Water Discharge Rate Research Articles

Analysis of Local Scour around Double Piers in Tandem Arrangement in an S-Shaped Channel under Ice-Jammed Flow Conditions

The stability of bridge foundations is affected by local scour, and the formation of ice jams exacerbates local scour around bridge piers. These processes, particularly the evolution of ice jams and local scour around piers, are more complex in curved sections than in straight sections. This study, based on experiments in an S-shaped channel, investigates how various factors—the flow Froude number, ice–water discharge rate, median particle diameter, pier spacing, and pier diameter—affect the maximum local scour depth around double piers in tandem and the distribution of ice jam thickness. The results indicate that under ice-jammed flow conditions, the maximum local scour depth around double piers in tandem is positively correlated with the ice–water discharge rate, pier spacing, and pier diameter and negatively correlated with median particle diameter. The maximum local scour depth is positively correlated with the flow Froude number when it ranges from 0.1 to 0.114, peaking at 0.114. Above this value, the correlation becomes negative. In curved channels, the arrangement of double piers in tandem substantially influences ice jam thickness distribution, with increases in pier diameter and spacing directly correlating with greater ice jam thickness at each cross-section. Furthermore, ice jam thickness is responsive to flow conditions, escalating with higher ice–water discharge rates and decreasing flow Froude numbers.

Water provision benefits from karst ecosystems: An example for Watuputih groundwater basin, North Kendeng Mountain, Indonesia

Karst ecosystems offer a wealth of ecosystem services, but their protection is increasingly challenging due to degradation and land-use conversion, including limestone mining. This study investigates the water provision service derived from karst ecosystems threatened by limestone mining in the Watuputih groundwater basin, Central Java, Indonesia. Water supply was quantified by measuring water discharge rates from major springs around the basin. Water usage was quantified for household consumption, agriculture, and recreation. This study also measured water infiltration rates in mining and non-mining areas to indicate the effects of limestone mining to hydrological processes. This study identified three primary springs around the basin: Sumber Seribu spring, Brubulan spring, and Kalutan spring, with discharge rates of 1,080 liters per second, 85 liters per second, and 0.76 liters per second, respectively. A local water company extracts water from Sumber Seribu spring at a rate of 80 liters per second to supply approximately 57,600 individuals. The water supply from the three springs can irrigate approximately 1,594 hectares of rice fields. Water from Sumber Seribu spring also supports recreational activities in Sumber Semen recreation park, attracting an average of 19,173 visitors per year. This study revealed a complete impairment of soil's water infiltration capacity in limestone mining areas. These findings underscore the pressing need to safeguard the Watuputih groundwater basin and to mitigate the detrimental effects of limestone mining on hydrological processes. This involves designating the Watuputih karst ecosystem as a protected area, implementing Payment for Ecosystem Services (PES) programs, and restoring degraded post-mining sites.

Assessing the nutrient removal performance from rice-crayfish paddy fields by an ecological ditch-wetland system

Agricultural drainage from catchments significantly impacts aquatic ecosystems due to high nitrogen and phosphorus concentrations in runoff. While original ecological ditches and wetlands have demonstrated effectiveness in nutrient load removal, the overall impact of an ecological ditch-wetland system (EDWS) on agricultural nutrient removal has received limited attention. This study conducted a field experiment to investigate the physicochemical conditions and nutrient removal efficiency of an EDWS for purifying nutrient discharge from rice-crayfish paddy fields. Variations in water temperature (WT), dissolved oxygen (DO), pH, and total suspended solids (TSS) within the EDWS were assessed. Nutrient concentrations—including total nitrogen (TN), ammonium nitrogen (NH4-N), nitrate nitrogen (NO3-N), total phosphorus (TP), and soluble reactive phosphorus (SRP)—were monitored from the tillering to the ripening stage of the rice growth cycle. The evaluation of nutrient removal efficiencies in the EDWS revealed that ecological ditches exhibited higher removal efficiencies compared to wetlands. The average total removal efficiencies for TN, NH4-N, NO3-N, TP, and SRP were 37.50 %, 39.38 %, 38.62 %, 37.94 %, and 39.51 %, respectively, with peak removal efficiencies observed at specific growth stages of the rice crop. Furthermore, the study explored the influence of hydraulic retention time on nutrient removal efficiency in the EDWS, indicating higher nutrient discharge removal efficiencies under low water discharge rates. Linear regression analysis identified water discharge, influent nutrient loads, and TSS as significant factors affecting nutrient removal efficiency in the EDWS. This study provides valuable insights into the effectiveness of EDWS in purifying nutrient discharge from rice-crayfish paddy fields, highlighting their potential as sustainable solutions for nutrient management in agricultural landscapes.

