Reservoir Water Quality Research Articles

Physicochemical assessment of Dhanmondi lake water in Dhaka city, Bangladesh

The main objective of this study was to examine the quality of water in the large reservoir of the Dhaka city lake and to determine whether it would be economically acceptable to purify this water for later use and to make it usable. The water quality parameters investigated are pH, temperature, electrical conductivity, hardness, alkalinity, total dissolved solids, total suspended solids, chloride, sulfate, phosphate, nitrite, nitrate, biochemical oxygen demand, chemical oxygen demand, and dissolved oxygen. The study has been done targeting three specific locations on Dhanmondi Lake, where crowds are comparatively the highest. This implies that there is a significant likelihood of pollution as well. The results of our 13-month study show that the quality of Dhanmondi lake water is somewhat higher than the international standard and some is at a tolerable level determined by the Bangladesh Department of Environment.

Climate services for water utilities: Lessons learnt from the case of the urban water supply to Valencia, Spain

Climate change projections in many regions of the world show a critical reduction in precipitation and a significant rise in temperatures in the next decades. This change may affect the operation of water utilities in arid and semi-arid parts of the globe. The Mediterranean region is particularly vulnerable to the impacts of climate change on water resources. In this paper, we reflect on the challenges that the water utility sector may experience during the upcoming decades to continue providing its essential service under the new climate scenario. Our reasoning is based on the lessons learned during the co-creation of a climate service with the water utility company of Valencia (Spain) within the framework of the EU ERA4CS project INNOVA. The joint vision of climate, water management researchers and water utility operators resulted in a multi-scale framework for evaluating the vulnerability of the water utility to climate change. The modelling framework couples water quantity and quality and their interaction in a chain of models. The proposed framework forced all parties to consider the issue of the temporal and spatial scales, and the importance of choosing and defining the boundaries of the problem. The analytical framework has three distinct elements: (1) a combination of climate projections; (2) hydrological and water resource management model of the river basin system; (3) reservoir management and water quality model. Two Representative Concentration Pathways (RCP) 4.5 and 8.5 were considered in two timeframes for the analysis: the short term (2020–2040) and the medium term (2041–2069). The results show a significant reduction in water availability combined with an increased frequency and intensity of phytoplankton blooms and anoxia episodes. These changes result in the deterioration of the reservoir trophic state, shifting from ultraoligotrophic-oligotrophic (control period) to oligotrophic-mesotrophic (RCP 8.5). The example shows how the combination of models on different scales and the involvement of experts in the co-creation process can result in a customized climate service that provides valuable information to water utility operators that can be used to reduce the system’s vulnerability to climate change.

A 16th century artificial reservoir under human pressure: water quality variability assessment in Laguna de Yuriria, central Mexico

This study assesses the variability of physicochemical and biochemical parameters, identifies principal pollutant sources, and characterizes water quality in Yuriria reservoir using water quality indexes in combination with multivariate statistical techniques. In situ parameters were measured in 55 reservoir sites including surface and deep points and in 7 associated channels. Moreover, major compounds and biochemical data were determined. Yuriria reservoir had alkaline, bicarbonate-mixed waters, with total dissolved solids (TDS) of 393.83 ± 3.43mg L-1. Water quality index (WQI) indicated a good class for agricultural irrigation but very poor and poor classes for preservation of aquatic life. The nutrient inputs and the internal nitrogen recycling triggered a hypereutrophic status in the reservoir. The decomposition of residual biomass from aquatic macrophytes contributed to reduce dissolved oxygen (DO) in the hypolimnetic waters (mean DO = 3.86mg L-1). Statistical analysis revealed that the study area is highly exposed to anthropogenic stress and in a lesser extent to natural processes. Urban and agriculture runoff enhanced the salinization and the generation of solid particles which deteriorated water quality. Chemical oxygen demand (COD), biochemical oxygen demand (BOD), and NO3--N presented a common anthropogenic origin by external (point and diffuse) and internal pollution sources, while a diffuse source (agricultural activities) was reveled for phosphorus. This study is important to be used in systematic monitoring and sustainable co-management programs and for formulating the necessary strategies to remediate the Yuriria reservoir water quality and extrapolate to other reservoirs worldwide.

