Estimation and Assessment of Total Phosphorus and Trophic State Index Estimated from Landsat 8 Dataset on 2018 at Daecheong Reservoir

Objectives : Remote sensing of water quality parameters (WQPs) has been widely applied along with the emerging importance of obtaining the spatial pattern of water quality at inland reservoir. This study retrieved the Total Phosphorus (TP) via remote sensing imagery at Daecheong reservoir and used it for acquiring the spatial distribution of Trophic State Index (TSI).Methods : First, stepwise regression for TP was established using the ground-based TP measurement and reflectance of Landsat 8 collocated in space and time. With the developed regression model, we estimated the spatial distribution of TSI and evaluated the severity of eutrophication at Daecheong reservoir.Results and Discussion : The result confirmed that predicted TP yielded reasonable statistics compared against measured TP with R2 of 0.956 and p-value of 0.022. Seasonal variation of TP was highly influenced by the precipitation. Similarly, precipitation also influenced to the spatial pattern of TSI. Before the rainfall event (e.g., August 22 2018) at Daecheong reservoir, TSI metric indicated the oligotrographic stage. However, TSI of Daecheong reservoir after the rainfall (e.g., October 25 2018) indicated the mesotrophic and eutrophic stage.Conclusions : These results confirmed that the retrieval of WQP from remote sensing imagery can serve as a robustness tool to monitor the water quality over the large scale area.

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APLIKASI CITRA LANDSAT 8 OLI UNTUK IDENTIFIKASI STATUS TROFIK WADUK GAJAH MUNGKUR WONOGIRI, JAWA TENGAH

MAJALAH ILMIAH GLOBE ◽

10.24895/mig.2017.19-2.633 ◽

2017 ◽

Vol 19 (2) ◽

pp. 113

Author(s):

Kusuma Wardani Laksitaningrum ◽

Wirastuti Widyatmanti

Keyword(s):

Chlorophyll A ◽

Total Phosphorus ◽

Trophic State ◽

Water Clarity ◽

Coefficient Of Determination ◽

Physical Factors ◽

Landsat 8 ◽

Trophic State Index ◽

Landsat 8 Oli ◽

State Index

ABSTRAKWaduk Gajah Mungkur (WGM) adalah bendungan buatan yang memiliki luas genangan maksimum 8800 ha, terletak di Desa Pokoh Kidul, Kecamatan Wonogiri, Kabupaten Wonogiri. Kondisi perairan WGM dipengaruhi oleh faktor klimatologis, fisik, dan aktivitas manusia yang dapat menyumbang nutrisi sehingga mempengaruhi status trofiknya. Tujuan dari penelitian ini adalah mengkaji kemampuan citra Landsat 8 OLI untuk memperoleh parameter-parameter yang digunakan untuk menilai status trofik, menentukan dan memetakan status trofik yang diperoleh dari citra Landsat 8 OLI, dan mengevaluasi hasil pemetaan dan manfaat citra penginderaan jauh untuk identifikasi status trofik WGM. Identifikasi status trofik dilakukan berdasarkan metode Trophic State Index (TSI) Carlson (1997) menggunakan tiga parameter yaitu kejernihan air, total fosfor, dan klorofil-a. Model yang diperoleh berdasar pada rumus empiris dari hasil uji regresi antara pengukuran di lapangan dan nilai piksel di citra Landsat 8 OLI. Model dipilih berdasarkan nilai koefisien determinasi (R2) tertinggi. Hasil penelitian merepresentasikan bahwa nilai R2 kejernihan air sebesar 0,813, total fosfor sebesar 0,268, dan klorofil-a sebesar 0,584. Apabila nilai R2 mendekati 1, maka semakin baik model regresi dapat menjelaskan suatu parameter status trofik. Berdasarkan hasil kalkulasi diperoleh distribusi yang terdiri dari kelas eutrofik ringan, eutrofik sedang, dan eutrofik berat yaitu pada rentang nilai indeks 50,051 – 80,180. Distribusi terbesar adalah eutrofik sedang. Hal tersebut menunjukkan tingkat kesuburan perairan yang tinggi dan dapat membahayakan makhluk hidup lain.Kata kunci: Waduk Gajah Mungkur, citra Landsat 8 OLI, regresi, TSI, status trofikABSTRACTGajah Mungkur Reservoir is an artificial dam that has a maximum inundated areas of 8800 ha, located in Pokoh Kidul Village, Wonogiri Regency. The reservoir’s water conditions are affected by climatological and physical factors, as well as human activities that can contribute to nutrients that affect its trophic state. This study aimed to assess the Landsat 8 OLI capabilities to obtain parameters that are used to determine its trophic state, identifying and mapping the trophic state based on parameters derived from Landsat 8 OLI, and evaluating the results of the mapping and the benefits of remote sensing imagery for identification of its trophic state. Identification of trophic state is based on Trophic State Index (TSI) Carlson (1997), which uses three parameters there are water clarity, total phosphorus, and chlorophyll-a. The model is based on an empirical formula of regression between measurements in the field and the pixel values in Landsat 8 OLI. Model is selected on the highest value towards coefficient of determination (R2). The results represented that R2 of water clarity is 0.813, total phosphorus is 0.268, and chlorophyll-a is 0.584. If R2 close to 1, regression model will describe the parameters of the trophic state better. Based on the calculation the distribution consists of mild eutrophic, moderate eutrophic, and heavy eutrophic that has index values from 50.051 to 80.18. The most distribution is moderate eutrophication, and it showed the high level of trophic state and may harm other living beings.Keywords: Gajah Mungkur Reservoir, Landsat 8 OLI satellite imagery, regression, TSI, trophic state

