Water Quality Variables Research Articles

Incorporating a new landscape intensity indicator into landscape metrics to better understand controls of water quality and optimal width of riparian buffer zone

River water quality plays a crucial role in numerous industries, necessitating the precise delineation of riparian buffer zones and the implementation of comprehensive management measures to preserve water quality. Determining the optimal riparian buffer zone through the impact of landscape metrics on water quality has been widely applied to river management. However, failure to differentiate the same indicators in areas with different anthropogenic activities could lead to inaccuracies in identifying the optimal riparian buffer zone, particularly in regions with notable gradient in anthropogenic activities. Here, we incorporated a new landscape intensity (NLI) indicator into the landscape metrics to better understand controls of water quality and optimal width of riparian buffer zone, considering the differences between areas with different anthropogenic activities. Based on water quality monitoring data from June 2010 to April 2013 in a typical agricultural-urban gradient with different anthropogenic activities, we adopted redundancy analysis (RDA) to quantify the spatial scale effects and seasonal dependence of various landscape metrics impact on river water quality, and then to reveal the importance of landscape metrics in explaining water quality by variance partitioning analysis (VPA). Results showed that landscape metrics were more effective at explaining the water quality variations during the dry season than the wet season (56.48% ∼ 68.99% vs 53.28% ∼ 58.91%). The 1000 m riparian buffer zone was found to be optimal for explaining water quality changes during the dry season, while the 200 m riparian buffer zone was optimal during the wet season. In addition, we found that NLI was the most important landscape metric in our study and could explain 26% to 52% of the variation in water quality. This study provides a new insight for developing a landscape metric that considers differences in anthropogenic activities, which can help us to better understand water quality changes and preserve aquatic ecosystems.

Formation characteristics of bacteria and fungi in sewers: In terms of signal molecule generation

Bio-metabolism of diverse communities is the main reason of water quality variation in sewers, and the signal molecule generation of communities is dementated to be the key regulation procedure for community metabolism. To reveal the mechanism of pollutant biotransformation in complex sewer environment, this study explored the formation of bacteria and fungi and the signal molecule transduction characteristics in a pilot sewer. In this study, several kinds of signal molecules that produced by bacteria and fungi (C4-HSL, C6-HSL, C8-HSL, farnesol and tyrosol) were detected along the formation process of sewer biofilms. The results showed that, in the early stage, bacterial AHLs signaling molecules are beneficial to the synthesis of EPS, providing a good material basis for the growth of bacterial flora. In addition, tyrosol stimulates the formation of embryonic tubes in yeast cells, further promoting the growth of hyphae. At the later stage, AHLs signaling molecules and tyrosol jointly promoted the growth of biofilms. In conclusion, it is precisely because of the coexistence of bacteria and fungi in the sewer system that the generated signal molecules can jointly promote the synthesis and growth of biofilms through different pathways, and have positive feedback on the biodegradation of various pollutants. Based on the exploration, the ecological patterns of bacterial-fungal communities in urban sewer system were proposed and it could improve the understanding on the pollutant transformation behaviors in sewers.

Assessment of Water Quality Variations and Trophic State of the Joumine Reservoir (Tunisia) by Multivariate Analysis

North Tunisia’s Joumine reservoir provides water for drinking and agriculture irrigation purposes. Therefore, its water quality is crucial, especially with the recurrence of dry years in a global climate change context. This study aims to evaluate its environmental parameters, phytoplankton community structure, and trophic status. The data were newly analyzed using multivariate statistical methods and redundancy analysis (RDA) with the Trophic State Index (TSI) and Trophic State Index deviation (TSID). Monthly sampling occurred from May 2021 to June 2022 at eight stations. Water samples were collected to assess physical-chemical parameters and Chlorophyll-a, as well as to identify phytoplankton species. Three seasonal clusters of summer, autumn, and spring were identified. Water nutrient variations primarily resulted from point and non-point source contamination, along with natural processes. Carlson’s Trophic State Index (CTSI) indicates a eutrophic status for the Joumine reservoir. TSID indicated there was no algal turbidity in the reservoir. The study identified 25 phytoplankton taxa, with Chlorophyceae exhibiting high densities and diversities. RDA revealed that NO3−, NH4+, DO, pH, water flow, and water temperature were the most important environmental factors controlling phytoplankton structure in the Joumine reservoir. The outcomes of this study may provide helpful information to improve the management of the Joumine reservoir.

