Status Of Water Bodies Research Articles

Probability of misclassifying biological elements in surface waters

Measurement uncertainties are inherent to assessment of biological indices of water bodies. The effect of these uncertainties on the probability of misclassification of ecological status is the subject of this paper. Four Monte-Carlo (M-C) models were applied to simulate the occurrence of random errors in the measurements of metrics corresponding to four biological elements of surface waters: macrophytes, phytoplankton, phytobenthos, and benthic macroinvertebrates. Long series of error-prone measurement values of these metrics, generated by M-C models, were used to identify cases in which values of any of the four biological indices lay outside of the “true” water body class, i.e., outside the class assigned from the actual physical measurements. Fraction of such cases in the M-C generated series was used to estimate the probability of misclassification. The method is particularly useful for estimating the probability of misclassification of the ecological status of surface water bodies in the case of short sequences of measurements of biological indices. The results of the Monte-Carlo simulations show a relatively high sensitivity of this probability to measurement errors of the river macrophyte index (MIR) and high robustness to measurement errors of the benthic macroinvertebrate index (MMI). The proposed method of using Monte-Carlo models to estimate the probability of misclassification has significant potential for assessing the uncertainty of water body status reported to the EC by the EU member countries according to WFD. The method can be readily applied also in risk assessment of water management decisions before adopting the status dependent corrective actions.

The influence of flow permanence and drying pattern on macroinvertebrate biomonitoring tools used in the assessment of riverine ecosystems

Temporary rivers comprise a significant proportion of river networks globally and their prevalence is expected to increase as a result of future climate change and anthropogenic water resource pressures. Despite this, the influence of drying events on freshwater biomonitoring tools within temporary rivers has received limited research attention within temperate environments. This study examines the effects of flow permanence and longitudinal drying patterns on selected biomonitoring indices used within the United Kingdom to assess the ecological status of waterbodies within the context of the Water Framework Directive. These indices are based on faunal tolerances and preferences to nutrient enrichment (BMWP, ASPT and Ntaxa) and flow velocity (Family LIFE). Long-term biomonitoring data from four rivers within southern England were examined, two of which dry longitudinally from the headwaters and two that dry within the mid-reaches. The results demonstrate that all of the biomonitoring indices examined differed significantly between each ‘hydrological class’ (i.e. temporary versus perennial reaches), with those based on absolute scores (BMWP and Ntaxa) displaying greater differences compared to those derived using scores standardized by the number of taxa recorded (ASPT and Family LIFE). The individual influence of drying pattern did not have a significant effect on any biomonitoring index. However, the interaction between the hydrological class and drying pattern significantly influenced all biomonitoring indices, indicating that the effect of flow intermittency on the metrics examined differed between drying patterns. Flow permanence explained a greater amount of statistical variation compared to the hydrological class and highlights the importance of the duration of flowing conditions on biomonitoring indices. The results indicate that flow intermittency has a significant effect on freshwater biomonitoring tools and highlights the need to incorporate this knowledge into existing management and environmental policy frameworks to prevent the misclassification of the ecological status of temporary streams.

First assessment of the ecological status in the Levant Basin: Application of the CARLIT index along the Lebanese coastline

Macroalgae is one of the Biological Quality Elements (BQE) used by several indexes conceived in the European Water Framework Directive (WFD) for the assessment of the Ecological status of coastal water bodies. Among them, CARLIT index, based on the cartography of rocky-shore littoral communities, has been extensively and successfully applied in the Western Mediterranean Sea. In this study CARLIT was applied for the first time in the Levantine Sea, along the Lebanese shoreline in order to test the suitability of this method in the peculiar ecological conditions of the Levantine Sea and have a first assessment of its ecological status. The choice of proper reference sites is a focal point in the fulfillment of the WFD. In order to ensure accurate calculation of the ecological status of the Lebanese coast, the calculations of the reference conditions (RC) were performed using the values calculated in the Lebanese reference area, the Northwestern (NW) Mediterranean RC proposed in the first application of the CARLIT method and the Adriatic Sea RC. The results showed that the calculated ecological quality ratio values (EQR) based on Lebanese RC is particularly important when considering the principle of the WFD to reach and maintain a good Ecological Status. Overall, the EQR values were well correlated with anthropogenic pressures, as assessed by the LUSI and MA-LUSI indexes. In addition, this method allowed the collection of accurate information on the distribution and abundance of shallow-water communities, especially of those deserving protection (e.g. Cystoseira forests). Thus, the present paper represents a baseline for future studies and gives useful tools for the management of human impacts on the Lebanese coast.

