scholarly journals Colour Classification of 1486 Lakes across a Wide Range of Optical Water Types

2018 ◽  
Vol 10 (8) ◽  
pp. 1273 ◽  
Author(s):  
Moritz Lehmann ◽  
Uyen Nguyen ◽  
Mathew Allan ◽  
Hendrik van der Woerd
Keyword(s):  
Water Quality ◽  
Environmental Control ◽  
Anthropogenic Factors ◽  
Landsat 8 ◽  
Diverse Range ◽  
Water Colour ◽  
Water Types ◽  
Wide Range ◽  
Yellow Orange ◽  
Spatio Temporal

Remote sensing by satellite-borne sensors presents a significant opportunity to enhance the spatio-temporal coverage of environmental monitoring programmes for lakes, but the estimation of classic water quality attributes from inland water bodies has not reached operational status due to the difficulty of discerning the spectral signatures of optically active water constituents. Determination of water colour, as perceived by the human eye, does not require knowledge of inherent optical properties and therefore represents a generally applicable remotely-sensed water quality attribute. In this paper, we implemented a recent algorithm for the retrieval of colour parameters (hue angle, dominant wavelength) and derived a new correction for colour purity to account for the spectral bandpass of the Landsat 8 Operational Land Imager (OLI). We used this algorithm to calculate water colour on almost 45,000 observations over four years from 1486 lakes from a diverse range of optical water types in New Zealand. We show that the most prevalent lake colours are yellow-orange and blue, respectively, while green observations are comparatively rare. About 40% of the study lakes show transitions between colours at a range of time scales, including seasonal. A preliminary exploratory analysis suggests that both geo-physical and anthropogenic factors, such as catchment land use, provide environmental control of lake colour and are promising avenues for future analysis.

Unified, high resolution water quality retrievals from Earth Observation satellites

2021 ◽  
Author(s):  
James Harding
Keyword(s):  
Water Quality ◽  
Water Resource Management ◽  
State Of The Art ◽  
Earth Observation ◽  
Water Quality Parameter ◽  
Landsat 8 ◽  
Optical Parameters ◽  
Atmospheric Conditions ◽  
Mixture Density ◽  
Wide Range

<p>Earth Observation (EO) satellites are drawing considerable attention in areas of water resource management, given their potential to provide unprecedented information on the condition of aquatic ecosystems. Despite ocean colours long history; water quality parameter retrievals from shallow and inland waters remains a complex undertaking. Consistent, cross-mission retrievals of the primary optical parameters using state-of-the-art algorithms are limited by the added optical complexity of these waters. Less work has acknowledged their non- or weakly optical parameter counterparts. These can be more informative than their vivid counterparts, their potential covariance would be regionally specific. Here, we introduce a multi-input, multi-output Mixture Density Network (MDN), that largely outperforms existing algorithms when applied across different bio-optical regimes in shallow and inland water bodies. The model is trained and validated using a sizeable historical database in excess of 1,000,000 samples across 38 optical and non-optical parameters, spanning 20 years across 500 surface waters in Scotland. The single network learns to predict concurrently Chlorophyll-a, Colour, Turbidity, pH, Calcium, Total Phosphorous, Total Organic Carbon, Temperature, Dissolved Oxygen and Suspended Solids from real Landsat 7, Landsat 8, and Sentinel 2 spectra. The MDN is found to fully preserve the covariances of the optical and non-optical parameters, while known one-to-many mappings within the non-optical parameters are retained. Initial performance evaluations suggest significant improvements in Chl-a retrievals from existing state-of-the-art algorithms. MDNs characteristically provide a means of quantifying the noise variance around a prediction for a given input, now pertaining to real data under a wide range of atmospheric conditions. We find this to be informative for example in detecting outlier pixels such as clouds, and may similarly be used to guide or inform future work in academic or industrial contexts. </p>

scholarly journals WATER CLARITY MAPPING IN KERINCI AND TONDANO LAKE WATERS USING LANDSAT 8 DATA