How far from the shoreline? The effect of catchment land use on the ecological status of flow-through lakes

Catchment land use/land cover (LU/LC) is one of the crucial determinants of the water quality and condition of biota in aquatic environments. The aim of this study was to investigate how LU/LC in lake catchments influences the physicochemical and biological indicators used to assess the ecological status of lakes in Poland and whether these relationships vary depending on the spatial range. We analysed the catchment LU/LC forms of 114 flow-through lakes in three spatial ranges, i.e., a 100 m-wide buffer strip (BUF100), the direct catchment (DIR), and the total catchment (TOT). The water quality and biological variables were derived from the state monitoring conducted in the period 2012–2013. The redundancy analyses (RDA) and the Monte Carlo permutation tests depicted that the strength in explaining the parameter followed the order: TOT > DIR > BUF100 for physicochemical parameters, DIR = TOT > BUF100 for phytoplankton indicators and BUF100 > DIR > TOT for macrophyte indicators. In the direct and total catchment, the proportion of arable lands was decisive in shaping the macrophyte and physicochemical status, while the proportion of artificial surfaces affected phytoplankton status. It was also found that forested buffer zones promoted good macrophyte ecological status. The other types of LU/LC, i.e., meadows and pastures, wetlands, and surface waters exhibited little to no or marginal impact on the physicochemical and biological indicators, regardless of the spatial scale considered. Our results contribute to the rational planning of land development in lake surroundings, including the design of protected areas for inland waters.

Identifying the critical lakeshore zone to optimize landscape factors for improved lake water quality in a semi-arid region of Northeastern China

The degradation of water quality and decline in purification capacity of lakeshore zones due to anthropogenic activities and climate change is a growing concern in China. The identification of the critical width of the lakeshore zone remains a challenge due to natural geographic features and pollutant types, that is why a general identification approach has yet to be developed. To facilitate the planning of lakeshore restoration plans, it becomes necessary to conduct studies focusing on the development of relationships between water quality and landscape factors within the lakeshore zone in different regions. In this study, spatio-temporal patterns of water quality of 49 lakes in Western Jilin Province, China, were determined through field monitoring from 2015 to 2019. Multivariate statistical methods were applied to quantitatively identify the relationships between lakes water quality and landscape factors within lakeshore zones of different widths. The results indicated that nitrogen (N) contributed more to eutrophication, while fluoride concentrations were found to be abnormally high. Furthermore, the width of the lakeshore zone was found to have a significant impact on water quality, with a critical width of 150 m having the greatest effect. Cropland and saline land explained almost 50% of the water quality variability throughout different seasons. The results also revealed that dual control of N and phosphorus (P) will be required to prevent eutrophication in the study area. Agricultural activities and severe soil salinization were identified as the main causes of diffuse pollution. The establishment of a width threshold identification framework for lakeshore zones is not only of great significance for development of scientific and acceptable restoration plans for lakeshore vegetation filters in ecologically vulnerable areas of western Jilin, but should also provide an effective and user-friendly tool for implementing diffuse pollution control.

Spatial responses of water quality to river density and connectivity alterations on the Taihu Plain.

With the advancement of urbanization, the structure and connectivity of river networks have been changed by the interference of human activities, resulting in a series of water environment problems. Numerous studies have indicated that river networks are associated with water quality; unfortunately, few studies have revealed the contributions of the structure and connectivity of river networks to variations in water quality. Taking one water conservancy region with dense and braided rivers on the Taihu Plain as an example, we depicted the spatial aggregations of water quality using the Getis-Ord Gi* index, quantified the variations in polluted regions using the standard deviational ellipse method, and quantified the influence of river density and connectivity on water quality during the different seasons. The results showed that (1) the water quality during the flood season was better than that during the non-flood season, especially in the western region; (2) the spatial aggregations of most water quality indicators were higher and the polluted regions increased in size during the flood period compared to the non-flood period; and (3) the relative contribution rates of the river density and connectivity exhibited mean values of 62.5% (61.2%) and 37.5% (38.8%) in the flood (non-flood) period. Our results provide theoretical support for enhancing water environment management.