Mining impacts peatland hydrology reducing discharge and water storage volumes

Peatlands cover about 3% of the Earth’s land surface, but are the largest terrestrial carbon store and are important for freshwater storage. In Australia, nationally protected peatlands (called upland swamps) exist in the catchment headwaters for Sydney’s drinking water supply. In this region, longwall mining of underground coal seams can result in subsurface fracturing, land subsidence, and, potentially, peatland drainage. This study presents the water balance modelling results for an upland peat swamp before and after it was undermined in 2020. Following a detailed field campaign, a conceptual lumped hydrology model was developed to estimate the local water balance, with a Nash Sutcliffe Efficiency of 0.85 for the modelled storage of the intact swamp. After undermining, the water balance of the swamp changed, with higher deep seepage rates and reduced surface water discharge rates. For the first time, these findings detail the hydrologic effects of longwall mining on peatland environments. Based on these findings, broader catchment management initiatives are recommended to prevent or limit further water extraction from upland swamps, including incidental water losses associated with subsidence.

Rainfall Dependency and Water quality Assessment of springs of three villages of Rudraprayag District: An analysis of veins of Uttarakhand Himalaya

A spring is a crevice in the substrate that forms naturally and allows water to pour out directly from the earths subsurface. Every major river in the country has a system of springs that serve as a symbolic representation of its source. But this very fundamental source of many resources is in peril. The problem is mainly related with the reduced discharge rate of water from the spring. The reason of truncate discharge rate is variability in the rainfall pattern in the recharge area due to the climate change over the years.To ensure the quality and security of the public's water supply, regular quality assessments of drinking water sources are required. In consequence, this study not only analyse the rainfall dependency of springs but also evaluated the spring water quality for drinking, using water quality index, in three villages located in Jakholi block of Rudraparayag district, Uttarakhand. The ten foremost physiochemical elements that regulate water quality—Nitrate, Fluoride, Iron, pH, Turbidity, Chloride, Residual Chlorine, Magnesium, sulphate, and Hardness—were investigated to ensure compliance with guidelines defined by the Bureau of Indian Standards IS: 12500:2012. After examining the data, it became apparent that all of the indicators pointed to acceptable water quality, making it ideal for drinking. However, because of its low discharge and great reliance on rainfall, its position is getting more detrimental.

Controlling stormwater detention ponds under partial observability

Stormwater detention ponds play an important role in urban water management for collecting and conveying rainfall runoff from urban catchment areas to nearby streams. Their purpose is not only to avoid flooding but also to reduce stream erosion and degradation caused by the direct discharge of pollutants to the stream. We model the problem of controlling the discharge rate of water from the ponds as a partially observable hybrid Markov decision process and subsequently use Uppaal Stratego for synthesizing safe and near optimal control strategies. The generated strategies are based on noisy sensor measurements of the water height in the pond, hence the underlying system is only partially observable. We present results analyzing how sensitive the synthesized strategies are with respect to the accuracy of the measurement sensors in both offline and online settings. These types of analyses not only provide insight into the robustness of the generated strategies, but they can also be used for deciding on which measurement sensors to use, thereby balancing sensor cost and accuracy.