An Empirical Model for River Ecological Management with Uncertainty Evaluation

River Basin District Authorities make use of water quality models in order to assess the environmental status of water bodies. The current Italian procedure aiming to classify the ecological status of a watercourse employs the quality assessment of four biological elements with the support of some chemical and physical elements. Since many measures of the Directive 2000/60/CE affect the chemical and physical elements of the river, the Tiber River Basin Authority (TRBA) has designed an empirical model linking the anthropogenic pressures, the chemical and physical elements of impacts and river biological quality elements. The general model is named PARBLEU, which stands for Pressures/impacts/responses Assessment into River Basins Leading to Environmental Uses. In the present manuscript, only a sub-model of PARBLEU (ecological sub-model concerning the interactions of impacts on water and biota matrices) is discussed. The sub-model is able to simulate the ecological status of river water bodies by acting on the control of impacts, in particular relating to changes of nutrients and dissolved oxygen. The aim of the present study was threefold. First, to select an appropriate functional form for the model and choose which variables to be included (specification process but without validation). Second, to simulate the responses (and the associated uncertainty) on biological elements due to a hypothesized change of chemical and physical conditions. Third, to provide a user friendly tool, but sufficiently reliable, for the professionals, regional technical structures and Authorities.

Development of a procedure for assessing the environmental risk of the surface water status deterioration

A procedure for estimation of the risk of violation of the water body status was presented. The procedure is based on defining environmental standards of surface water quality taking into account landscape and geographical features of river basins. A database of the systems of monitoring surface water was used to assess the risk of deterioration of the aquatic ecosystem. This enables automated calculation of the environmental risk. At the first stage, it is necessary to determine environmental standards (ES) on the basis of analysis and statistical processing of long-term monitoring data on the qualitative state and hydrological regime taking into account forecasting models. At the second stage, probability of violation of ecological standards is estimated by the ratio of the number of observations of the ecological state of the water body with violation of the ES to the total number of observations. Exceeding environmental standards makes it possible to assess the risk of well-being violation in aquatic ecosystems. Assessment of the environmental risk of deterioration of Udy River and Oskil River in Kharkiv region, Ukraine, has made it possible to make the list of priority pollutants and outline the main problems for which a complex of environmental measures should be worked out. Establishment of the risk of well-being violation in the aquatic ecosystem will contribute to the implementation of a flexible system for regulating water quality taking into account ever-changing socio-economic and environmental conditions. The proposed procedure for assessing the environmental risk of deterioration of the status of aquatic ecosystems is based on the normative basis, approaches and methods of environmental assessment of surface waters adopted in Ukraine and the EU

Valuing the state of water in New Zealand using the experienced preference method

ABSTRACTThis article employs the experienced preference method to value the state of water in New Zealand. In doing so, this article represents a clear contribution to both the literature on non-market valuation and public policy regarding the preservation of water quality. The results show that a one-unit increase in satisfaction with the state of water bodies an individual has visited, is associated with a 1.6 per cent greater likelihood to report being very satisfied with their life. This positive link is robust to the estimation technique employed and a range of control variables. We find the value depends greatly on the functional form imposed on income. Specifically, the use of a cube root functional form yields an implicit willingness-to-pay (WTP) estimate of NZD 11,003, approximately half the size of the base model estimate. Uniquely, we couch this point estimate in the context of a broader distribution of implicit WTP estimates. It is hoped that these results will inform future applications and development of the experienced preference method and support public policy.