Lake management under severe drought: Lake Mead, Nevada/Arizona

AbstractDrought can affect both the quantity and quality of water in lakes and reservoirs, yet larger, highly managed waterbodies, such as Lake Mead, may be somewhat buffered from drought effects. From 2000 to present, Lake Mead has experienced a 71% decline in volume; however, influent water quality has remained high and consistent outflow volumes through Hoover Dam have been maintained. Furthermore, management activities, such as increased removal of phosphorus by wastewater dischargers and legacy contamination cleanup efforts, have been initiated since the drought began. These efforts have led to small improvements in values of water quality parameters, such as phosphorus, nitrogen, and perchlorate, despite loss of volume for dilution of constituents, and consequently, decreased residence time. As the drought continues, Lake Mead is projected to continue declining in volume, inflows are projected to become warmer, and the population of Las Vegas is projected to grow, potentially adding additional stress to the hydrologic system. Maintenance of outflow may mitigate some potentially negative consequences, and understanding the drivers behind continued high water quality despite prolonged drought is important to continue to maintain the health and vitality of the entire Lower Colorado River Basin.

Water Quality Status and Water Quality Index of Selulu Reservoir, East Kalimantan, Indonesia

Selulu Reservoir is located in Waru District, North Panajam Paser Regency. It is one of the tourist destinations in supporting the tourism sector. Land use changes and urbanization have potential impacts on the environment. This study aimed to determine Water Quality Status and Water Quality Index (WQI) in Selulu Reservoir. Hopefully, the result will become the basis for future reservoir management to keep the water quality well. The method in this study used the survey method. These research steps include surveys, water samples, laboratory analysis, and data analysis. Parameters analyzed include temperature, pH, BOD, COD, and DO. The results showed that the reservoir’s water quality in all samples still met the standard, except for pH at point 3. The difference fluctuating value found in COD at point 3, although it still meets the standard. This location is close to residential areas that dump their waste into the reservoir. The Water Quality Status of the reservoir still meets the standards, and WQI is in the excellent category. This is due to the dominant land use of forest and plantations with few settlements around the reservoir, domestic waste is small, and the reservoir capacity is still supportive. Management is needed to maintain reservoir water quality in the future.

Environmental assessment of the water quality of the Kaniv reservoir

Safe drinking water is a basic requirement for good health. Fresh water is already a limited resource in many parts of the world. In the next century, it will become even more limited due to population growth, urbanization and climate change. Purpose. Provide a comprehensive assessment of the water quality of the Kaniv Reservoir based on the calculation of the Water Quality Index (WQI). Methods. Analytical-synthetic method, geo-information (cartographic modeling), analysis of information sources, mathematical modeling. Results. There is an increase in BOD, COD and dissolved oxygen content in the area of the Kaniv Reservoir from the hydropost 500 m above the Bortnytsky Aeration Station (BAS) to the hydropost 2 km below the Kanivska Hydropower Station’s dam. The only exception is the hydropost 500 m below the BAS, for which the corresponding values are the largest, and the BOD indicator exceeds the established standards by 1.5 times. Ammonium content 500 m below BAS exceeds the standards established by Directive 98/83/EC by almost 3 times. Exceeding the normative values for the content of sulfates and chlorides and suspended substances were not recorded. The least polluted water is observed at hydrostations located below Ukrainka and Pereyaslav-Khmelnytskyi. The highest value of the water quality index is 242, which is typical for the hydropost 500 m above the BAS and corresponds to the value of the worst quality. Conclusions. It was in the immediate vicinity of the city of Kyiv that the water turned out to be the most polluted. This may indicate the imperfection of industrial, domestic and agricultural wastewater treatment systems. For the hydropost 500 m below the BAS, excesses of the normative values for the parameters of ammonium and BOD content were also recorded, while other parameters are either at the limit of the norm or approaching it. Studies of the water quality of the Kaniv Reservoir showed that its quality according to the WQI indicator varies from 59 to 242 (from low to the worst). Accordingly, such water, in the absence of another source, can be used for drinking after passing proper multi-stage purification.