Modeling of some hydrodynamics characteristics of Orashi River in the Southern Region of Nigeria

The dynamic nature of rivers and its effect on the inhabitants and its surroundings is of fundamental concern to Hydro Scientists, Coastal Engineers, and Surveyors. These changes have remained unpredicted and hence the focus of this study. The aim of this study is to develop a geo-model of the dynamics of Orashi River in Ogba/ Egbema/ Ndoni Local Government Area of Rivers State. The objectives are to determine the river dynamics parameters, to develop a functional multiple regression model of Orashi River dynamics and to determine the percentage contributions of each of the independent variables. This study was carried out using classical survey methods such as river current measurement, river cross-sectional area determination, river water discharge rate determination, bathymetric operation, runoff water computation, water gauge reading and conventional ground surveying. A multiple regression analysis was carried out using data obtained in 2013, 2015 and 2017 used as the independent variables while the river level changes is used as the dependent variable. The result of this study show changes in the river current and river discharge. The data analysis show the contribution of the independent variable to the dynamics of Orashi River for 2013 to be 24.83%, 30.63%, 20.24%, 0.33% and 24.97% for river current, runoff peak discharge, rainfall intensity, temperature and humidity respectively. The analysis was also carried out in 2015 & 2017and different results were obtained. A functional model of the dynamics of the changes in Orashi River was developed for 2013, 2015 and 2017 which can be used in monitoring the changes in Orashi River.

Reinforcement treatment of dredging sludge using a novel method of electro-osmosis vacuum preloading

This case study proposed a novel electro-osmosis PRD vacuum preloading method to solve dredging sludge treatment issues: difficulty in draining from soil showing large volume, non-uniform settlement, and low strength. To verify the effectiveness of the new method, four kinds of physical model tests integrating particle image velocimetry (PIV) technique of traditional vacuum preloading (VP), prefabricated radiant drain vacuum preloading (PRD-VP), electro-osmotic vacuum preloading (EO-VP), and EO-PRD-VP methods are conducted. The water discharge, average surface settlement, pore water pressure, water content, and undrained shear strength after treatment, clogging range, relationship between clogging range and water discharge rate, and relationship between clogging range and average surface settlement are investigated. For those model tests, it is demonstrated that EO-PRD-VP method has the best advantage in volume reduction, uniform settlement, and strength improvement. Water discharge is enlarged by 13–33%. The differential settlement can reach 2.3 cm, decreased by 28–56%. The undrained shear strength can reach 12 kPa, increased by 1–2 times. In addition, the clogging range development is described, for the given water discharge rate and average surface settlement, clogging range of EO-PRD-VP method is the minimum. The empirical equations between clogging range and water discharge rate, clogging range, and average surface settlement are established to predict the clogging range, which can lay the foundation for developing the consolidation theory of EO-PRD-VP method.

The Flow Rate of the Condenser Cooling Water in the Distillation Process Increases the Quality and Quantity of Patchouli Oil.

Indonesia is an important essential oil-exporting country globally, where 40 types of essential oils have been traded on the international market and are products of Indonesia. However, the quality and quantity of patchouli oil produced in Indonesia are still low. Most essential oil processing units use simple or traditional technology and generally have limited production capacity. This study aimed to obtain the optimum water flow rate in a condenser system for patchouli oil production in Maluku, Indonesia. Patchouli oil extraction from fresh patchouli leaves and twigs was carried out by increasing the condenser water discharge rate. Patchouli oil extraction with a condenser cooling water discharge treatment of 1.74 L/min and drying time for 5 days produced the highest patchouli oil yield of 1.4%. The greater the condenser water discharge rate, the better the yield and accumulation of patchouli oil recovery obtained. In addition, based on the results of the analysis of the composition of patchouli oil compounds with GCMS, it can be seen that 13 compounds can be detected in patchouli oil. The three main components of patchouli oil in all condenser cooling water treatments were alpha-guaiene, delta-guaiene, and patchouli alcohol. Considering the results of all parameters mentioned above, the treatment of the condenser cooling water discharge of 1.74 L/min and drying time for 5 days increases the quality and quantity of patchouli oil.

