Open Water Bodies Research Articles

Integrated water quality assessment of open water bodies using empirical equations and remote sensing techniques in Bangweulu Wetland lakes, Zambia

Water quality assessment is essential for conserving aquatic ecosystems and human consumption. However, monitoring several water quality parameters in open water bodies poses significant challenges, resulting in gaps and limitations. While the Water Quality Index (WQI) integrates various water quality parameters, its spatial application has not yet been thoroughly evaluated. To address these issues, this study was conducted to establish an integrated remote sensing approach for comprehensive monitoring of water quality. Utilising Sentinel 2 data alongside on-site/lab water quality measurements, various relationships were established. The calculated mean WQI from on-site/lab data was 35, while from remotely sensed data was 41. Linear relationships (R2) between WQI and various water quality parameters such as chloride (0.712), sodium (0.705), TDS (0.705), turbidity (0.628), and EC (0.704) were observed. These relationships facilitated the transformation of water quality parameter maps into WQI maps, the WQI maps were then integrated into one WQI map showing the overall water quality status of the Bangweulu Wetland lakes. Both on-site/lab and remote sensing methods indicated that the concentrations of water quality parameters in the Bangweulu Wetland lakes is lower (better) than the local and international recommended limits, with a calculated WQI falling within the ’Good’ category. This indicates that the water is fresh, clean, and suitable for various purposes including ecological preservation, agriculture, aquaculture, recreation, industrial use, and human consumption. The findings offer insights into the general status of water quality in open water bodies, identifying hot spots and potential sources of water pollution with implications for future management practices.

THE VERTEBRATE FAUNA OF THE LOWER PLIOCENE CONTINENTAL DEPOSITS IN THE EBRO DELTA (BAIX EBRE BASIN, NE SPAIN)

The Pliocene faunas of the northeastern Iberian Peninsula are poorly known due to the scarcity of deposits from this interval. In this context, the site of Sant Nofre-Campredó (Baix Ebre, Catalonia, Spain), comprising two contemporaneous outcrops belonging to geologically correlated sections (Sant Nofre and Campredó-Via Fèrria), makes a significant contribution to the study of Pliocene faunas in this region. The first vertebrate remains were recovered in the late 1970s in clay deposits close to the Sant Nofre Hill. Later, intensive sampling in the 1980s at the Campredó-Via Fèrria outcrop led to the recovery of more than a hundred fossil specimens, including small vertebrates and large mammals. Here, we revise these collections to expand and update the vertebrate list, better constrain the age of the continental deposits, and characterize the environment and climate around the mouth of the Ebro River during the formation of the site. Up to 24 vertebrate species have been identified at Sant Nofre-Campredó, including amphibians, reptiles, and mammals. The presence of the rodents Paraethomys baeticus Piñero & Verzi, 2020, Apocricetus barrierei (Mein & Michaux 1970), and Occitanomys brailloni Michaux, 1969 implies an early Ruscinian age (MN14 unit) for the two outcrops. Biostratigraphic correlations with other well-dated sites in the Iberian Peninsula refine the estimated age of Sant Nofre-Campredó to approximately 4.6 Ma. The ecological affinities of the identified fauna reveal a landscape dominated by woodland habitats in the surroundings of the site during the Early Pliocene, with presence of open humid meadows and water bodies under warm and moist climatic conditions.

Surface water dynamics of Lake Chad Basin (Sahelian Africa) based on daily temporal resolution Earth observation time series

ABSTRACT Water availability is vital for the sustenance of livelihoods in the Lake Chad Basin. However, the daily and seasonal dynamics of open water bodies are not well understood. This study aims to (1) analyze the daily and seasonal dynamics of water bodies, (2) estimate changes in surface water area extent including trends and change points, and (3) assess the connection between surface water extent and seasonal rainfall variation. To achieve this, we used the Global WaterPack and ERA5-Land daily aggregated datasets. We employed time series decomposition, trends analysis, and temporal lag correlation in our analysis. The results showed strong seasonal patterns of natural lakes compared to reservoirs/dams. Between 2003 and 2022, Lake Chad averaged 2,475.64 km2. The Northern pool of Lake Chad exhibited significant fluctuations, remaining below 600 km² between 2005 and 2012, from 2016 to 2019), with less than 350 km2 lasting only for a few days annually. The Southern pool averaged between 2,200 and 2,400 km2, except during drought years (2006–2007), specifically between the days of the year to approximately 66, and days 301–365/6. In Lake Fitri, the yearly maximum and minimum water extents were observed between days 1–59 and 305–365/6, and between days 60 and 304, respectively.