Environmental risk assessments of uses cyanide in gold extraction on water quality parameters and its effect on rhodanese activities in selected organs of coptodon zillii in igun reservoir, Southwestern, Nigeria

This study was conducted to investigate the effect of cyanide on the pattern of rhodanese activity distribution in selected organs of Coptodon zillii and water quality of Igun reservoir. Fish and water samples were collected monthly for period of a year to cover both seasons. The physical parameters such as air and water temperature, conductivity, TDS, pH, depth, and transparency were determined. Air temperature and water temperature were determined in situ with a mercury-in-glass thermometer, pH and TDS were determined by calibrated pH meter (PCE-PHD Version 1.1 Model Q656697). Selected organs such as gill, fillet, and liver were used for rhodanese activity analysis while physico-chemical parameters were analyzed based on APHA (2012) standard methods. The pH concentration recorded in this study ranged from 7.1 - 8.1 with a mean of 7.48 ± 0.47 while highest pH mean concentration was observed in dry season (7.61 ± 0.5) compared with the rainy season (7.36 ± 0.24). The mean cyanide concentration was high during the rainy season (0.09 ± 0.03 mg/L) compared with dry season (0.07 ± 0.04 mg/L). The results of rhodanese activity recorded in the gills, fillet, and liver of Coptodon zillii (3.66 ± 3.19 RU/mg, 3.73 ± 2.58 RU/mg, and 3.73 ± 2.68 RU/mg) respectively. Water temperature, pH, and depth showed a positive correlation with rhodanese activity in the gills while a negative correlation was observed between water temperature and rhodanese in the fillet and liver of Coptodon zilllii. Based on the cyanide concentration recorded in this study shown that Igun reservoir is polluted which can be can harmful to humans and other organisms could due to archaic gold mining method using by local miner around the reservoir. Coptodon zillii inhabiting the reservoir showed a high concentration of rhodanese in the different tissues that could serve as the detoxifying mechanism. However, further biochemical analysis of others fish tissue should be examined to determine the effects of mining pollutants on aquatic biota.

Dissolved oxygen concentration and eutrophication evaluation in Yamchi dam reservoir, Ardabil, Iran

One of the essential issues in the quality management of water resources is the determination of the level of eutrophication and dissolved oxygen in dam reservoirs and other water bodies. It is possible to study changes in dissolved oxygen concentration using qualitative models. In this study, CE-QUAL-W2, a two-dimensional model of hydrodynamics and water quality capable of predicting the behavior of aquatic ecosystems, has been used to simulate dissolved oxygen concentration and eutrophication. As a case study, the water quality of the Yamchi dam reservoir, located in Ardabil Province, has been qualitatively investigated using the CE-QUAL-W2 model. Based on the geographical location of the Yamchi dam reservoir, it includes warm monomictic basins. According to the results, the dissolved oxygen concentration in the simulation period varied between 0 and 12 mg/L. In autumn and winter, this concentration was almost uniform at various depths. However, in summer, a sharp decrease in dissolved oxygen concentration, to less than 2 mg/L in the bottom layers, was observed, which is due to the presence of nutrients. Regarding eutrophication, the Yamchi dam reservoir is one of the eutrophic reservoirs, and practical strategies should be employed to improve these conditions. Recommended strategies include reducing the retention time of water in the reservoir, dewatering from the underlying layers during the thermal stratification period, and preventing the entry of agricultural drains into the inlet tributaries of the reservoir.