Distribution of epiphytic algae on macrophytes of various ecological groups (the case study of water bodies in the Dnieper River basin)

Abstract The generalization and analysis of original data have shown that the nature of epiphytic algae distribution on higher aquatic plants, representing different ecological groups, is very similar in various types of numerous water bodies in the Dnieper River basin. Their species richness and values of quantitative indices were mostly higher on submerged plants compared to plants of other ecological groups. The number of epiphytic algae species was 1.1-1.7 times higher on submerged plants compared to that on half-submerged plants and 1.6-3.1 times higher compared to plants with floating leaves. The taxonomic structure and species composition of epiphyton were very similar on half-submerged and submerged plants and moderately similar on plants with floating leaves compared to macrophytes of other ecological groups. It is emphasized that the specificity of epiphytic algae distribution on macrophytes of various ecological groups should be taken into account when performing monitoring and assessment of the ecological status of water bodies by the bioindication method.

Determination and distribution of region-specific background Secchi depth based on long-term monitoring data in the Seto Inland Sea, Japan

Secchi depth has traditionally been used to assess the light transmittance of a water body and to indicate the degree of eutrophication. Anthropogenic eutrophication can decrease Secchi depth by increasing phytoplankton density. However, Secchi depth is determined not only by phytoplankton density but also by suspended particulate matter, chromophoric dissolved organic matter, and by the optical properties of the seawater itself. These latter factors contribute to a region-specific component of the Secchi depth that is independent of phytoplankton density. The present study aims to estimate this region-specific Secchi depth component, which we term the background Secchi depth (BSD). We compared measured Secchi depth for the past 10 years against BSD to understand the optical condition of extant water bodies and the limits of anthropogenic nutrient reduction as a method of increasing the Secchi depth. Our study analyzed 34 years of seasonal monitoring data across 124 sites in the Seto Inland Sea, Japan. BSD was obtained in 67% and 63% of the sites in the spring and summer, respectively, and 37% and 19% of the sites in autumn and winter. High turbulence during the autumn and winter caused unstable background light attenuation, making it difficult to determine an accurate BSD in many sites. BSD was positively correlated with salinity and water depth and could be estimated from these two parameters. Low BSD was observed near the shore and at shallow sites. Measured Secchi depths over 30% smaller than BSD were observed from 20% to 48% of the sites in 1981–1990, those observations were reduced to 4% to 9% of the sites in the past 10 years (2005–2014), indicating that the impact of eutrophication on light transmittance is not severe at present. Consequently, further reduction of anthropogenic nutrient loads will have a limited effect on Secchi depth in many areas. Moreover, we show the existence of a greater discrepancy between measured Secchi depth and BSD in warm seasons than in cold seasons. Similarly, the difference between measured Secchi depth and BSD was higher in geographically enclosed sub-basins than in other sub-basins.

Characterizing vertical migration of Microcystis aeruginosa and conditions for algal bloom development based on a light‐driven migration model

AbstractLight‐driven vertical migration is critical in dense aggregation of Microcystis aeruginosa during algal blooms under reduced turbulence conditions in natural water bodies. This study examined the vertical migration characteristics of Microcystis aeruginosa in calm water based on a colony migration model with consideration of cell density change, and demonstrated the effects of mucilage fraction, colony size, irradiance intensity, and water turbidity. The results suggest that colonies with larger radii and under higher irradiance usually had a larger daily averaged retention time at the water surface (DRT). In addition to colony size, mucilage was found to be important in changing the vertical migration behavior of Microcystis colonies, in which increasing mucilage volume fraction can increase the migrating velocity of the colony as well as the length of time it remains at the water surface. Increase of light extinction also favors the aggregation of colonies at the surface. An approximate critical value of 2400 µmol photons m2 s−1 for maximum irradiance was found for persistent algal bloom development under the given simulation conditions. Extremely small colonies exposed to irradiance below the critical value were not likely to migrate to the water surface to form algal blooms. According to the DRT values, three regions with different ranges of irradiance and colony size were proposed as the critical conditions for algal bloom development. Rough comparisons to field observations suggested that these results were reasonable and meaningful, and have the potential to be applied in real cases following further validation by more detailed investigations.

