet). Compared with seven other networks, RSA-IOCRNet obtained better experimental results and was used to construct an area sequence of 16 major lakes in the Qaidam Basin. Combined with multi-source data, the comprehensive analysis indicates no significant correlation between climatic factors and lake changes, while an obvious correlation between lakes and groundwater changes in the eastern Qaidam, consisting with the results of the field survey. Deep-circulating groundwater recharges numerous Qaidam lakes through upwelling from fault zones, such as Gasikule Lake and Xiaochaidan Lake. Groundwater in the Qaidam Basin is more depleted in hydrogen-oxygen isotope characteristics than surface water in the basin, but similar to some river water in the endorheic Tibetan Plateau. This indicates that Tibetan seepage water, estimated at approximately 540 billion m3/a, is transported through the Qaidam Basin via deep circulation. Moreover, it rises to recharge the groundwater and lakes within this basin through fracture zones, extending to various arid and semi-arid regions such as Taitema Lake. This work provides a new perspective on the impact of deep groundwater on lakes and water circulation in these areas.

Fibulae in the Form of Overlays in the Archeology of the Western Balts of the Merovingian Age

The article is devoted to a unique phenomenon in the archeology of the Baltics – Aestii and Prussian brooches imitating belt linings and details of a horse headband. They date from the early 5th – early 8th century AD. According to its shape, these brooches are divided into two variants. Fibulae var. 1 of the early phase of the era of the Great Migration of Peoples are associated with the Aestii of Sambia on the threshold of the emergence of the Prussian archaeological culture, and the clasps of var. 2 came out of the workshops of the western part of the Masurian Lake District in the final phase of the mentioned era. The sizes and shapes of the studied brooches directly point to their prototypes: linings of various accessories. By searching for such analogies, the origin and dating of brooches-overlays obtained as a result of excavations of burial grounds on the western outskirts of the Baltic world is clarified. The brooches of both of the aforementioned variants, belonging to the bearers of the cultures of various Western Baltic tribes, were made over the course of three centuries (with interruptions). Fasteners var. 1 were included in male and female burial complexes. Fasteners var. 2 belonged exclusively to male complexes. The social affiliation of the owners of brooches var. 2 can be defined as members (or relatives) of a squad group. It was professional warriors who had luxurious horse headbands with fours, imitating the Frankish models of the Merovingian era. A similar phenomenon was noted on the example of women’s pendants with retinue symbols in Eastern European antiquities of the Viking Age, which was not previously noted in Russian archeology.

INWESTYCJE NA SZLAKU WIELKICH JEZIOR MAZURSKICH. AKTYWNIE PO RELAKS – JACHTEM CZY ROWEREM?

The Great Masurian Lakes Trail, valued for its picturesque landscapes and rich natural environment, was recognized as an ideal place for enthusiasts of active leisure. Thanks to modernizations in sailing and cycling tourism, users are offered a variety of relaxation opportunities and comfort during cruises on the lakes, as well as while exploring the region by bikes. The renovation of the water trail and the creation of a new bicycle path have enabled nature-friendly exploration of Masurian attractions. Special attention was given to ecomarinas, which are investments promoting an ecological approach to sailing and minimizing the negative impact of tourism on the environment. The need to integrate active forms of recreation with modern amenities was identified to develop the Masuria as an attractive tourist destination, while balancing between the local economy and the protection of heritage. These investments will contribute to the promotion of a healthy lifestyle, the preservation of biodiversity, and the sustainable development of tourism.

A Qualitative Study of Water Quality Using Landsat 8 and Station Water Quality-Monitoring Data to Support SDG 6.3.2 Evaluations: A Case Study of Deqing, China

Facing the challenge of the degradation of global water quality, it is urgent to realize the Sustainable Development Goal 6.3.2 (SDG 6.3.2), which focuses on improving global water quality. Currently, remote sensing technology is widely used for water quality monitoring. Existing water quality-monitoring studies have been conducted based on quantitative water quality inversion. It requires a high degree of the synchronization of the time and location of the collection of station monitoring data and remote sensing data (air–ground spatiotemporal synchronization), which can be resource intensive and time consuming. However, policymakers and the public are more interested in the quality of water (good or poor) than in the specific values of the water quality parameters, as evidenced by the emergence of SDG 6.3.2. In this study, we change the traditional idea of quantitative water quality research, focus on water quality qualitative research combined with the characteristics of water pollution, propose a remote sensing water quality sample enhancement method under the condition of “air–ground spatiotemporal asynchrony”, and construct a remote sensing water quality sample library. On the basis of this sample library, a random forest water quality classification model was constructed to classify water quality qualitatively. We obtained the distribution of good water bodies in Deqing County, China, for example, from 2013 to 2022. The results show that the model has high accuracy (Kappa = 0.6004, OA = 0.8387), and we found that the water quality in Deqing County improved in the order of “major rivers, lakes, and tributaries” during the period from 2013 to 2015. This also verifies the feasibility of using this sample enhancement method to conduct qualitative research on water quality. Based on this water quality classification model, a set of spatial-type evaluation processes of SDG 6.3.2 based on image elements was designed. The evaluation results show that the water quality situation in Deqing County can be divided into two stages: there is a trend of substantial improvement from 2013 (evaluated value of SDG 6.3.2 = 63.25) to 2015 (evaluated value of SDG 6.3.2 = 83.16); and it has remained stable and fluctuating after reaching the good environmental water quality since 2015. This study proposes a simple method for rapidly evaluating SDG 6.3.2 via utilizing easily accessible Landsat 8 and water quality-monitoring data to classify water quality. The method can directly obtain water quality category information without the need for additional sampling, thus saving costs. It is a very simple process that is easy to implement, while also providing a high level of accuracy. This significantly reduces the barriers to evaluating SDG 6.3.2, supports the realization of the sustainable management of water resources globally, and is highly generalizable.