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Assessment of Trophic Responses of a Reservoir to Seasonal and Annual Variations in Monsoon

Water ◽

10.3390/w13152117 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2117

Author(s):

Su-mi Kim ◽

Hyun-su Kim

Keyword(s):

Water Quality ◽

Trophic State ◽

Monsoon Season ◽

Phytoplankton Growth ◽

Phosphorus Loading ◽

Nutrient Concentrations ◽

Trophic State Index ◽

Post Monsoon ◽

Post Monsoon Season ◽

State Index

The variations in water quality parameters and trophic status of a multipurpose reservoir in response to changing intensity of monsoon rain was investigated by applying a trophic state index deviation (TSID) analysis and an empirical regression model to the data collected in two periods from 2014 to 2017. The reservoir in general maintained mesotrophic conditions, and Carlson’s trophic state index (TSIc) was affected most by TSITP. Nutrient concentrations, particularly phosphorus, did not show strong correlations with precipitation, particularly in the period with weak monsoon, and a significant increase in total phosphorus (TP) was observed in Spring 2015, indicating the possibility of internal phosphorus loading under decreased depth and stability of water body due to a lack of precipitation. TSIChl was higher than TSISD in most data in period 1 when a negligible increase in precipitation was observed in the monsoon season while a significant fraction in period 2 showed the opposite trend. Phytoplankton growth was not limited by nutrient limitation although nutrient ratios (N/P) of most samples were significantly higher than 20, indicating phosphorus-limited condition. TSID and regression analysis indicated that phytoplankton growth was limited by zooplankton grazing in the Spring, and that cell concentrations and community structure in the monsoon and post-monsoon season were controlled by the changing intensity of the monsoon, as evidenced by the positive and negative relationships between community size and cyanobacterial population with the amount of precipitation in the Summer, respectively. The possibility of contribution from internal loading and an increase in cyanobacterial population associated with weak monsoon, in addition to potential for nutrient enrichment in the post-monsoon season, implies a need for the application of more stringent water quality management in the reservoir that can handle all potential scenarios of eutrophication.