PROPER NAMES OF THE SEAS: STRUCTURE, ORIGIN, FUNCTIONING IN UKRAINIAN LANGUAGE

The main goal of our research is to collect, systematize and analyze the proper names of all seas that are in the Ukrainian language. The purpose of the research involves solving the following tasks: 1) to draw up a register of pelagonyms; 2) determine their denotative and characteristic features; 3) find out etymological and word-forming features; 4) describe the peculiarities of functioning in the Ukrainian language; 5) establish the defining features of this type of proper names. The object of analysis is 238 pelagonyms, and their denotative-characteristic, etymological-word-forming and functional features are the subject of analysis. In the process of analysis, we used genetic (to determine the origin of proper names), etymological (to find out the features of names creation), descriptive (to determine the extralingual features of pelagonyms), structural (to characterize the structure of names), functional (to describe features related to the functioning of seas names in texts of various styles) research methods and the method of quantitative calculations (to determine the productivity of different types of pelagonyms). It was established that compound constructions (the most productive models are "noun + adjective" and "noun + noun"), formed by a syntactic method, with combined motivation (in particular, locative-, memorial-, and qualitative-substantial) dominate, they are derived from onyms and appellatives. Geographical terms and anthroponyms or toponyms prevail in their composition. Most pelagonyms are ancient, hybrid, lowfrequency, emotionally neutral names that have a known and obscure etymology, are used in a scientific style, are elements of language (not speech), belong to the passive vocabulary, are unknown to the general public, and are devoid of ethnocultural meaning. In the future, we plan to pay attention to the general characteristics of other proper names: both open water bodies (for example, loughs or streams), and such categories as oikonyms, oronyms, or choronyms. Over time, this will make it possible to form a complete picture of the Ukrainian toponymy.

Epidemiological characteristics of fatal drowning and related factors in children in Zhejiang Province, 2022

Objective: To understand the epidemiological characteristics of fatal drowning in children in Zhejiang Province in 2022, analyze factors such as the swimming ability of children, the caregiver behavior at drowning site, types of first aid personnel and methods of first aid of unintentional fatal drowning and provide evidence for targeted intervention. Methods: Using the "Survey Form of Fatal Drowning Case in Children" designed by National Center for Chronic and Non-communicable Disease Control and Prevention of the China CDC, we collected case information of children aged 0-17 years who died due to drowning in Zhejiang in 2022 from medical history/death investigation records, telephone interviews, and home visits. Results: A total of 341 fatal drowning cases in children occurred in Zhejiang in 2022 and 330 cases were investigated (96.77%). The male to female of the cases was 2.33∶1, most cases were aged 15-17 years and 0-4 years, and 54.24% of fatal drowning cases occurred in children from other provinces. In the drowning cases, 83.33% were unintentional ones, and the proportion of intentional fatal drowning cases in children increased with age. Fatal drowning cases mainly occurred in open natural water bodies and public water storage facilities. More fatal drowning cases occurred in open natural water bodies in older children, while more fatal drowning cases occurred in public water storage facilities in younger children. In 275 children who died due to unintentional drowning, 73.09% could not swim, and only 1.09% were fully supervised by adults within an arm's length. First aid personnel, mainly medical staffs, bystanders and adult caregivers, were present for 47.63% fatal drowning cases. The proportion of the cases who had cardiopulmonary resuscitation as the first aid within 5 minutes was 2.18%. Conclusions: Drowning poses a serious threat to children's lives and there are differences in reasons and locations of fatal drowning in children in different age groups in Zhejiang Province in 2022. It is necessary to conduct to interventions to improve children's swimming skills, strengthen effective adult care and conduct health education about field first aid of drowning to reduce the incidence of drowning and related deaths in children.