2017 ◽  
Vol 12 (2) ◽  
pp. 117 ◽  
Author(s):  
Bambang Trisakti ◽  
Nana Suwargana ◽  
I Made Parsa
Keyword(s):  
Water Quality ◽  
Lake Water ◽  
Atmospheric Correction ◽  
Total Suspended Solid ◽  
Water Clarity ◽  
Suspended Solid ◽  
Lake Ecosystem ◽  
Landsat 8 ◽  
Wide Range ◽  
Lake Waters

Land conversion occurred in the lake catchment area caused the decreasing of water quality in many lakes of Indonesia. According to Lake Ecosystem Management Guidelines from Ministry of Environment, tropic state of lake water is one of parameters for assessing the lake ecosystem status. Tropic state can be indicated by the quantity of nitrogen, phosphorus, chlorophyll, and water clarity. The objective of this research is to develop the water quality algorithm and map the water clarity of lake water using Landsat 8 data. The data were standardized for sun geometry correction and atmospheric correction using Dark Object Subtraction method. In the first step, Total Suspended Solid (TSS) distributions in the lake were calculated using a semi empirical algorithm (Doxaran et al., 2002), which can be applied to a wide range of TSS values. Secchi Disk Transparency (SDT) distributions were calculated using our water clarity algorithm that was obtained from the relationship between TSS and SDT measured directly in the lake waters. The result shows that the water clarity algorithm developed in this research has the determination coefficient that reaches to 0,834. Implementation of the algorithm for Landsat 8 data in 2013 and 2014 showed that the water clarity in Kerinci Lake waters was around 2 m or less, but the water clarity in Tondano Lake waters was around 2 – 3 m. It means that Kerinci Lake waters had lower water clarity than Tondano Lake waters which is consistent with the field measurement results.

scholarly journals Assessing the potential of integrating Landsat sensors for estimating chlorophyll-a concentration in a reservoir

2017 ◽  
Vol 49 (5) ◽  
pp. 1608-1617 ◽  
Author(s):  
Matias Bonansea ◽  
Claudia Rodriguez ◽  
Lucio Pinotti
Keyword(s):  
Water Quality ◽  
Chlorophyll A ◽  
Landsat Imagery ◽  
Quality Parameters ◽  
Landsat 8 ◽  
Chlorophyll A Concentration ◽  
Chl A ◽  
Sensing Applications ◽  
Wide Range ◽  
Quality Assessments

Abstract Landsat satellites, 5 and 7, have significant potential for estimating several water quality parameters, but to our knowledge, there are few investigations which integrate these earlier sensors with the newest and improved mission of Landsat 8 satellite. Thus, the comparability of water quality assessing across different Landsat sensors needs to be evaluated. The main objective of this study was to assess the feasibility of integrating Landsat sensors to estimate chlorophyll-a concentration (Chl-a) in Río Tercero reservoir (Argentina). A general model to retrieve Chl-a was developed (R2 = 0.88). Using observed versus predicted Chl-a values the model was validated (R2 = 0.89) and applied to Landsat imagery obtaining spatial representations of Chl-a in the reservoir. Results showed that Landsat 8 can be combined with Landsat 5 and 7 to construct an empirical model to estimate water quality characteristics, such as Chl-a in a reservoir. As the number of available and upcoming sensors with open access will increase with time, we expect that this trend will certainly further promote remote sensing applications and serve as a valuable basis for a wide range of water quality assessments.

scholarly journals Extending Landsat 8: Retrieval of an Orange contra-Band for Inland Water Quality Applications

2020 ◽  
Vol 12 (4) ◽  
pp. 637 ◽  
Author(s):  
Alexandre Castagna ◽  
Stefan Simis ◽  
Heidi Dierssen ◽  
Quinten Vanhellemont ◽  
Koen Sabbe ◽  
...  
Keyword(s):  
Water Quality ◽  
Atmospheric Correction ◽  
Cyanobacterial Bloom ◽  
Quality Parameters ◽  
Retrieval Algorithm ◽  
Percentage Error ◽  
Landsat 8 ◽  
Base Line ◽  
Band Ratio ◽  
Water Types