The effect of reservoir expansion from underground karst cave to surface reservoir on water quality in southwestern China.

Due to the excessive exploitation of traditional energy sources, the attention paid to water energy has increased in recent years. As an important means to effectively utilize water energy, reservoirs play an important role in drinking water, irrigation, flood control, and drought resistance. However, utilizing reservoirs often led to water quality issues resulting from the interaction of nutrients and hydrological conditions, especially due to the special structure of karst areas. Because of the change of hydrological conditions by the effect of dam construction, the dynamic of water quality will be more obvious in karst areas with a fast exchange of water and contaminants between underground and surface streams. In the present study, the change in water quality of a karst reservoir, the Muzhu Reservoir in the Houzhai Catchment, was studied. Long-term monitored datasets (1981-2002) and water quality datasets of more recent years were used to assess the effect on the water quality of reservoir expansion from the underground reservoir to the surface reservoir in a karst area. Long-term series datasets had shown that the hydro-chemistry type had been changed from HCO3-·SO42--Ca2+·Mg2+ type to HCO3--Ca2+ type in the short term after the reservoir's expansion. The chemical components of water originating from a rock background reduced markedly after the reservoir's expansion, whereas the content of the anthropogenic contribution in the water decreased after the expansion, except in April and May. Isotopic characteristics showed that δ15N-NO3- and δ18O-NO3- values were positively correlated before and after the reservoir expansion, but the slope of the linear regression before the expansion was 0.34, while the slope of the linear regression before the expansion was close to 0.7. This indicated that although denitrification and assimilation may occur simultaneously after the reservoir's expansion, the role of denitrification on nitrate removal decreased, which resulted in nitrate accumulation in the karst reservoir. The results highlighted that nitrate accumulation in karst reservoirs should be monitored to decrease nitrate concentration in the future.

Predicting anoxia in the wet and dry periods of tropical semiarid reservoirs

The dissolved oxygen (DO) level in the hypolimnion of lakes and reservoirs can reach anoxic conditions, which favor the release of phosphorus from the sediment bed to the water column. However, to estimate nutrient release from sediment is extremely important to quantify the duration of anoxia. In low latitude regions, the water-sediment layer is warmer than in temperate regions and eutrophication is usually more severe, potentially accelerating oxygen depletion and extending the anoxia period. Considering that the available equations to quantify the duration of anoxia were developed for temperate lakes, there is a need to effectively quantify this period in lakes and reservoirs located in other climate regions, such as the semiarid. In this study, the dynamics of thermal stratification was analyzed as a function of the Relative Water Column Stability coefficient (RWCS) and then correlated with DO dynamics for nineteen tropical semiarid reservoirs. RWCS values were higher during the rainy season, when anoxia duration was longer and the hypolimnion was thicker with respect to total water depth. Then, two new equations for quantification of anoxia duration, based on the equation originally developed for temperate climate, were adapted for the wet and dry seasons of the tropical semiarid region. The results showed that the proposed equations presented a better performance compared to the original one, which tends to underestimate anoxia in tropical semiarid reservoirs. This work intended to provide simple and locally adjusted tools to better quantify anoxic events and support the water quality and internal phosphorus load modeling for tropical semiarid reservoirs.

Simulation on water quality of reservoir at construction phase by pollutant release from oxidation of waste rocks rich S and Fe