Estimating the uncertainties of satellite derived soil moisture at global scale

This study attempts to derive the uncertainty of the soil moisture estimation from passive microwave satellite mission at global scale. To do so, the approach is based on the sensitivity of the Soil Moisture and Ocean Salinity (SMOS) soil moisture retrieval quality to the land surface characteristics within its footprint (presence of forest, topography, open water bodies, sand, clay, bulk density and soil organic carbon content). First, we performed a global assessment of SMOS using in situ measurements from the International Soil Moisture Network (ISMN) as reference, with more than 1900 ISMN stations and 10 years of SMOS data. This assessment shows that the ubRMSD scores vary greatly between locations (with a mean of 0.074 m3m−3 and an interquartile range of 0.030 m3m−3). Second, the scores are analyzed for different surface conditions within the satellite footprint. The best agreement between the ground measurement and SMOS time series are obtained for low forest cover, low topographic complexity, and marginal presence of open water bodies within the SMOS footprint. Soil parameters also have an impact, with better scores for sandier soils with a high bulk-density and low soil organic carbon content. Finally, we propose to extrapolate the obtained relationships, using a multiple linear regression, in order to derive a global map of SMOS uncertainties based on surface conditions. This map of predicted uncertainties show a diverse range of ubRMSD values across the globe (with a mean of 0.076 m3m−3 and an interquartile range of 0.031 m3m−3) depending on the surface characteristics. At the ISMN site location, the predicted ubRMSD shows similar results than the comparison between SMOS and the in situ measurements. The map of predicted SMOS ubRMSD represents an upper bound estimate of the SMOS uncertainty, as it includes the uncertainties of the in situ sensor measurements and the scale mismatch. Further investigations will focus on the different components of this uncertainty budget to obtain a better assessment of the absolute uncertainties of SMOS soil moisture retrievals across the globe.

Monitoring Changes in Parts of the Guinea-Savannah Woodlands

Land use and land cover (LULC) in Ghana has undergone a lot of changes over the past years emanating from natural and anthropogenic activities. This study is a comprehensive analysis of LULC changes in parts of the Guinea-Savannah through an integrated approach of geospatial procedures. Multi-temporal satellite imagery data sets of four different years, 1990 (Landsat TM), 2000 (Landsat ETM+), 2010 (Landsat ETM+) and 2020 (Landsat ETM+) were analyzed. Built-up area, Agricultural land, Closed savannah vegetation, Open savannah vegetation and Water bodies were LULC categories delineated for Jirapa municipality. The Cellular Automata-Markov (CA-Markov) model was applied to predict the likely changes in LULC in 2030. The study revealed that the most dominant land cover type in the municipality is the Open savannah vegetation as it occupied averagely 45% of the total surface area. Built-up area increased in area coverage by 93% between 1990 and 2020. Agricultural activities, bushfires, deforestation, infrastructural development, and population growth are the main drivers of changes in Agricultural land, Open savannah vegetation, Closed savannah vegetation and Water bodies. The LULC prediction for 2030 showed that the Built-up areas would increase significantly in 2030 leading to a 6% reduction in Agricultural land in 2030.

Monitoring Changes in Parts of the Guinea-Savannah Woodlands

Land use and land cover (LULC) in Ghana has undergone a lot of changes over the past years emanating from natural and anthropogenic activities. This study is a comprehensive analysis of LULC changes in parts of the Guinea-Savannah through an integrated approach of geospatial procedures. Multi-temporal satellite imagery data sets of four different years, 1990 (Landsat TM), 2000 (Landsat ETM+), 2010 (Landsat ETM+) and 2020 (Landsat ETM+) were analyzed. Built-up area, Agricultural land, Closed savannah vegetation, Open savannah vegetation and Water bodies were LULC categories delineated for Jirapa municipality. The Cellular Automata-Markov (CA-Markov) model was applied to predict the likely changes in LULC in 2030. The study revealed that the most dominant land cover type in the municipality is the Open savannah vegetation as it occupied averagely 45% of the total surface area. Built-up area increased in area coverage by 93% between 1990 and 2020. Agricultural activities, bushfires, deforestation, infrastructural development, and population growth are the main drivers of changes in Agricultural land, Open savannah vegetation, Closed savannah vegetation and Water bodies. The LULC prediction for 2030 showed that the Built-up areas would increase significantly in 2030 leading to a 6% reduction in Agricultural land in 2030.