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Remote Estimation of Trophic State Index for Inland Waters Using Landsat-8 OLI Imagery

Remote Sensing ◽

10.3390/rs13101988 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1988

Author(s):

Minqi Hu ◽

Ronghua Ma ◽

Zhigang Cao ◽

Junfeng Xiong ◽

Kun Xue

Keyword(s):

Yangtze River ◽

Trophic State ◽

Inland Waters ◽

Landsat 8 ◽

Trophic State Index ◽

Type I ◽

Water Type ◽

Type Ii ◽

Turbid Water ◽

State Index

Remote monitoring of trophic state for inland waters is a hotspot of water quality studies worldwide. However, the complex optical properties of inland waters limit the potential of algorithms. This research aims to develop an algorithm to estimate the trophic state in inland waters. First, the turbid water index was applied for the determination of optical water types on each pixel, and water bodies are divided into two categories: algae-dominated water (Type I) and turbid water (Type II). The algal biomass index (ABI) was then established based on water classification to derive the trophic state index (TSI) proposed by Carlson (1977). The results showed a considerable precision in Type I water (R2 = 0.62, N = 282) and Type II water (R2 = 0.57, N = 132). The ABI-derived TSI outperformed several band-ratio algorithms and a machine learning method (RMSE = 4.08, MRE = 5.46%, MAE = 3.14, NSE = 0.64). Such a model was employed to generate the trophic state index of 146 lakes (> 10 km2) in eastern China from 2013 to 2020 using Landsat-8 surface reflectance data. The number of hypertrophic and oligotrophic lakes decreased from 45.89% to 21.92% and 4.11% to 1.37%, respectively, while the number of mesotrophic and eutrophic lakes increased from 12.33% to 23.97% and 37.67% to 52.74%. The annual mean TSI for the lakes in the lower reaches of the Yangtze River basin was higher than that in the middle reaches of the Yangtze River and Huai River basin. The retrieval algorithm illustrated the applicability to other sensors with an overall accuracy of 83.27% for moderate-resolution imaging spectroradiometer (MODIS) and 82.92% for Sentinel-3 OLCI sensor, demonstrating the potential for high-frequency observation and large-scale simulation capability. Our study can provide an effective trophic state assessment and support inland water management.

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KAJIAN KUALITAS PERAIRAN UNTUK PERIKANAN DI RAWA PENING JAWA TENGAH

BAWAL Widya Riset Perikanan Tangkap ◽

10.15578/bawal.8.3.2016.173-182 ◽

2017 ◽

Vol 8 (3) ◽

pp. 173

Author(s):

Siti Nurul Aida ◽

Agus Djoko Utomo

Keyword(s):