Assessment of Spatiotemporal Variations in Water Quality of the Urban River Reach, Yamuna, Delhi

Assessment of Spatiotemporal Variations in Water Quality of the Urban River Reach, Yamuna, Delhi

Microcystin Concentrations and Detection of the mcyA Gene in Water Collected from Agricultural, Urban, and Recreational Areas in a Karst Aquifer in the Yucatan Peninsula of Mexico

The eutrophication of freshwater ecosystems allows the proliferation of cyanobacteria that can produce secondary metabolites such as microcystins. The main aim of this study was to explore the occurrence and concentration of microcystin and the mcyA gene in water bodies located in agricultural, urban, and recreational areas in the karst aquifer of the Yucatan peninsula of Mexico (YPM) and to analyze the water quality variables and chlorophyll-a (Chl-a) associated with their presence. Water samples were collected from 14 sites, and microcystin concentrations were quantified using antibody-based ELISA test. Total DNA was isolated from filters and used for PCR amplification of a fragment of the mcyA gene. Amplicons were cloned and sequenced to identify toxin-producing cyanobacteria present in water. Results showed that water bodies had different trophic status based on Carlson’s trophic state index. Dissolved inorganic nitrogen (DIN: NH4+ + NO3− + NO2−) and P-PO43− concentrations were within a range of 0.077–18.305 mg DIN/L and 0.025–2.5 mg P-PO43−/L, respectively, per sampled site. All sampled sites presented microcystin concentrations within a range of ≥0.14 µg/L to ≥5.0 µg/L, from which 21.4% (3/14) exceeded the limit established in water quality standards for water consumption (1 µg/L). The mcyA gene fragment was detected in 28.5% (4/14) of the sites. A total of 23 sequences were obtained from which 87% (20/23) shared >95% nucleotide identity (nt) with the genus Microcystis and 13% (3/23) shared >87% nt identity with uncultured cyanobacteria. No correlation with the presence of the mcyA gene and microcystins was found; however, a positive correlation was detected between microcystin concentrations with pH and Chl-a.

Applying Biofloc Technology in the Culture of Mugil cephalus in Subtropical Conditions: Effects on Water Quality and Growth Parameters

Mugil cephalus is an estuarine species that has been shown to acclimate to a diversity of environmental conditions being a good candidate to diversify aquaculture. The objective of this study was to evaluate the growth and water quality of M. cephalus juveniles in a biofloc technology system (BFT). Over a period of 87 days, mullet juveniles (117.36 ± 6.48 g) were reared in two experimental conditions: water exchange (control group) (50% three times a week) and BFT (C:N ratio of 15:1). M. cephalus juveniles were stocked at a density of 7.2 kg·m−3. Water quality parameters were monitored periodically. Fish were fed with a balanced artificial feed for marine fish (2% of the total biomass). The water quality parameters were similar between the treatments, with the exception of pH, alkalinity, TSS, and N-NO3 (p < 0.05). Zootechnical parameters WG, DWG, BG, SGR, condition factor, and survival did not show significant differences (p > 0.05). The biomass gain was higher in BFT (p < 0.05). Water quality variables did not appear to influence mullet survival under culture conditions. Mullet is a species that can be reared in BFT without compromising productive performance and having a significant saving of water.