Phosphorus sorption-desorption and effects of temperature, pH and salinity on phosphorus sorption in marsh soils from coastal wetlands with different flooding conditions

Wetland soils act as a sink or source of phosphorus (P) to the overlaying water due to phosphorus sorption-desorption processes. Litter information is available on sorption and desorption behaviors of phosphorus in coastal wetlands with different flooding conditions. Laboratory experiments were conducted to investigate phosphorus sorption-desorption processes, fractions of adsorbed phosphorus, and the effects of salinity, pH and temperature on phosphorus sorption on soils in tidal-flooding wetlands (TW), freshwater-flooding wetlands (FW) and seasonal-flooding wetlands (SW) in the Yellow River Delta. Our results showed that the freshly adsorbed phosphorus dominantly exists in Occluded-P and Fe/AlP and their percentages increased with increasing phosphorus adsorbed. Phosphorus sorption isotherms could be better described by the modified Langmuir model than by the modified Freundlich model. A binomial equation could be properly used to describe the effects of salinity, pH, and temperature on phosphorus sorption. Phosphorus sorption generally increased with increasing salinity, pH, and temperature at lower ranges, while decreased in excess of some threshold values. The maximum phosphorus sorption capacity (Qmax) was larger for FW soils (256 mg/kg) compared with TW (218 mg/kg) and SW soils (235 mg/kg) (p < 0.05). The percentage of phosphorus desorption (Pdes) in the FW soils (7.5–63.5%) was much lower than those in TW (27.7–124.9%) and SW soils (19.2–108.5%). The initial soil organic matter, pH and the exchangeable Al, Fe and Cd contents were important factors influencing P sorption and desorption. The findings of this study indicate that freshwater restoration can contribute to controlling the eutrophication status of water bodies through increasing P sorption.

Оценка состояния поверхностных вод с применением многоразовых твердофазных полимерных индикаторов в полевых условиях

As a result of many years of economic activity, a large number of anthropogenic factors arise that change the dynamics of the transformation of the quality of surface waters. The growing deterioration in their quality is due to the long-term impact of various pollution sources (industrial production, road transport, agriculture, technogenic deposits, heat power facilities, oil and gas pipelines, etc.). However, a wide range of heavy metals enters the surface waters, along with the increase in macrocomponents during technogenic dispersion of toxicants. This requires a systemic evaluation of surface water. Modern methods are based on the use of devices that have been used up, recyclable or disposable paper sets with a perceptible range of error in the determination. In this paper, for the rapid analysis of the state of surface waters on the presence of heavy metals, solid-state polymer indicators were used. The possibility of non-laboratory application in practice of color solid-state polymeric indicators of reusable use, preserving shades of color for two years or more, is shown. Characteristics of indicators were studied in laboratory conditions and tested in the study of lake and river water in several Russian regions (Lake Valday, Polomet River, Onego Lake, etc.). The developed methodology is based on the testimony of four parameters: temperature, pH; The changed color of the polymer indicator, followed by a comparison of pH and color with the indicator’s reference scale; Of the total index of water pollution by heavy metals. Comparing the results with the indicators of the working scale, in which all four indicators are included, the estimation of the level of contamination by heavy metals of surface waters with high accuracy is carried out. In addition, this method makes it possible to establish the significant role of bottom sediments in the formation of surface water quality. The results of the carried out research make it possible to increase the number of observations in time and space and to obtain a significant amount of information base on the ecological state of water bodies during their monitoring.

Watershed Urbanization Linked to Differences in Stream Bacterial Community Composition.