Water Pollution ◽

Water Quality ◽

Trophic Level ◽

Carrying Capacity ◽

Water Hyacinth ◽

Trophic State ◽

Fish Growth ◽

Household Waste ◽

Trophic State Index ◽

State Index

Perairan Rawa Peningmerupakan tipe perairan yang tergenang dan mempunyai arti penting bagi perikanan. Masalah utama yang ada di Rawa Pening yaitu pendangkalan karena sedimentasi dan eutrofikasi yang disebabkan pencemaran air berasal dari limbah rumah tangga, pertanian dan budidaya perikanan. Penelitian ini bertujuan untukmengetahui tingkat kesuburan perairan dan kualitas air di Rawa Pening. Penelitian dilakukan pada bulan Mei, Juni, Agustus dan Oktober 2013. Frekuensi pengambilan contoh dilakukan empat kali yaitu pada bulan Mei, Juni,Agustus dan Oktober. Stasiun pengamatan meliputi:A. Tengah (Puteran); B.Muara sungai (Torong); C.Area KJA; D. Pemotongan eceng Gondok (tengah 1); E. Sungai keluar (Tuntang); F. Muara sungai (Muncul); G. Tidak ada pemotongan eceng gondok (tengah 2). Data tingkat kesuburan perairan dianalisis dengan metode Carlon’s.Hasil penelitianmenunjukkan bahwa Rawa Pening termasuk katagori perairan dengan tingkat kesuburan tinggi, nilai Thropic State Index (TSI) pada semua stasiun pengamatan berkisar antara 57,22 - 68,06. Kondisi kualitas air yang kurang baik tersebut akanmerugikan perikanan, seperti kejadian kematian ikanmasal, lambatnya pertumbuhan ikan dan penurunan daya dukung perairan.The Rawa Pening waters is a lentic water and has significance for fishery. The main problems in Rawa Pening are silting due to sedimentation and eutrophication due to water pollution from household waste, agriculture and fisheries. The study aims to examine trophic level and water quality. The research conducted on May, June, August and October 2013. There was 7 stations i.e. A. middle (Puteran); B. inlet of Torong; C. Location of aquaculture;D. locations where harvesting of water hyacinth occurred (middle1); E. outlet (Tuntang); F. inlet (Muncul); G. location where no harvest of water hyacinth (middle 2). Trophic level were analyzed by Carlon’s method. The results showed that Rawa Pening waters categorized as the high eutrophication level where the Trophic State Index (TSI) was 57. 22 to 68. 06. The low water quality will be detrimentaled to fisheries, such as mass fish death, slow fish growth and also a decline of carrying capacity of ecosystem.

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Trophic Status and Phytoplankton Limitation Conditions in a Few Bulgarian and Hungarian Danube River Wetlands

Transylvanian Review of Systematical and Ecological Research ◽

10.1515/trser-2015-0084 ◽

2016 ◽

Vol 18 (2) ◽

pp. 19-28

Author(s):

Roumen Kalchev ◽

Árpád Berczik ◽

Michaela Beshkova ◽

Mária Dinka ◽

Hristina Kalcheva ◽

...

Keyword(s):

Chlorophyll A ◽

Total Nitrogen ◽

Total Phosphorus ◽

Trophic State ◽

Trophic Status ◽

Danube River ◽

Trophic State Index ◽

Secchi Disk ◽

State Index

Abstract The phytoplankton limitation conditions in a few Bulgarian and Hungarian wetlands and in two more sampling sites, one for each Danube stretch, were investigated by means of trophic state index of Carlson (1977) for phytoplankton chlorophyll-a (CHL), Secchi disk depths (SD), total phosphorus (TP), and total nitrogen (TN) concentrations. Phytoplankton of both river sites was not limited by non-algal turbidity, nor was they phosphorus and nitrogen limited. In summer months the studied wetlands were predominantly nitrogen limited, while in spring and autumn limitation by non-algal turbidity prevailed.

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Were there any changes in zooplankton communities due to the limitation of restoration treatments?

Limnological Review ◽

10.2478/limre-2021-0009 ◽

2021 ◽

Vol 21 (2) ◽

pp. 91-104

Author(s):

Joanna Rosińska ◽

Katarzyna Kowalczewska-Madura ◽

Anna Kozak ◽

Wanda Romanowicz-Brzozowska ◽

Ryszard Goldyn

Keyword(s):