Multi-Dimensional Surface Water Quality Analyses in the Manawatu River Catchment, New Zealand

Land Use and Land Cover (LULC) properties give vital information about pollution signatures in rivers, and they help develop best management practices (BMPs) for effective water resource management. This work employs multivariate statistical methods, receptor modeling, connectivity analysis, and univariate trend analysis to investigate pollution sources across spatiotemporal scales in the Manawatu River, New Zealand. A positive matrix factorization (PMF) method was applied to interpret possible contamination sources. A 25-year dataset (1989–2014) comprising 12 water quality variables from three sites was used. Runoff connectivity analyses identified high-producing grassland (HG) as the most dominant pollution class in all sub-catchments. Univariate analyses revealed that nutrients and sediments were higher than in the initial monitoring years. The PMF analysis found possible pollutants causing impairment, which required attention from waste managers. PMF also showed that point, natural, and agricultural sources significantly contributed to pollution downstream of the river. In the midstream, the erosion, point, and agricultural sources were significant contributing factors. Agricultural pollution and soil erosion were the main contributors to the upstream sub-catchment area. This study suggests that BMPs with a high retention capacity are needed in specific locations in the catchment area to filter high concentrations of pollutants generated.

Assessing water quality in the Pearl River for the last decade based on clustering: Characteristic, evolution and policy implications

The Pearl River (PR) is China's second-largest river, playing a crucial role in regulating and supplying water in the southeast. However, for the last decade, the PR has been experiencing water quality deterioration due to population growth, rapid economic development, and diverse human activities, particularly in its delta areas. This study analyzed the characteristics and evolution of eight water quality variables, including pH values (pH), water temperature (WT), dissolved oxygen (DO), five-day biochemical oxygen demand (BOD5), permanganate index (PI), total phosphorus (TP), ammonia nitrogen (NH3N), and fluoride (F−), which were monitored monthly at 16 water quality monitoring stations from January 2009 to August 2019. Overall, annual average BOD5 and F− concentrations met Class I water quality standards, while TP and NH3N conformed to lower standards. The cluster results showed noticeable differences for parameter grouping (DO-organic parameters-nutrient and solutes), seasonal variation (wet and dry), and water quality status (contaminated-remediating-fine). The Water Quality Index (WQI) ranged from 8.3 ("very poor") to 91.7 ("excellent") in the entire basin from 2009 to 2019, and NH3N-DO based WQImins were identified using the All-Subsets Linear Regression method. The fitting results of the Generalized Additive Models displayed that the deviance explained by natural factors ranged from 37.2% to 61.3%, while the socioeconomic explanation exceeded 70%. The WQImin component evolution (2003–2019) of Shenzhen River estuary, the most important part of the PR estuary, agreed with key parameter variations in heterogeneous clusters in the entire basin. Moreover, Shenzhen's water quality remediation applications indicated that reasonable-efficient-powerful efforts and support from governments could accelerate recovery. For the management departments, consistent measures should be strictly enforced, and elaborate regionalized management based on clusters could be attempted to maintain excellent water quality.

The effect of CO2, total ammonia nitrogen and pH on growth of juvenile lumpfish (Cyclopterus lumpus)

The objective of this study was to examine the effects of CO2, total ammonia nitrogen (TAN: nitrogen bound as either NH3 or NH4+) and pH on the growth and survival of juvenile lumpfish in a two-month growth study. The results demonstrate the complex interactions of these water quality variables. The specific growth rate (SGR) of the lumpfish was progressively reduced with increasing [CO2] concentration above 5–10 mg·L−1. However, growth may be reduced at even lower [CO2] and the results provide no clear safe limits under which the growth of lumpfish is unaffected by CO2 concentration. At the lowest [CO2] tested (8 mg·L−1) the SGR was reduced compared with controls. Moreover, in treatments where the [CO2] concentration increased to 8 mg·L−1 as pH was artificially reduced, the SGR was similarly reduced. These results indicate that lumpfish juveniles are very sensitive to increased [CO2] concentration in water. The SGR of the lumpfish was progressively reduced as the NH4+ concentration increased while maintaining the [NH3] constant (70–80 μg·l−1). However, in these treatments the [CO2] also increased to 8–10 mg·L−1 due to changes in pH and this likely contributed to reduced growth. Moreover, due to nitrification in the rearing systems, the nitrite concentration also increased to critical levels (1.5–4.2 mg·L−1) that could affect growth. Therefore, the results do not provide clear evidence for effects of increased NH4+ on the growth of lumpfish. Taken together, the results of the experiments show that lumpfish are sensitive to perturbations in water quality and provide a benchmark for operational welfare indicators in lumpfish aquaculture.