Urbanization strongly influences headwater stream chemistry and hydrology, but little is known about how these conditions impact bacterial community composition. We predicted that urbanization would impact bacterial community composition, but that stream water column bacterial communities would be most strongly linked to urbanization at a watershed-scale, as measured by impervious cover, while sediment bacterial communities would correlate with environmental conditions at the scale of stream reaches. To test this hypothesis, we determined bacterial community composition in the water column and sediment of headwater streams located across a gradient of watershed impervious cover using high-throughput 16S rRNA gene amplicon sequencing. Alpha diversity metrics did not show a strong response to catchment urbanization, but beta diversity was significantly related to watershed impervious cover with significant differences also found between water column and sediment samples. Samples grouped primarily according to habitat—water column vs. sediment—with a significant response to watershed impervious cover nested within each habitat type. Compositional shifts for communities in urbanized streams indicated an increase in taxa associated with human activity including bacteria from the genus Polynucleobacter, which is widespread, but has been associated with eutrophic conditions in larger water bodies. Another indicator of communities in urbanized streams was an OTU from the genus Gallionella, which is linked to corrosion of water distribution systems. To identify changes in bacterial community interactions, bacterial co-occurrence networks were generated from urban and forested samples. The urbanized co-occurrence network was much smaller and had fewer co-occurrence events per taxon than forested equivalents, indicating a loss of keystone taxa with urbanization. Our results suggest that urbanization has significant impacts on the community composition of headwater streams, and suggest that processes driving these changes in urbanized water column vs. sediment environments are distinct.

Ecological and geographical characteristics of algal communities on gastropod shells of the river Uzh

Freshwater molluscs serve as test objects in the ecological monitoring of the environment, because they are able to extract in indicator quantity from the environment and accumulate in their bodies radionuclides, various macro- and micronutrients, toxic substances of inorganic and organic origin, and so on. The gastropods are a taxonomically diverse, ecologically plastic and rather widespread group of aquatic organisms, whose role in the life of freshwater ecosystems is very important. Molluscs often have various interactions in biogeocenoses that determines their trophic net. As a rule, these interactions occur in the form of ectocommensalism, endocommensalism, supercrescence, predation or parasitism. The latter type of interaction is the subject of many studies, but the epibionts of gastropods and bivalves have practically not been studied and this research is an effort towards filling this gap. Species composition of algal epibionts identifies specific sensitivity to the effects of certain environmental factors and reflects the processes occurring in their ecosystem water bodies. This determines their efficient use for analyzing changes of water bodies as aquatic habitat, particularly in terms of complex anthropogenic pressure on aquatic ecosystems. The aim of the research was to determine the ecological characteristics of algal communities on gastropod shells: Lymnaea stagnalis, L. auricularia and Viviparus viviparus (the Uzh river, Korosten district, Zhytomyr region). Identified microalgae communities were grouped and studied according to such indices as: confinedness to the habitat (substrate), temperature, fluidity and water oxygenating, saprobiological characteristics according to the Pantle-Buck system in the modification of Sladecek and Watanabe, salinity according to Kolbe’s system, pH at Hustedt scale in the interpretation of M. M. Davydova and geographical limitations of the objects of study. Algal fouling on the shells L. stagnalis, L. auricularia and V. viviparous is formed by benthic and benthic-planktonic species. Algal epibionts of the studied communities are mainly confined to slow-flowing waters. The basis of a floristic list according to the temperature in all studied groups of gastropods is formed by indifferent species. According to geographical distribution of fouling algae, cosmopolitan species dominated. In relation to salinity according to Kolbe’s system, most species discovered were indifferent oligo-galob. Algal communities are reliable indicators of one of the important indices of watercourse hydrochemical conditions – pH of water. Analysis of algal epibionts on gastropod shells of the river Uzh, showed the dominance of alkaliphiles and indifferent species (from the number of identified microalgae). According to saprobiological characteristic of water quality of the river Uzh there was a predominance of o-saprobes. Analysis of indicator groups showed that the most numerous algal epibionts on shells were euresaprobe species. A detailed ecological and geographical characteristic of algae fouling on shells of the studied groups of molluscs allows one to predict the state of hydrocenoses, which is an important aspect of monitoring.Further research is required to model the influence of anthropogenic factors on the state of water bodies.