Water Quality ◽

Species Composition ◽

Trophic State ◽

Species Number ◽

Trophic State Index ◽

Keratella Cochlearis ◽

Bottom Waters ◽

Phosphorus Inactivation ◽

State Index ◽

Zooplankton Communities

Abstract Zooplankton is a good indicator of water quality state. Analysing the species composition and abundance, it is possible to assess the condition of the water body and predict the direction of changes. The aim of the study was to analyse the zooplankton in a shallow urban lake, in which restoration was limited to one method, i.e. wind-aeration. The results were compared with the earlier data obtained during sustainable restoration (three methods: wind-aeration, phosphorus inactivation, biomanipulation) and before the restoration period. The zooplankton was sampled monthly in 2015 and 2016 in the deepest place of the lake from the surface to the bottom. The trophic state was determined based on rotifer trophic state index for lakes (TSIROT). Although the species composition of zooplankton communities varied very little among the restoration periods (Keratella cochlearis f. tecta mainly dominated), significant changes in the abundance of zooplankton were found in the analysed lake. The maximum of total abundance was noted in 2015, almost 5500 ind. L−1, and in the next year its decrease was almost 3-fold, to ca. 1800 ind. L-1. Based on TSIROT, the water was still eutrophic. Leaving only one method of restoration (namely, oxygenation of the bottom waters) proved insufficient to support the development of crucial organisms as cladocerans. The changes in the abundance could have resulted more from seasonal changes than from the effects of aeration. A reduction in species number and maintaining a high proportion of rotifers typical for a high trophic state indicated a return of the ecosystem to its pre-restoration state. High variability in the rotifer abundance indicated a continuous imbalance of the ecosystem. Previous restoration treatments using several methods simultaneously showed better effectiveness. The change of strategy of restoration before obtaining a stable improvement of water quality destroyed previously achieved effects.

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A INTERFERÊNCIA DAS ATIVIDADES ANTRÓPICAS NA QUALIDADE DA ÁGUA EM RESERVATÓRIO DE ABASTECIMENTO URBANO. ESTUDO DE CASO: REPRESA DR. JOÃO PENIDO (JUIZ DE FORA, MG)

Eclética Química Journal ◽

10.26850/1678-4618eqj.v37.1.2012.p09-22 ◽

2017 ◽

Vol 37 (1) ◽

pp. 09

Author(s):

Maria Magaly Heidenreich Silva Bucci ◽

Luiz Fernando Cappa de Oliveira

Keyword(s):

Water Quality ◽

Land Use ◽

Quality Index ◽

Anthropogenic Impact ◽

Trophic State ◽

Trophic State Index ◽

Monitoring Tool ◽

State Index ◽

Negative Impacts

Dr. João Penido dam is the main reservoir for water supply of Juiz de Fora (MG). The forms of land use and occupation have produced negative impacts on the aquatic ecosystem. The general objective of this study was to assess the anthropogenic impact on water quality of the watershed. To this was done to characterize the quality of its waters and the parameters measured were compared with CONAMA Resolution 357/2005. It was also calculated the Water Quality Index (WQI) and the Trophic State Index (TSI). The monitoring tool has proved essential in actions involving preservation of the watershed.

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Study of the Water Quality of a Tropical Reservoir

10.20944/preprints201812.0335.v1 ◽

2018 ◽

Author(s):

Alberto Quevedo-Castro ◽

Jesús L. López ◽

Jesus Gabriel Rangel-Peraza ◽

Erick Bandala ◽

Yaneth Bustos-Terrones

Keyword(s):

Water Quality ◽

Ecological Risk ◽

Trophic State ◽

Risk Index ◽

Trophic State Index ◽

Tropical Reservoir ◽

State Index ◽

Using Data

A study of the water quality of the Adolfo López Mateos Reservoir (ALMD) was developed through different indicators from a spatial and seasonal perspective. Variables related to the general characteristics of water quality, trophic level and ecological risk were assessed through the water Quality Index (WQINSF-BROWN), Trophic State Index (TSICARLSON) and the Ecological Risk Index (RIHAKANSON). Using data from physical, chemical and biological parameters obtained from four sampling points in the ALMD, the water quality was assessed in each model used. The results indicated that the reservoir presents a water quality classified as “medium” (WQINSF-BROWN = 70), where significant variations in the concentrations of some parameters are observed. The reservoir showed a general trophic state classified as “Mesotrophic” (TSIGENERAL-AVERAGE = 43.04). The ecological risk analysis achieved the best classification of the methodology, discarding contamination by heavy metals in surface waters. Through this type of applied methodologies will help as decision making tools in the dam, as well as for application in other dams in the region.

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Assessment of Temporal Variation of Water Quality Parameters and the Trophic State Index in a Subtropical Water Reservoir of Bangladesh

Grassroots Journal of Natural Resources ◽

10.33002/nr2581.6853.040313 ◽

2021 ◽

Vol 4 (3) ◽

pp. 164-184

Author(s):

Md. Sirajul Islam ◽

Yousuf Ali ◽

Md. Humayun Kabir ◽

Rofi Md. Zubaer ◽

Nowara Tamanna Meghla ◽

...