Remote sensing-based spatiotemporal variation and driving factor assessment of chlorophyll-a concentrations in China’s Pearl River Estuary

Climate change and intensive anthropogenic activities have severely challenged the water quality of China’s Pearl River Estuary (PRE). Further investigations into long-term water quality variation and associated driving mechanisms are therefore necessary to support the sustainable development of the PRE’s Greater Bay Area (GBA). This study used remote sensing retrieval to address long-term spatiotemporal chlorophyll-a (Chl-a) variation characteristics in the PRE and the relationship between Chl-a concentrations and socioeconomic/environmental indicators. Three decades of Landsat satellite images and measured data were collected, and a two-band global algorithm was used to retrieve Chl-a concentration data. Results reveal significant spatiotemporal variability in Chl-a concentrations. The space-averaged Chl-a concentration exhibited a slight downward trend during the past three decades, and the multi-year mean value was 5.20 mg/L. Changes to environmental protection policies in recent years have improved overall PRE water quality. The western section of the PRE had the highest Chl-a concentration (i.e., 5.92 mg/L average) while the eastern section had the lowest (i.e., 3.98 mg/L average). This discrepancy was likely caused by the western section’s more intensive industrial activities, resulting in a higher overall wastewater discharge volume. Affected by climatic conditions, winter Chl-a concentrations were evenly distributed while summer concentrations were significantly higher. Additionally, Chl-a concentrations significantly and positively correlated with total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH3-N), and the biotic oxygen demand (BOD5). Chl-a concentrations also correlated with external factors (i.e., climate and anthropogenic activities). Among these factors, industrial wastewater discharge and the proportion of primary industries in coastal cities significantly and positively correlated with water quality. This study is intended to help direct water quality improvement management and urban sustainable development in the GBA.

Physico-chemical Parameters and Freshwater Fish Diversity of Sip River Madhya Pradesh, India

This study was carried out to analyze the variation in water quality and to investigate the current status of the fish fauna of the Sip river. Water samples and fish specimens were collected on monthly basis from six stations in the months of August 2017- July 2018. All the water quality attributes were found in the acceptable range that supports fish species, except stations IV and V, where pollution load was gradually increases. Seasonal changes in the physico-chemical parameters such as water temperature, pH, DO, free CO2 and total alkalinity revealed the effect on fish species diversity as well as health status of the river. The checklist of fish species recovered during the study was a total of 19 fish species belonging to 9 families, 13 genera and 4 orders. The family Cyprinidae dominant with 11 species, followed by Ambassidae 2 species, while as Bagridae, Channidae, Gobidae, Heteropneustidae, Nandidae and Siluridae each recorded 1 species, respectively. A total of 341 individuals of different fish species were caught from the different stations by using various fishing gears like cast net, gill net, hook and rod methods. Among all the stations studied, the maximum values of abundance 112 and 105 individuals was recorded from V and II stations, followed by I and VI stations having 57 and 51 individuals, while as minimum abundance 7 and 9 individuals was recorded from III and IV stations, respectively. Maximum values of Shannon-Weiner index (2.454) and Simpson’s index (0.906) were recorded from station-V (Pandagaon), while as minimum values of these indices (0.529 and 0.345) were recorded from stations-IV (Syampura). However, maximum values of Margalef’s index (2.793) and Pielou’s index (0.9898) were found from station-II (Ambhakadim) and station-III (Jiryna). The results of the study showed that the Sip river harbors rich ichthyofaunal diversity, but due to some anthropogenic pressure and illegal fishing practices adversely affected the fish diversity. The present study provide base line data initiative to update the current status of fish diversity and water quality parameters and will be useful to enhance the management and conservation strategies, for the fish species of Sip river. Therefore, important steps should be taken into consideration to increase the long-term sustainability of water health and fish activities in the river system