Technical note: An open-source, low-cost system for continuous monitoring of low nitrate concentrations in soil and open water

Abstract. Nitrate (NO3-), mainly leaching with soil porewater, is the primary nonpoint source pollutant of groundwater worldwide. Obtaining real-time information on nitrate levels in soils would allow for gaining a better understanding of the sources and transport dynamics of nitrate through the unsaturated zone. However, conventional nitrate detection techniques (e.g., soil sample analysis) necessitate costly, laboratory-grade equipment for analysis, along with human resources, resulting in a laborious and time-intensive procedure. These drawbacks raise the need to develop cost-effective and automated systems for in situ nitrate measurements in field conditions. This study presents the development of a low-cost, portable, automated system for field measurements of nitrate in soil porewater and open water bodies. The system is based on the spectrophotometric determination of nitrate using a single reagent. The system design and processing software are openly accessible, including a building guide, to allow duplicating or changing the system according to user-specific needs. Three field tests, conducted over 5 weeks, validated the system's measurement capabilities within the range of 0–10 ppm NO3-–N with a low RMSE of <0.2 ppm NO3-–N when comparing the results to standard laboratory nitrate analysis. Data derived from such a system allow for tracking of the temporal variation in soil nitrate, thus opening new possibilities for diverse soil and nutrient management studies.

Evapotranspiration: A comprehensive review

Evapotranspiration (ET) is a fundamental process in the Earth’s water cycle, representing the combined movement of water from the land surface (including open water bodies, soil, and vegetation) back into the atmosphere. It encompasses two key components: evaporation, the direct transfer of water to the air from various surfaces, and transpiration, the loss of water vapor through tiny pores on plant leaves called stomata. This review provides a detailed examination of evapotranspiration, exploring its mechanisms, influencing factors, measurement techniques, and its significance in various environmental and agricultural applications. Moreover, a section on Irrigation under Climate change is included to understand the adaptation strategies.

Tracing Mine Water Flows in a Dolomite Quarry, South Africa, Using Hydrochemistry and Stable Isotopes

South Africa has a growing population, a relatively dry climate, and abundant mining activity, all of which increase the importance of water management. The Mooiplaas Dolomite Quarry, south east of Pretoria, has been mining metallurgical grade dolomite since 1969, within the productive karst aquifers of the Malmani Subgroup, Transvaal Supergroup. This study was conducted to elucidate the flow of water around the site, including the mine water and groundwater. The site was investigated by sampling precipitation, surface water, groundwater, and mine water for hydrochemical and stable isotope analysis from 2011 to 2017, totalling over 400 samples. Levels of nitrate in groundwater and mine water were marginally above drinking water limits, from explosives residues, and ammonia in the nearby Hennops River was unacceptably high due to municipal sewage outfalls, but otherwise, water quality was very good. Alkalinity from rock weathering, aided by crushing of dolomite, was the main control on water chemistry. Combined analysis of dissolved matter (TDS, nitrate, Mg, etc.) suggested that the dewatering of the mine and resultant recharge from the slimes dams caused an aerated zone of groundwater, which mixed with regional groundwater flowing beneath the site. Stable isotopes, with an evaporated signature from the mine open water bodies, also showed how mine operations cause recharge to groundwater and subsequent seepage back into the pit lakes. The mine appears not to contaminate the regional groundwater; however, mine designs should avoid situations where process water flows via groundwater back into pits, causing excessive dewatering costs.