The presence of sulfur and iron in waste rocks produced during reservoir construction can generate acid rock drainage (ARD). Its environmental impact however, has often been neglected. Therefore, lab experiments were firstly conducted to simulate the release of main pollutants when the waste rocks having been submerged at the bottom of a reservoir in Guizhou Province, China. The impact of pollutants released on water quality during impounding was then predicted by a two-dimensional model MIKE21 coupled with ECO Lab module. Results showed that the argillaceous rock mainly produced acid and sulfate through oxidation. Based on release experiment, the model suggested that the average concentrations of TP, SO 4 2- , and Fe 3＋ peaked rapidly in the cross section about 100 m downstream of the waste rock yards when water level reached 855 m. At this point, the average Fe 3＋ concentration exceeded the standards of drinking water source and remained for 6 days, while the average TP concentration downstream exceeded the standards for 60 days. The water quality would meet the standards because of the dilution effect on pollutants when the water level was above 883 m. However, the release of phosphate from combined cycles of “P-Fe-S” should be paid more attention during impoundment. Based on the simulation results and existing actual cases, it showed that the anaerobic environment caused by impoundment can significantly reduce the negative impact from ARD. The study would provide a new insight for the stacking of engineering waste rocks and environmental risk assessment of the reservoir under construction. • Impact on water quality by waste rocks during reservoir construction was simulated. • SO 4 2- , TP and Fe 3+ mainly came from argillaceous rock through microbial oxidation. • P released from waste rocks through combined cycles of “P-Fe-S” should be concerned. • The pollutants migrated downstream to the front of the dam with water level rise. • Anaerobic environment due to impoundment reduced the impact of ARD from waste rocks.

Water Quality Variation Law and Prediction Method of a Small Reservoir in China

Compared with the attention of large reservoirs, the water quality of small reservoirs also needs attention. In recent years, the problem of reservoir water quality has become increasingly serious. How to predict reservoir water quality may be an urgent problem to be solved. Taking the Yangmeiling reservoir as an example, this paper collects the hydrological and water quality data of the Yangmeiling reservoir in the last ten years, analyzes the relationship between hydrological and water quality data, and uses a machine learning method to simulate the relationship between water quality and hydrological data. The results show that the water quality of small reservoirs can be simply linked with hydrological data and can be predicted through hydrological data, and has high simulation accuracy. This method can be popularized in the simulation and prediction of the water quality of small reservoirs; it does not provide a theoretical basis for the water quality management of small reservoirs.

The effect of the gypsum formation on the water quality of reservoirs: A case study of Kosar dam basin, Iran

The principal objectives of this study are the identification of the dissolution rate of gypsum formations and their effect on reservoir water quality. In this regard, total dissolved solids (TDS), calcium, and sulfate concentration were simulated using both the completely mixed model and a two-dimensional model, CE-QUAL-W2, in Kosar dam, Iran. The proposed method attempts to reduce the defects of the past laboratory methods such as the rotary disk and the channel flow cell, using real data and conditions. Moreover, long-term quality data were used. Finally, the average dissolution rate for calcium and sulfate, and TDS flux were calculated in two scenarios.

A coupled streamflow and water temperature (VIC-RBM-CE-QUAL-W2) model for the Nechako Reservoir

Study regionNechako Reservoir, British Columbia, Canada. Study focusHydrological regulation affect both hydrological and thermal conditions in the reservoir and downstream reach, subsequently disrupting fish habitats. This paper aims at developing an integrated model simulating physical processes that govern the quantity and quality of inflow, reservoir, and outflow water of the Nechako Reservoir. Such a model would help stakeholders understand the response of in-reservoir water temperature stratification and downstream water temperature to changes in inflow and reservoir operation under future climate change. New hydrological insights for the regionThe model was calibrated against historical reservoir levels and in-reservoir and outlet water temperature field data. The integrated model simulated accurately the wide variation of reservoir levels as well as the in-reservoir water temperature at Kenney Dam and the outlet temperature. Sensitivity analysis shows that reservoir water temperature particularly the epilimnion is sensitive to changes in both meteorological and hydrological forcing. Forcing the model with different outflow scenarios shows the weak sensitivity of temperature of water released to outflow rates. Given epilimnion water releases at the spillway, the Summer Temperature Management Program could be inefficient to provide cool water in the Nechako River during the critical period of salmon migration in a warming climate. However, colder water remains available at depth at Kenney Dam to potentially mitigate and better control downstream water temperature.