The Operational Land Imager (OLI) onboard Landsat 8 has found successful application in inland and coastal water remote sensing. Its radiometric specification and high spatial resolution allows quantification of water-leaving radiance while resolving small water bodies. However, its limited multispectral band set restricts the range of water quality parameters that can be retrieved. Identification of cyanobacteria biomass has been demonstrated for sensors with a band centered near 620 nm, the absorption peak of the diagnostic pigment phycocyanin. While OLI lacks such a band in the orange region, superposition of the available multispectral and panchromatic bands suggests that it can be calculated by a scaled difference. A set of 428 in situ spectra acquired in diverse lakes in Belgium and The Netherlands was used to develop and test an orange contra-band retrieval algorithm, achieving a mean absolute percentage error of 5.39% and a bias of −0.88% in the presence of sensor noise. Atmospheric compensation error propagated to the orange contra-band was observed to maintain about the same magnitude (13% higher) observed for the red band and thus results in minimal additional effects for possible base line subtraction or band ratio algorithms for phycocyanin estimation. Generality of the algorithm for different reflectance shapes was tested against a set of published average coastal and inland Optical Water Types, showing robust retrieval for all but relatively clear water types (Secchi disk depth > 6 m and chlorophyll a < 1.6 mg m − 3 ). The algorithm was further validated with 79 matchups against the Ocean and Land Colour Imager (OLCI) orange band for 10 globally distributed lakes. The retrieved band is shown to convey information independent from the adjacent bands under variable phycocyanin concentrations. An example application using Landsat 8 imagery is provided for a known cyanobacterial bloom in Lake Erie, US. The method is distributed in the ACOLITE atmospheric correction code. The contra-band approach is generic and can be applied to other sensors with overlapping bands. Recommendations are also provided for development of future sensors with broad spectral bands with the objective to maximize the accuracy of possible spectral enhancements.

A Landsat 8 OLI Satellite Data-Based Assessment of Spatio-Temporal Variations of Lake Sevan Phytoplankton Biomass

2017 ◽  
Vol 17 (1) ◽  
pp. 83-89 ◽  
Author(s):  
Garegin Tepanosayn ◽  
Vahagn Muradyan ◽  
Azatuhi Hovsepyan ◽  
Lilit Minasyan ◽  
Shushanik Asmaryan
Keyword(s):  
Water Quality ◽  
Phytoplankton Biomass ◽  
Atmospheric Correction ◽  
In Situ Measurements ◽  
Biomass Estimation ◽  
Landsat 8 ◽  
Landsat 8 Oli ◽  
Phytoplankton Communities ◽  
Spatio Temporal

Abstract The Sevan is one of the world’s largest highland lakes and the largest drinking water reservoir to the South Caucasus. An intensive drop in the level of the lake that occurred over the last decades of the 20th century has brought to eutrophication. The 2000s were marked by an increase in the level of the lake and development of fish farming. To assess possible effect of these processes on water quality, creating a state-ofthe- art water quality monitoring system is required. Traditional approaches to monitoring aquatic systems are often time-consuming, expensive and non-continuous. Thus, remote sensing technologies are crucial in quantitatively monitoring the status of water quality due to the rapidity, cyclicity, large-scale and low-cost. The aim of this work was to evaluate potential applications of the Landsat 8 Operational Land Imager (OLI) to study the spatio-temporal phytoplankton biomass changes. In this study phytoplankton biomasses are used as a water quality indicator, because phytoplankton communities are sensitive to changes in their environment and directly correlated with eutrophication. We used Landsat 8 OLI (30 m spatial resolution, May, Aug, Sep 2016) images converted to the bottom of atmosphere (BOA) reflectance by performing standard preprocessing steps (radiometric and atmospheric correction, sun glint removal etc.). The nonlinear regression model was developed using Landsat 8 (May 2016) coastal blue, blue, green, red, NIR bands, their ratios (blue/red, red/green, red/blue etc.) and in situ measurements (R2=0.7, p<0.05) performed by the Scientific Center of Zoology and Hydroecology of NAS RA in May 2016. Model was applied to the OLI images received for August and September 2016. The data obtained through the model shows that in May the quantity of phytoplankton mostly varies from 0.2 to 0.6g/m3. In August vs. May a sharp increase in the quantity of phytoplankton around 1-5 g/m3 is observable. In September, very high contents of phytoplankton are observed for almost entire surface of the lake. Preliminary collation between data generated with help of the model and in-situ measurements allows to conclude that the RS model for phytoplankton biomass estimation showed reasonable results, but further validation is necessary.