Percepção ambiental dos moradores das comunidades de Ratones e Lagoa do Peri, Ilha de Santa Catarina

http://dx.doi.org/10.5007/1807-0221.2017v14n25p150A falta de saneamento básico está ligada ao crescimento populacional desconexo de políticas públicas na Ilha de Santa Catarina. Este trabalho, desenvolvido entre julho de 2015 e julho de 2016, teve como objetivo avaliar as percepções de ribeirinhos no município de Florianópolis sobre a situação de corpos d’água nas localidades do Rio Ratones e da Lagoa do Peri. Foram entrevistados 51 moradores no total. Os moradores de Ratones conheciam um maior número de rios da Ilha e relataram abastecimento direto de suas residências por corpos d'água superficiais. Na comunidade da Lagoa do Peri a maioria das residências são abastecidas pela rede pública (CASAN). Ambas as comunidades realizam filtragem intradomiciliar da água, consideram suas matas ciliares degradadas, a chuva importante para os ecossistemas e relataram falta de tratamento de esgoto. Conclui-se que os moradores apresentam uma visão ambiental antropocêntrica.

SPECTRAL RECONSTRUCTION BASED ON SVM FOR CROSS CALIBRATION

Abstract. Chinese HY-1C/1D satellites will use a 5nm/10nm-resolutional visible-near infrared(VNIR) hyperspectral sensor with the solar calibrator to cross-calibrate with other sensors. The hyperspectral radiance data are composed of average radiance in the sensor’s passbands and bear a spectral smoothing effect, a transform from the hyperspectral radiance data to the 1-nm-resolution apparent spectral radiance by spectral reconstruction need to be implemented. In order to solve the problem of noise cumulation and deterioration after several times of iteration by the iterative algorithm, a novel regression method based on SVM is proposed, which can approach arbitrary complex non-linear relationship closely and provide with better generalization capability by learning. In the opinion of system, the relationship between the apparent radiance and equivalent radiance is nonlinear mapping introduced by spectral response function(SRF), SVM transform the low-dimensional non-linear question into high-dimensional linear question though kernel function, obtaining global optimal solution by virtue of quadratic form. The experiment is performed using 6S-simulated spectrums considering the SRF and SNR of the hyperspectral sensor, measured reflectance spectrums of water body and different atmosphere conditions. The contrastive result shows: firstly, the proposed method is with more reconstructed accuracy especially to the high-frequency signal; secondly, while the spectral resolution of the hyperspectral sensor reduces, the proposed method performs better than the iterative method; finally, the root mean square relative error(RMSRE) which is used to evaluate the difference of the reconstructed spectrum and the real spectrum over the whole spectral range is calculated, it decreses by one time at least by proposed method.

Using of GIS technologies and remote sensing tools for monitoring of water objects

An objective assessment of the state of water bodies can be made based on timely and accurate monitoring data. Important requirements of the monitoring is the accuracy of definitions, representativeness, and sufficient repeatability. Relevant monitoring tasks are effective water management, water management, operational and objective assessment of the state of water quality. The tasks is not trivial, however, the use of modern technologies of remote sensing (RS) and Geographic Information Technologies (GIT) allows systematically receive and interpret data photometric parameters of individual water bodies, catchment areas in a wide spectral range with the necessary separation and periodic updating of information, to assess their sanitary - biological characteristics. Modern approaches to the use of remote sensing data to determine the ecological state of water bodies. The issues of practical application of data capture multispectral satellites Landsat-8 for monitoring of water bodies.

Ecological state of water bodies in Middle Ob oil-producing areas

Oil-contaminated zones of small-river watersheds of the Middle Ob region in the areas of the Sovetskoe, Maiskoe, and Festival’noe oilfields of Western Siberia have been investigated. The contamination level was 29–60 g/kg versus 1.8 g/kg for the background. The polluting oil has been found to contain acyclic and aromatic hydrocarbon entities, of which pyrenes, chrysenes, and benzanthracenes are the most toxic. The specific runoff of oil products and their total annual inflow to the river system have been calculated using data of laboratory research, Landsat satellite images, and the software suites ASTER GDEM and SRTM.