Keyword(s):

Water Quality ◽

Chlorophyll A ◽

Trophic State ◽

Monsoon Season ◽

Water Reservoir ◽

Quality Parameters ◽

Total Alkalinity ◽

Total Hardness ◽

Trophic State Index ◽

State Index

This study was conducted to determine the suitability of water quality for fisheries management in Kaptai Lake from February 2019 to January 2020. Results showed that the temperature, transparency, TDS, pH, DO, EC, alkalinity and hardness were 20.9 to 31.8°C, 17 to 303 cm, 40 to 105 mg/L, 6.82 to 7.96, 6.1 to 7.65 mg/L, 75.33 to 172.33 µS/cm, 37 to 83 mg/L and 35 to 190 mg/L, respectively. However, nutrients as NH3, NO3-, NO2-, PO43- and SO42- were 0.01 to 0.05, 0.03 to 2.21, 36 to 96, 0.01 to 0.04 and 0.3 to 1.9 mg/L, respectively. Chlorophyll a and trophic state index (TSI) were 0.70 to 2.12 µg/L and 27.43 to 37.79, respectively. Study revealed that SO42-, DO and TDS were higher than the standard of ECR. On the other hand, NH3, NO3-, NO2-, PO43-, temperature, transparency, pH, EC, total hardness, total alkalinity, Chlorophyll a and TSI were within the standard levels. Concentrations of NO3-, NO2-, PO43-, Chlorophyll a and TSI (CHL) showed no significant variation with seasons. Conversely, TDS, transparency, EC, alkalinity, hardness, and SO42- were lower in monsoon compared to pre-monsoon and post-monsoon seasons. Besides, temperature, NH3, DO and TSI (SD) were higher in monsoon season. Results concluded that the Kaptai Lake is in mesotrophic condition with TSI (CHL) less than 40, and prominently there was a positive relationship between Chlorophyll a and Trophic State Index (TSI). In this regard, major nutrients and Chlorophyll a concentration in the Kaptai Lake may have an impact on the aquatic environment.

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DETERMINAÇÃO E AVALIAÇÃO DO ÍNDICE DE ESTADO TRÓFICO (IET) EM RIO URBANO LOCALIZADO NO ESTADO DO CEARÁ, BRASIL

Revista da Casa da Geografia de Sobral (RCGS) ◽

10.35701/rcgs.v21n2.487 ◽

2019 ◽

Vol 21 (2) ◽

pp. 730-744

Author(s):

Francisco Bruno Monte Gomes ◽

Davis Pereira De Paula

Keyword(s):