scholarly journals Challenges for Water Quality Protection in the Greater Metropolitan Area of Addis Ababa and the Upper Awash Basin, Ethiopia –Time to Take Stock

2020 ◽  
Author(s):  
Melaku Getachew ◽  
Worku Legesse Mulat ◽  
Seid Tiku Mereta ◽  
Geremew Sahilu Gebrie ◽  
Mary Kelly-Quinn
Keyword(s):  
Water Pollution ◽  
Water Quality ◽  
Waste Management ◽  
Metropolitan Area ◽  
Addis Ababa ◽  
Mitigation Measures ◽  
Anthropogenic Factors ◽  
Human Consumption ◽  
Rapid Urbanization ◽  
Wide Range

Ethiopia, the second-most populous country in Africa after Nigeria, has more than one hundred million people and is one of the world’s fastest-growing countries in terms of economy. It has 12 major river basins with an annual renewable flow of 122 billion m3. The country is facing increasing pressures on water resources both in terms of quantity and quality. Many researchers have highlighted that water pollution is severe and increasing particularly in the environs of Addis Ababa because of complex anthropogenic factors. The objective of this review was to synthesize the key results of research to date on the water quality in the environs of Addis Ababa and use that information to highlight management gaps, challenges and future research needs. According to the studies reviewed, water pollution pressures result from rapid urbanization and industrial expansion without adequate solid waste management and wastewater treatment facilities and agricultural activities. The problems are compounded by law enforcement difficulties. Trace metal contamination of rivers, streams, reservoirs and their bioaccumulation in vegetables highlight the urgency of addressing water pollution in the catchment. Most studies agreed that water from reservoirs, rivers and streams in the environs of Addis Ababa is unfit for human consumption as it contains a wide range of pollutants that could affect community health. Hence effective pollution detection, mitigation measures, and monitoring including the development of bioassessment tools, together with cost-effective management measures are urgently required to reverse the decline in water quality in Ethiopia in general and in the greater metropolitan area of Addis Ababa and the upper Awash basin in particular. Keywords: Addis Ababa, Metropolitan, Waste management, Upper Awash basin, Water quality

scholarly journals Diversity II water quality parameters for 300 lakes worldwide from ENVISAT (2002–2012)

2018 ◽  
Author(s):  
Daniel Odermatt ◽  
Olaf Danne ◽  
Petra Philipson ◽  
Carsten Brockmann
Keyword(s):  
Water Quality ◽  
Large Data ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Wide Range ◽  
Floating Vegetation ◽  
Vegetation Maps ◽  
Spatio Temporal ◽  
Reference Measurements ◽  
Data Layers

Abstract. The use of ground sampled water quality information for global studies is limited due to practical and financial constraints. Remote sensing is a valuable means to overcome such limitations and to provide synoptic views of ambient water quality at appropriate spatio-temporal scales. In past years several large data processing efforts were initiated to provide corresponding data sources. The Diversity II water quality dataset consists of several monthly, yearly and 9-year averaged water quality parameters for 340 lakes worldwide and is based on data from the full ENVISAT MERIS operation period (2002–2012). Existing retrieval methods and datasets were selected after an extensive algorithm intercomparison exercise using in situ reference measurements for more than 40 lakes representing a wide range of bio-optical conditions. Chlorophyll-a, total suspended matter, turbidity, coloured dissolved organic matter, lake surface water temperature, cyanobacteria and floating vegetation maps, as well as several auxiliary data layers, provide a generically specified data basis that can be used for assessing a variety of locally relevant ecosystem properties and environmental problems. We demonstrate the use of the products by illustrating and discussing remotely sensed evidence of lake-specific processes and prominent regime shifts documented in literature. The Diversity II data are available from https://doi.pangaea.de/10.1594/PANGAEA.871462, and Python scripts for their analysis and visualization are provided at https://github.com/odermatt/diversity/.

scholarly journals Sustaining enhanced condensation on hierarchical mesh-covered surfaces