THE CURRENT ICHTHYOTOXICOLOGICAL STATE OF THE NARVA RESERVOIR

Reservoirs are a special category of inland water bodies with specific features of water exchange, flow and level fluctuations. The quality of water in reservoirs is formed under the influence of three factors: natural and economic conditions for the formation of runoff in the catchment area, the quantity and quality of wastewater, atmospheric emissions of pollutants, and processes occurring in the reservoir itself. The quality of water in individual water areas of reservoirs is also heterogeneous. The article deals with the issue of the current ichthyotoxicological state of the Narva reservoir, a reservoir of fishery importance, two decades ago one of the most polluted in the North-West of Russia, which manifested itself in the total defeat of fish by toxicosis and cases of their death. This was due to a powerful anthropogenic load and the entry of pollutants in various ways, and especially by the aerogenic route. The present study is associated with a decrease in anthropogenic load as a result of a decrease in the operation of the Narva and Baltic thermal power plants (TPP). As a result of analytical studies in a number of water areas of the reservoir, it was shown that the reduction of anthropogenic load primarily affected the condition of fish as generally accepted indicators of water quality and habitat – the percentage of toxicosis damage and the severity of the pathological process decreased. The reduction of anthropogenic load was shown by the results of biotesting and materials of chemical-analytical research.

Sobol sensitivity analysis for non-carcinogenic health risk assessment and water quality index for Kohgiluyeh and Boyer-Ahmad Province, Western Iran

Human activities and climate may have an impact on the water quality of reservoirs. Therefore, the present research aims to use the entropy water quality index assessment technique to analyze the water quality features of the main water supply reservoirs as well as to investigate the effect of water parameters on the water quality of the reservoirs. In this study, the total non-carcinogenic health risks from various exposure paths were estimated for adults and children. The water quality of the major water supply reservoirs in Kohgiluyeh and Boyer-Ahmad province was typically poor and unfit for human consumption. Besides, the non-carcinogenic risk was higher in males (0.958–1.497) and children (1.065–1.664) than in females (0.879–1.374) according to health risk assessments. Among the factors under study, magnesium and nitrate had the highest influence on the non-carcinogenic risk. Finally, the sensitivity of each of the parameters affecting the non-carcinogenic risk was assessed using Sobel sensitivity analysis. The results indicated that the nitrate concentration (Cw) and Ingestion Rate (IR) were the most sensitive in the oral state, while Cw and fraction of skin’s surface area (F) were more sensitive in the dermal state.

Hydrochemistry of an ancient traditional irrigation reservoir in Padaviya, Sri Lanka

Padaviya Wewa Reservoir constructed in 2nd century BC is an important traditional reservoir in Sri Lanka. The construction and the use of these traditional Sri Lankan reservoirs are different from modern large-scale hydroelectric and multi-purpose reservoirs in Sri Lanka and the rest of the world. The hydrochemistry of these unique water bodies has been rarely studied and understood. In this study, depth-wise distribution of Fe, Mn, Zn, Cd, and As and their correlation with pH, dissolved oxygen, conductivity, temperature, BOD, COD, and total phosphate were investigated to identify the mechanisms that drive the water quality in Padaviya Wewa Reservoir. There is a well distinguishable chemical gradient from the surface to the bottom of the water column suggesting that Padaviya is not a well-mixed water body even though the maximum water depth during the study period was 4.75 m. There was a strong negative correlation between Fe, Mn, Zn, and Cd and DO in both surface and bottom waters. In addition, a strong positive correlation between Fe, Mn, Zn, Cd, and As, and total phosphate was observed in bottom waters. The suggested driving force behind the depth-wise distribution of chemical species is intense biological activities in the reservoir. The weak thermal stratification is strengthened by photosynthesis at the surface waters and organic matter degradation at bottom of the reservoir. The end-result of these biological activities are oxygen rich surface waters with low concentrations of nutrients and metal ions and oxygen depleted bottom waters with higher concentrations of nutrients and metal ions.