Chlorophyll A ◽

Total Phosphorus ◽

Urban Space ◽

Trophic State ◽

Trophic State Index ◽

Sampling Point ◽

Water Sampling ◽

State Index ◽

High Concentrations ◽

Del Rio

A pesquisa teve como objetivo analisar o índice de estado trófico no rio Acaraú localizado em Sobral-Ceará-Brasil. A metodologia consistiu em revisões bibliográficas, análises de campo, delimitação de cinco pontos amostrais ao longo do trecho fluvial, culminando na coleta de amostras de água e avaliação dos parâmetros de Clorofila “A” e Fósforo Total, no período de março/2015 a março/2016. O trecho do rio Acaraú no espaço urbano de Sobral foi dividido em cinco trechos principais, abrangendo entrada e saída. A Clorofila “A” apresentou uma crescente nas estações PT-3 (40,0 µg/L), PT-4 (32,0 µg/L), nos meses de setembro/15 e PT-5 (12,5 µg/L), para o mês de março/16, os menores resultados foram nas estações PT-1 (6,2 µg/L a 9,0 µg/L), PT-2 (6,7 µg/L a 8,0 µg/L). O Fósforo Total variou entre 0,02 mg/l em agosto/15 na estação PT-1 a 22,5 mg/l em dezembro/15 da estação de coleta PT-5. O cálculo do IET (Índice de Estado Trófico) se mostrou com nível de predominância no grau mesotrófico nos pontos PT-1, PT-3 e PT-5, entre agosto/15 a dezembro/15. O grau hipereutrófico foi resultado nos pontos PT-3, PT-4 e PT-5, afetados significativamente pelas elevadas concentrações de matéria orgânica e nutrientes. Portanto, conclui-se que as águas no rio Acaraú apresentaram vulnerabilidades aos processos de eutrofização, se fazendo necessária a implantação de um planejamento urbano eficiente.Palavras-chave: Eutrofização; Poluição hídrica; Qualidade de água; Rio urbano. ABSTRACTThe aim of this research was analyze the trophic state index in the Acaraú river located in Sobral-Ceará-Brazil. The methodology consisted of bibliographic reviews, field recognition, delimitation of five sampling points along the river, culminating in the water sampling and evaluation of the parameters of Chlorophyll "A" and Total Phosphorus, from March/2015 to March/2016. The section of the Acaraú River in the urban space of Sobral was divided into five main sections, including entrance and exit. Chlorophyll "A" increased in PT-3 (40.0 μg/L), PT-4 (32.0 μg/L) in September/15 and PT-5 (12.5 μg/L), for the month of March/16, the lowest results were in PT-1 (6.2 μg/L at 9.0 μg/L), PT-2 (6.7 μg/L at 8.0 μg/L). Total Phosphorus ranged from 0.02 mg/L to 22.5 mg/L (August/15– December/15) at the PT-5 sampling point. The TSI (Trophic State Index) showed that there was predominance on mesotrophic degree at points PT-1, PT-3 and PT-5among August/15 and December/15. The hypereutrophic degree that was found in points PT-3, PT-4 and PT-5, were the results of a significant influence by high concentrations of organic matter and nutrients. Therefore, it is concluded that the waters in Acaraú River presents vulnerabilities to the eutrophication processes, and it is necessary to implement efficient urban planning.Keywords: Eutrophication; Water pollution; Water quality; Urban river. RESUMENLa investigación tuvo como objetivo analizar el índice de estado trófico en el río Acaraú ubicado en Sobral-Ceará-Brasil. La metodología consistió en revisiones bibliográficas, análisis de campo, delimitación de cinco puntos de muestreo a lo largo de la sección del río, que culminó con la recolección de muestras de agua y la evaluación de los parámetros de Clorofila "A" y Fósforo Total, de marzo/2015 a marzo/2016. El tramo del río Acaraú en el espacio urbano de Sobral se dividió en cinco tramos principales, que incluyen la entrada y la salida. La clorofila “A” presentó un crecimiento en las estaciones PT-3 (40.0 µg/L), PT-4 (32.0 µg/L) en septiembre/15 y PT-5 (12.5 µg/L). L), para el mes de marzo/16, los resultados más bajos fueron en PT-1 (6.2 µg/L a 9.0 µg/L), PT-2 (6.7 µg/L a 8.0 µg/L). El fósforo total varió de 0.02 mg/l en agosto/15 en la estación PT-1 a 22.5 mg/l en diciembre/15 desde la estación de recolección PT-5. El cálculo del EIT (Índice de estado trófico) fue predominantemente mesotrófico en PT-1, PT-3 y PT-5, del 15 de agosto al 15 de diciembre. El grado hipereutrófico se obtuvo en los puntos PT-3, PT-4 y PT-5, significativamente afectados por las altas concentraciones de materia orgánica y nutrientes. Por lo tanto, se concluye que las aguas del río Acaraú presentan vulnerabilidades a los procesos de eutrofización, lo que hace necesaria la implementación de una planificación urbana eficiente.Palabras clave: Eutrofización; Contaminación del agua; Calidad del agua; Río urbano.

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