Impactos del nitrógeno agrícola en los ecosistemas acuáticos

Eugercios Silva, A.R., Alvarez-Cobelas, M., Montero Gonzalez, E. 2017. Agricultural nitrogen impacts on aquatic ecosystems. Ecosistemas 26(1): 37-44. Doi.: 10.7818/ECOS.2017.26-1.06 Groundwater and surface water bodies have been affected to various stress types since the second half of the twentieth century due to the development of intensive agricultural irrigation activities not only in Spain but also in Europe and globally. Leaching of nitrogen from fertilizers applied to agricultural fields affects the qualitative state of groundwater resources, due to the high nitrate concentrations measured in this water bodies, above the maximum allowable limit. Groundwater acts as a long-term sink for nitrate due to the high transit times and low remediation capacity to mitigate pollution. Nitrogen exportation through the discharge to surface water bodies is the main mechanism of nitrate pollution of rivers, lakes, seas and oceans. High nitrate concentrations cause environmental issues such as the progressive water eutrophication and human health risks (blue baby disease). To achieve good ecological status of water bodies is necessary the comprehensive study of the conceptual model, taking into account the hydric behavior and the source, fate and its transformation processes of the nitrogen cycle.

Open Surface Water Mapping Algorithms: A Comparison of Water-Related Spectral Indices and Sensors

Open surface water bodies play an important role in agricultural and industrial production, and are susceptible to climate change and human activities. Remote sensing data has been increasingly used to map open surface water bodies at local, regional, and global scales. In addition to image statistics-based supervised and unsupervised classifiers, spectral index- and threshold-based approaches have also been widely used. Many water indices have been proposed to identify surface water bodies; however, the differences in performances of these water indices as well as different sensors on water body mapping are not well documented. In this study, we reviewed and compared existing open surface water body mapping approaches based on six widely-used water indices, including the tasseled cap wetness index (TCW), normalized difference water index (NDWI), modified normalized difference water index (mNDWI), sum of near infrared and two shortwave infrared bands (Sum457), automated water extraction index (AWEI), land surface water index (LSWI), as well as three medium resolution sensors (Landsat 7 ETM+, Landsat 8 OLI, and Sentinel-2 MSI). A case region in the Poyang Lake Basin, China, was selected to examine the accuracies of the open surface water body maps from the 27 combinations of different algorithms and sensors. The results showed that generally all the algorithms had reasonably high accuracies with Kappa Coefficients ranging from 0.77 to 0.92. The NDWI-based algorithms performed slightly better than the algorithms based on other water indices in the study area, which could be related to the pure water body dominance in the region, while the sensitivities of water indices could differ for various water body conditions. The resultant maps from Landsat 8 and Sentinel-2 data had higher overall accuracies than those from Landsat 7. Specifically, all three sensors had similar producer accuracies while Landsat 7 based results had a lower user accuracy. This study demonstrates the improved performance in Landsat 8 and Sentinel-2 for open surface water body mapping efforts.

Spatiotemporal changes in the ecological status of water bodies on the mining territories of the Syunik Province (Republic of Armenia)

We discuss the changes in hydrological characteristics of water bodies caused by freshwater withdrawals to meet the interests of various users on the territory of the Syunik Province of the Republic of Armenia. An analysis is made of the possibilities of combining the water withdrawal for mining enterprises and for agriculture. The problems with water supply of settlements located on this territory are highlighted. The temporal dynamics of water withdrawals is presented for separate rivers as well as its relationship with the minimum and ecological flow. It is found that the anthropogenic load on water bodies is more clearly pronounced in the case of a degradation of the quality of water resources as a result of the industrial waste water diversion, and wash-out of pollutants from the territory of enterprises during floods and in the case of emergency input of wastes from tailings pools, rock spoil heaps and waste storage areas. Results of these authors’ observations, data of routine observations and material from published sources were used in analyzing the water quality in the rivers of the Syunik Province. We calculated the coefficients of ecological quality and determined the river water quality classes according to physicochemical and biological indicators. Assessments of the river water quality class were made in accordance with the methodology of Directive 2000/60/EC. We identified the main pollutants that are responsible for the water quality class, and the factors of impact on natural waters governing the ecological status of water bodies. A comprehensive analysis is made of the intensity of anthropogenic impact on surface waters. The ecological status of water bodies is determined. Spatial changes in the quality indicators of the water of the region’s main rivers are demonstrated. Special emphasis is placed on the need to implement immediate measures to improve technological processes and bring the operation of enterprises into compliance with ecological normative standards.