Satellite Image Analysis Approach for Identifying Flood Impacts in DKI Jakarta

Jakarta, as the capital city of Indonesia, is one of the major cities in the world that is inevitably affected by disasters resulting from climate change. The topographical characteristics of Jakarta, situated in a low-lying area, make it susceptible to floods during the rainy season. In 2020, Jakarta experienced a rainfall of 377 mm/day, marking the highest precipitation during the period of 1866 to 2020. To mitigate the impact of flood disasters, the availability of flood distribution data is crucial. The process of identifying flood distribution utilizes Sentinel-1 radar satellite imagery with the Normalized Difference Sigma-Naught Index (NDSI) method. NDSI is sensitive to open water bodies due to changes in land surface properties during floods. Based on NDSI analysis, the flood distribution in DKI Jakarta was identified on January 2, 2020, covering 17,38% of the total area of DKI Jakarta, which is 661,52 km2.

Utilizing Aerial Photography to Trace the Development of Urbanization in the Chennai District

Chennai, India is growing more urbanized by the day, hence studying its development is essential. We may see the world from a bird's-eye viewpoint thanks to aerial photography, a method for taking pictures of the Earth's surface from an elevated position—typically from an aircraft or drone. Scientific research, land surveying, urban planning, environmental monitoring, and mapping are just a few of the applications for these photos. Using remote sensing techniques, we are able to examine and record changes in Chennai's physical terrain over time, allowing us to trace the city's evolution through these aerial photos. ArcGIS, ERDAS, ENVI, Pix4D, Global Mapper, and QGIS were among the programs we used to process and examine the aerial photo data. Through the help of these software programs, users can extract insightful data and useful information from photos taken by satellites, drones, or airplanes. When compared to satellite images, aerial photography frequently produces imagery with a better spatial resolution, enabling more accurate and thorough study of ground-based objects. Through a comparative analysis of maps produced using aerial photography data throughout time, we have discovered that Chennai is losing open land, green spaces, and water bodies because of its growing urbanization. By closely analysing this trend and taking into account various factors, we can forecast the continued growth of Chennai.

Application of surface energy balance Algorithm for land (SEBAL) for mapping spatiotemporal evapotranspiration over various climatic zones of Pakistan

To address the emerging issues of water scarcity in a hydrological realm, estimation of evapotranspiration (ET) at spatiotemporal scale is essential. It is crucial for understanding climate change, particularly for Pakistan's ongoing water resource management policy under the United Nations' Sustainable Development Goals (SDGs), where water is given top priority. In situ techniques can quantify ET, but with a small spatial footprint, it cannot accurately depict its regional distribution. Therefore, geospatial techniques and data, especially high resolution satellite imagery, estimate ET for large heterogeneous surfaces. The Surface Energy Balance Algorithm for Land (SEBAL) was employed in this study to estimate the spatiotemporal distribution of ET in various climatic zones of Pakistan using Landsat 8 images. A total of 48 satellite images were processed for six study sites (Skardu, Kalam, Peshawar, D.I. Khan, Quetta and Tando Jam) for the summer months from 2013 to 2020. Accuracy of SEBAL-based ET was evaluated with ground-based ET. The model performs well with daily rate of ET under southern desert hot climate of Tando Jam with highest pearson’s correlation coefficient (r) of 0.89, lowest root mean squared difference (RMSD) and mean bias error (MBE) of 0.42 mm/day and 0.26 mm/day, respectively. The steppe-hot and extremely humid climate of Peshawar follow Tando Jam, with r value of 0.82, RMSD value of 0.76 mm/day, and MBE value of 0.40 mm/day. Central desert hot climate of Dera Ismail Khan(D.I. Khan) has the lowest (though still better) r value at 0.74, while the other two indices (RMSD and MBE) do not differ significantly from other sites. A high RMSD (0.84 mm/day) for the daily ET rate is recorded in Skardu's northern, cold, snowy climate; the rest of the indices are comparable to D.I. Khan region. In Kalam, the ET rate for various land uses was calculated and was found highest for snow cover (4.66 to 6.45 mm/day), followed by forest cover (3.69 to 5.79 mm/day), and open water body (3.25 to 5.25 mm/day). The SEBAL model exhibitedtremendous potential to be applied under a range of climatic conditionsin this study. Evapotranspiration can provide vital information for monitoring hydrological extremes (droughts and floods), environmental protection, planning climate-resilient agriculture, combating climate change, and sustainable management of water resources.