Nonlinear multidecadal trends in organic matter dynamics in Midwest reservoirs are a function of variable hydroclimate

AbstractDissolved organic matter (DOM) and particulate organic matter (POM) can influence biogeochemical processes in aquatic systems. An understanding, however, of the source, composition, and processes driving inland reservoir organic matter (OM) cycling at a regional scale over the long term is currently unexplored. Here, we quantify decadal patterns (> 20 yr) of DOM quantity and composition and POM in 40 reservoirs in the midcontinent United States. We built 184 Random Forest models to identify how the relative influence of watershed characteristics and limnological parameters on OM dynamics may vary over time and in synchrony with hydroclimatic anomalies. The reservoir OM quantity and composition varied nonmonotonically through time and in contrast to lake browning observed in the northern hemisphere. Reservoir DOM composition switched from humic and aromatic during wet summers to aliphatic, potentially autochthonous DOM during particularly prolonged dry summers in the mid‐2000s. The shift in reservoir DOM quantity and composition could be attributed to the change in time‐varying control of watershed and limnological factors mediated by the hydroclimatic conditions. Watershed control (e.g., percent crops) was predominant during wet summers, while the effect of reservoir morphology (e.g., maximum depth) and water quality parameters (e.g., Secchi depth, chlorophyll a) were evident during dry summers. Thus, future predictions of drier conditions may promote “greening” with negative implications for reservoir water quality and treated drinking water. Considering the nonlinear nature of reservoir OM dynamics and its controls will help to better mitigate water quality issues in these constructed systems increasingly impacted by global changes.

Analysis of Water Quality Status of Cengklik Reservoir based on Pollution Index, Boyolali Regency, Central Java, Indonesia

Anthropogenic activities such as fishing, fish ponds, and domestic trash contribute the most to the water quality of the Cengklik reservoir. This research aimed to analyze the water quality status and Pollution Index of the Cengklik reservoir. Water quality status was calculated by using the Pollution Index method. The results indicated that the water quality of the Cengklik Reservoir is strongly influenced by the sources of water pollutants and the surrounding area's ambient conditions. The results revealed that the water quality at the inlet is lightly polluted, with pollutant index values (Pij) of 2.56 at the inlet (CI1) and 4.02 at the inlet (CI2).

Zooplankton community of Bakreswar reservoir: Assessment and visualization of distribution pattern using self-organizing maps

Self-organizing maps, otherwise known as Kohonen-maps, are one form of unsupervised artificial neural networks that can produce two-dimensional plots from multidimensional data. This tool is especially useful in community pattern analyses and has been previously used in spatial pattern analysis with different perspectives. The present study aims to find zooplankton's community pattern in the Bakreswar reservoir ecosystem. Bakreswar reservoir is a freshwater ecosystem in the Birbhum district of West Bengal, India. The reservoir is primarily used to supply freshwater to the Bakreswar thermal power plant. However, the local villages around the reservoir depend on it for drinking water and fishing sustenance. The data used in this study was collected over two years from three different stations. Thus, in addition to describing the spatial pattern of community distribution of zooplankton groups, the temporal variation was also studied. It is observed in the study that the four major groups of zooplankton – Copepoda, Cladocera, Ostracoda, and Rotifera – react differently to the different environmental attributes. Primarily directed by the physical environmental factors, the effect of the chemical factors on the patterning is also evident from the study. Copepods are the dominant group in the system, closely followed by cladocerans and rotifers. But this observation changes at different stations and throughout the study period. The temperature profiles of the reservoir primarily direct the occurrence of ostracods and rotifers, whereas cladocerans and copepods are inclined more towards a chemical factor directive. Rotifers are dominant in the monsoon, whereas the post-monsoon and winter seasons show an increased presence of copepods and cladocerans. The overall observation that the reservoir's water quality is good, and the trophic structure is healthy is in accordance with previous studies as well.