A Simplified Equation for Calculating the Water Quality Index (WQI), Kalu River, Sri Lanka

The water supply system plays a major role in the community. The water source is carefully selected based on quality, quantity, and reliability. The quality of water at its sources is continuously deteriorating due to various anthropogenic activities and is a major concern to public health as well. The Kalu River is one of the major water resources in Sri Lanka that supplies potable water to the Kalutara district (a highly populated area) and Rathnapura district. But, there has been no significant research or investigation to examine anthropogenic activities in the river. Due to this, it is difficult to find any proper study related to the overall water quality in the Kalu River. Therefore, this study covers a crucial part related to the water quality of the Kalu River. The spatiotemporal variation of river water quality is highly important not only to processing any treatment activities but also to implementing policy decisions. In this context, water quality management is a global concern as countries strive to meet the United Nations Sustainable Development Goal 6, which aims to ensure the availability and sustainable management of water and sanitation for all. Poor water quality can have severe consequences on human health, ecosystems, and economies. Contaminated water sources pose risks of waterborne diseases, reduced agricultural productivity, and ecological imbalances. Hence, assessing and improving water quality is crucial for achieving sustainable development worldwide. Therefore, this paper presents a comprehensive analysis of spatiotemporal analysis of the water quality of the Kalu River using the water quality data of eight locations for 6 years from 2017 to 2023. Nine water quality parameters, including the pH, electrical conductivity, temperature, chemical oxygen demand, biological oxygen demand, total nitrate, total phosphate, total sulfate, total chlorine, and hardness, were used to develop a simple equation to investigate the water quality index (WQI) of the river. Higher WQI values were not recorded near the famous Kalutara Bridge throughout the years, even though the area is highly urbanized and toured due to religious importance. Overall, the water quality of the river can be considered acceptable based on the results of the WQI. The country lockdowns due to COVID-19 might have impacted the results in 2020; this can be clearly seen with the variation of the annual WQI average, as it clearly indicates decreased levels of the WQI in the years 2020 and 2021, and again, the rise of the WQI level in 2022, as this time period corresponds to the lockdown season and relaxation of the lockdown season in the country. Somehow, for most cases in the Kalu River, the WQI level is well below 25, which can be considered acceptable and suitable for human purposes. But, it may need some attention towards the areas to find possible reasons that are not in the range. Nevertheless, the results suggest the importance of continuous water quality monitoring in the Kalu River.

Assessment of Temporal Variation of Water Quality Parameters and Ecotoxic Trace Metals in Southern Nigeria Coastal Water

Assessment of Temporal Variation of Water Quality Parameters and Ecotoxic Trace Metals in Southern Nigeria Coastal Water

Agricultural land use and morphometry explain substantial variation in nutrient and ion concentrations in lakes across Canada

Declines in freshwater quality resulting from anthropogenic nutrient input remain a persistent issue worldwide. Yet, we still have a limited understanding of the magnitude and scale at which most lakes have been affected by human activities, namely Land Use/Land Cover (LULC) alterations. In response, the NSERC Canadian Lake Pulse Network has compiled the first nationwide systematic database of lake quality metrics by surveying 664 lakes across 12 ecozones over 3 years. To assess the influence of catchment development on water quality and its spatial variation, we built generally additive models and multivariate regressions to quantify the association between watershed LULC and lake temperature, Secchi depth, as well as chlorophyll- a, limiting nutrient, and ion concentrations. We found that agricultural and urban land use explained the greatest proportion of variation in water quality among LULC categories ( R2 = 0.20–0.29). Overall, our study highlights that drivers of water quality are similar across regions; however, baseline conditions vary, so freshwater ecosystem management strategies must consider their geographic context to better predict where water quality thresholds will be surpassed.

Hybrid model for daily streamflow and phosphorus load prediction.