Mechanistic study of the electrochemical oxidation of fluoroquinolones: Ciprofloxacin, danofloxacin, enoxacin, levofloxacin and lomefloxacin

The fluoroquinolones ciprofloxacin, danofloxacin, enoxacin, levofloxacin and lomefloxacin, occur in water bodies worldwide and therefore pose a threat to the aquatic environment. Advanced purification procedures, such as electrochemical oxidation, may act as a remedy since they contribute to eliminating contaminants and prevent micropollutants from entering open water bodies. By electrochemical treatment in a micro-flow reactor equipped with a boron-doped diamond (BDD) electrode, the fluoroquinolones were efficiently degraded. A total of 15 new products were identified using high-performance high-resolution chromatography coupled with high-resolution multifragmentation mass spectrometry. The ecotoxicity of the emerging transformation products was estimated through in silico quantitative structure activity relationship analysis. Almost all transformation products were predicted less ecotoxic than the initial compounds. The fluoroquinolone degradation followed three major mechanisms depending on the voltage during the electrochemical oxidation. At approximately 1 V, the reactions started with the elimination of molecular hydrogen from the piperazine moiety. At approx. 1.25 V, methyl and methylene groups were eliminated. At 1.5 V, hydroxyl radicals, generated at the BDD electrode, led to substitution at the piperazine ring. This novel finding of the three reactions depending on voltage contributes to the mechanistic understanding of electrochemical oxidation as potential remedy against fluoroquinolones in the aquatic environment.

DESIGN AND FABRICATION OF CUTTING-EDGE PLASTIC BOTTLE CAP PRESS TOOLS FOR A GREENER FUTURE

Waste is the result of human activity which puts great pressure on the environment, especially when waste is not collected and ends up piling up in open places and water bodies. Waste management can generally be done by burning it, throwing it into ditches, landfilling it and most often throwing it into rivers. This design aims to deal with plastic waste by recycling it. The method used is a melting system using a microwave, while pressing uses a hydraulic jack. The use of this tool is to recycle the waste and process it into something that has use and sale value. The results of this bottle cap recycling tool convert plastic bottle cap waste into furniture material, in the form of coasters. The jack used in this tool has a capacity of 10 tons. In tests carried out on 125g bottle caps, they melted for 60 minutes at a temperature of 250°C.

What is there to drink? Water (in)justice in the democratic South Africa

IntroductionAligned to Chapter 2 of the Constitution of the Republic of South Africa which recognizes water to be a basic human right, the democratic government from 1994 adopted policies, legislation and programmes that encourage universal access to basic water services. Although some progress has been made in urban areas concerning access to potable water supply, South Africa still faces serious problems in providing basic water services in rural areas. This study aims to understand sources of drinking water, how water is accessed by local communities, and determine the barriers associated with access to potable water and management in the rural villages of Madiba and Enqabeni.Data collectionTo fulfil the aim of this study, semi-structured interviews, interviewer-administered questionnaires, and field observations were employed as data collection tools. Data obtained from interviews were analyzed using thematic content analysis, while the questionnaires were assessed using Statistical Package for Social Sciences.Results and DiscussionThe study found that the majority of people still rely on untreated water from open water bodies. The study also identified corruption, and infrastructural and institutional problems as barriers affecting water service delivery to communities. These institutional problems mean that water resource management and access are unfair, inequitable and unjust, and constitute water injustice. The basic human right of access to water by communities is thereby violated and this has devastating effects on the lives and livelihoods of community members. Despite democracy, the legacy of apartheid's unequal water policy is still influencing water services and South Africa remains far from achieving Sustainable Development Goal 6.