2018 ◽  
Vol 5 (6) ◽  
pp. 878-887 ◽  
Author(s):  
Rongfu Wen ◽  
Shanshan Xu ◽  
Dongliang Zhao ◽  
Lixin Yang ◽  
Xuehu Ma ◽  
...  
Keyword(s):  
Large Scale ◽  
Environmental Control ◽  
Phase Interface ◽  
Industrial Applications ◽  
Droplet Growth ◽  
Diverse Range ◽  
Nanostructured Surfaces ◽  
Wide Range ◽  
Solid Liquid ◽  
Liquid Condensate

Abstract Controlling the solid–liquid–vapor tri-phase interface is of fundamental importance for a broad range of industrial applications including biomedical engineering, energy production and utilization, environmental control, water production, and thermal management. Although a lot of progress has been made over the past few decades on surface manipulation for promoting droplet removal, it is challenging to accelerate both droplet growth and surface refreshing for enhancing vapor-to-liquid condensation. Here we present a superhydrophobic hierarchical mesh-covered (hi-mesh) surface to enable continuous sucking flow of liquid condensate, which achieves fourfold-higher droplet growth and 36.8% faster surface refreshing compared to the state-of-the-art dropwise condensation. Unprecedented enhanced condensation heat transfer is observed to be sustained over a wide range of surface subcooling on the hi-mesh surfaces. This demonstration of sustained enhanced condensation enhancement is not only of fundamental scientific importance, but also provides a viable strategy for large-scale deployment of micro/nanostructured surfaces in a diverse range of technologies.

Nine Centuries of Man

2017 ◽  
Keyword(s):  
Twentieth Century ◽  
Diverse Range ◽  
Gender Expectations ◽  
Court Records ◽  
The Past ◽  
Wide Range ◽  
Police Reports ◽  
Late Twentieth ◽  
Scottish History ◽  
Late Twentieth Century

What did it mean to be a man in Scotland over the past nine centuries? Scotland, with its stereotypes of the kilted warrior and the industrial ‘hard man’, has long been characterised in masculine terms, but there has been little historical exploration of masculinity in a wider context. This interdisciplinary collection examines a diverse range of the multiple and changing forms of masculinities from the late eleventh to the late twentieth century, exploring the ways in which Scottish society through the ages defined expectations for men and their behaviour. How men reacted to those expectations is examined through sources such as documentary materials, medieval seals, romances, poetry, begging letters, police reports and court records, charity records, oral histories and personal correspondence. Focusing upon the wide range of activities and roles undertaken by men – work, fatherhood and play, violence and war, sex and commerce – the book also illustrates the range of masculinities that affected or were internalised by men. Together, the chapters illustrate some of the ways Scotland’s gender expectations have changed over the centuries and how, more generally, masculinities have informed the path of Scottish history

Diversity and Integration in Private International Law

2019 ◽  
Keyword(s):  
South America ◽  
International Law ◽  
Value Systems ◽  
Private International Law ◽  
Diverse Range ◽  
Cross Border ◽  
Wide Range ◽  
Depth Analysis ◽  
And Shifts ◽  
Substantive Law

This book opens a cross-regional dialogue and shifts the Eurocentric discussion on diversity and integration to a more inclusive engagement with South America in private international law issues. It promotes a contemporary vision of private international law as a discipline enabling legal interconnectivity, with the potential to transcend its disciplinary boundaries to further promote the reality of cross-border integration, with its focus on the ever-increasing cross-border mobility of individuals. Private international law embraces legal diversity and pluralism. Different legal traditions continue to meet, interact and integrate in different forms, at the national, regional and international levels. Different systems of substantive law couple with divergent systems of private international law (designed to accommodate the former in cross-border situations). This complex legal landscape impacts individuals and families in cross-border scenarios, and international commerce broadly conceived. Private international law methodologies and techniques offer means for the coordination of this constellation of legal orders and value systems in cross-border situations. Bringing together world-renowned academics and experienced private international lawyers from a wide range of jurisdictions in Europe and South America, this edited collection focuses on the connective capabilities of private international law in bridging and balancing legal diversity as a corollary for the development of integration. The book provides in-depth analysis of the role of private international law in dealing with legal diversity across a diverse range of topics and jurisdictions.

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