Environmental factors, such as climate change and land use changes, affect water quality drastically. To consider these, various predictive models, both process-based and data-driven, have been used. However, each model has distinct limitations. In this study, a hybrid model combining the soil and water assessment tool and the reverse time attention mechanism (SWAT-RETAIN) was proposed for predicting daily streamflow and total phosphorus (TP) load of a watershed. SWAT-RETAIN was applied to Hwangryong River, South Korea. The hybrid model uses the SWAT output as input data for the RETAIN. Spatial, meteorological, and hydrological data were collected to develop the SWAT to generate high temporal resolution data. RETAIN facilitated effective simultaneous prediction. The SWAT-RETAIN exhibited high accuracy in predicting streamflow (Nash-Sutcliffe efficiency (NSE): 0.45, root mean square error (RMSE): 27.74, percent bias (PBIAS): 22.63 for test sets), and TP load (NSE: 0.50, RMSE: 423.93, PBIAS: 22.09 for test sets). This result was evident in the performance evaluation using flow duration and load duration curves. The SWAT-RETAIN provides enhanced temporal resolution and performance, enabling the simultaneous prediction of multiple variables. It can be applied to predict various water quality variables in larger watersheds.

The impacts of human-induced disturbances on spatial and temporal stream water quality variations in mountainous terrain: A case study of Borcka Dam Watershed

Unaltered watersheds with natural vegetation cover (forest, grasslands, etc.) provide several ecological benefits in addition to providing freshwater, controlling water levels, and supporting flourishing streamside ecosystems. However, as in many watersheds in the World, the research area in this study, the Borcka Dam Watershed (BDW), has been affected by many human-induced disturbances affecting a wide area of forest and grassland areas as well as soil and water resources. Therefore, the objective of this study was to assess and evaluate the possible effects of anthropogenic disturbances, particularly on annual changes in water discharge, some water quality parameters, and total suspended sediment (TSS) amounts in the main streams of four sub-watersheds (Fabrika, Godrahav, Hatila, and Murgul) and the reservoir of the dam. In addition, we intend to confirm that land use change and/or transformation play a significant role in influencing stream water quality. The YSI/Professional-Plus, a portable water quality measurement device, was used to determine the amounts of pH, dissolved oxygen (DO), total dissolved substance (TDS), ammonium (NH4–N), nitrate (NO3–N), salinity, electrical conductivity (EC), and temperature besides measuring discharge and total suspended sediments (TSS) from a total of 27 sampling points in the field. Although the results revealed that the annual mean values of all water quality parameters for all four streams were mostly in good condition, for some time and points of the measurements, several parameters were found to be above the official water quality standards due to the intensive aforementioned anthropogenic activities, particularly in the stream waters of Murgul (e.g. pH and TSS being 10,84 and 236 mg/L, respectively) and Fabrika (e.g. EC of 412 μs/cm; DO of 4.44 mg/L; 14 ml of NO3–N) sub-watersheds. These outcomes indicate that these two sub-watersheds have been impacted more severely by the human-induced disturbances compared to Hatila and Godrahav sub-watersheds.

Trophic state and potential productivity assessment for Qaroun Lake using spatial techniques

Qaroun Lake is one of the most important Egyptian lakes which, recently, have been exposed to severe degradation in water quality and fish productivity. In this manuscript, Carlson’s trophic state index (CTSI) was used to evaluate the trophic state, while the trophometric index (TMI) was used to assess the potential productivity of Qaroun Lake. The present study is one of the initial attempts to investigate these indices in Qaroun Lake. To achieve this work, an integrated multidisciplinary approach was adopted integrating field investigation, geographic information system, and data analysis. CTSI combines three variables of water quality: chlorophyll-a (CHL-a), total phosphorus (TP), and transparency measured by Secchi disk depth (SDD). The result of overall CTSI showed the hypereutrophic state is represented by 62% and eutrophic state is represented by 38% of the total lake’s area. Moreover, the calculated TMI indicated the average potential productivity value (PP) is 619 t. It can be concluded that the hypereutrophic is the dominant state in Qaroun Lake. The present study recommends the application of TMI model to evaluate and monitor the changes in Qaroun Lake’s potential productivity in response to the changing environmental conditions and other biological pressures (e.g., Isopoda paraside).