Habitat Preference of Lesser Whistling Ducks (Dendrocygna javanica) in Selected Wetlands within Colombo Ramsar Wetland City

Lesser Whistling Ducks (LWD) (Dendrocygna javanica) mostly occur in flocks and inhabit lakes, ponds and marshes within freshwater wetlands. They feed mainly on plants taken from water (seed, shoots, tuber and leaves), vertebrates (fishes) and invertebrates (mollusks and worms). In this study, habitat preference of LWD in five selected wetlands in Colombo Ramsar Wetland City (CRWC); Beddagana Wetland Park (BWP), Diyasaru Park (DP), Heen Ela Marsh (HEM), Thalangama Marsh (TM) and Kimbulawala Wetland (KW) was studied from May 2021 to April 2022 as wetlands in urban areas act as the last resort for many resident and migratory bird species and play a major role in the assemblage and conservation of water birds. Habitats present in the selected wetlands were categorized as open water body, floating vegetation, trees, grassland, paddy field, shrubs, bare land. Percentage cover of each habitat type at each sampling site were estimated using quadrat method. LWD were surveyed using line transects of 100m in length, laid in each selected study site to cover representative habitats and observations were made up to 30m towards either side of each transect. Sampling was done in three time slots of the day, morning, mid-day and evening. Floating vegetation, open water body and grassland were the preferred habitat types of D. javanica in BWP, DP, HEM and TM. LWD were not recorded in KW. Floating vegetation (54.97%) was the most preferred habitat by LWD in each study site followed by open water body (24.70%) and grassland (15.82%) habitat types. Eicchornia crassipes (Common water hyacinth) and Salvinia molesta (Giant salvinia) were their most preferred floating vegetation type. Higher abundance of LWD was recorded in TM (83.22%) followed by DP (9.17%), BWP (4.16%) and HEM (3.45%). TM which had higher abundance of LWD had higher floating vegetation coverage (28%) and was rich with E. crassipes and S. molesta. Present study revealed that, LWD mostly used E. crassipes and S. molesta as their main foraging and resting sites. Management of invasive alien species have been undertaken in Colombo wetlands and as E. crassipes and S. molesta are alien species they are currently being removed. Therefore, outright removal of E. crassipes and S. molesta may not be suitable and a monitored removal program that will conserve this habitat type should be implemented in order to conserve the habitats preferred by LWD in CRWC. 
 Keywords: Lesser whistling ducks, Wetlands, Habitat preference

Automatic mapping of 500 m daily open water body fraction in the American continent using GOES-16 ABI imagery

Timely and large-area monitoring of terrestrial water bodies using remote sensing data is essential to protect water resource security for humans and ecosystems. Although efforts have been made to monitor inter-monthly water bodies at the regional, continental and global scales, surface open water bodies may experience rapid changes within a short duration. At the same time, the data gaps caused by the long revisit frequencies of satellite sensor imaging systems and the extremely cloudy and rainy weather in certain areas mean that a suitable operational method for recording such rapid changes over large areas does not yet exist. The recently launched operational geostationary satellite sensor GOES-16 ABI can provide multi-scale optical images every 10 min in the Americas, and it has great potential to provide a new solution for timely open surface water monitoring. In this research, a framework based on a multi-scale non-linear mixture model (NLMM) was proposed for the automatic estimation of 500 m daily open water body fraction maps across the full extent of the American continent from GOES-16 ABI imagery. Specifically, an exterior spectral library was created firstly from many pairs of training GOES-16 ABI images and 500 m water body fraction maps derived from Landsat images, and an inherited interior pure spectral library was then derived from a pair of the testing GOES-16 ABI image and the corresponding pure water and non-water (i.e., vegetation and soil/rock substrate) fractions extracted from the monthly water recurrence dataset. Furthermore, a synthetic interior mixed spectral library was built finally based on the linear and non-linear mixtures of randomly selected pure endmembers of water and non-water (i.e., vegetation and soil/rock substrate) in the testing image. All the exterior and interior pure and synthetic mixed spectral libraries were employed jointly in the NLMM machine learning method for estimating daily water body fractions with GOES-16 ABI images. Experiments show that the integration of all three different spectral libraries produced 500 m open water body fraction maps with the greatest accuracies. Compared to traditional linear spectral unmixing and a water index thresholding method, the proposed method produced more accurate results both quantitatively and visually. Moreover, the proposed method can produce time-series daily 500 m open water body fraction maps with minimal cloud coverage for the full extent of the Americas by combining dense GOES-16 ABI images at half-hour intervals, opening up great possibilities for near real-time rapid open water body changes monitoring, such as flooding and drought, over large areas, even with a high frequency of cloud cover.

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.