Fossilized autogenic responses of grain‐size transition to sediment supply and water discharge: Alluvial fan experiments

ABSTRACTAutogenic feedbacks can produce large‐scale, organized stratigraphic patterns in alluvial fans, but autogenic depositional signatures of specific upstream boundary conditions remain challenging to interpret. Here, a combination of theory, experiment and field application is used to explore how autogenic lithofacies changes can be interpreted as stratigraphic indicators of upstream boundary conditions. Six experiments were conducted to test the effects of sediment supply and water discharge rates on autogenic advance and retreat of the lithofacies boundary (grain‐size transition) in an alluvial fan with two dominant grain sizes. Migration of the grain‐size transition caused a short‐term zigzag pattern in the grain‐size transition position in the dip‐directional deposit section. For each experiment, time‐lapse images and laser topographic scans of the fan surface and stratigraphic cross‐sections of the final deposits were used to quantify characteristic timescales of autogenic processes. Timescales for fan‐margin migration, surface wet‐fraction change and grain‐size transition migration generally shorten as sediment supply rate increases and water discharge rate decreases. Increasing the sediment supply rate shortens the duration of the fluvial sediment storage and release cycle, producing higher frequency zigzags in the grain‐size transition trajectory. Increasing the water discharge tends to widen channels and lengthens the duration of the fluvial sediment storage and release cycle, constructing lower frequency zigzags in the grain‐size transition trajectory. Increasing the water discharge also enables more sediment to transport further downstream during release events, leading to higher magnitude zigzags in the grain‐size transition trajectory. These relationships between upstream boundary conditions and the grain‐size transition trajectory demonstrate how autogenic stratigraphic signals could be used as a tool to infer relative changes in boundary conditions.

Synergistic effects of microencapsulated bacterial spores and superabsorbent polymer on self-healing performance in mortar

This study explores the feasibility of utilizing a superabsorbent polymer (SAP) to improve the self-healing performance of microbial-induced calcium carbonate precipitation (MICP) in cement-based materials. The amount of microencapsulated bacterial spores was varied from 0.25–1 % by cement weight. The SAP content was set to either 0 or 4 % by cement weight. As additives, the impact of SAP and MICP bacteria on mortar properties, including flowability and compressive strength, was assessed. The self-healing performance was evaluated based on crack-healing percentage and water permeability recovery. Microstructural analyses, including thermogravimetry/differential thermal analysis (TG/DTA), X-ray diffraction (XRD), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), were performed to investigate the microstructural and chemical changes during the healing process. The findings revealed that specimens exclusively mixed with 4 % SAP exhibited a slightly lower crack-closure efficiency compared to those mixed exclusively with 1 % MICP bacteria. However, the SAP-containing specimens exhibited a higher degree of permeability recovery. Meanwhile, in the binary additive system with 0.5 % MICP bacteria and 4 % SAP, the specimens exhibited the highest crack-closure percentage of 91 % and a final water discharge rate of 15 mL/min after 45 days of healing. In contrast, specimens mixed exclusively with 1 % MICP bacteria showed a crack-closure percentage of 76 % and a final water discharge rate of 59 mL/min. These results suggest that incorporating SAP into the MICP system enables a reduction in MICP bacterial content without compromising self-healing performance.

ОСОБЕННОСТИ ВНУТРИСУТОЧНЫХ КОЛЕБАНИЙ ПОКАЗАТЕЛЕЙ КАЧЕСТВА ВОДЫ, НАБЛЮДАЕМЫХ В КАМСКОМ ВОДОХРАНИЛИЩЕ9

To solve a wide range of problems related to the protection and rational use of water bodies, it is fundamentallyimportant to assess fluctuations in the variability of indicators of their chemical composition. In this case, as a rule, seasonal and monthly fluctuations are considered and analyzed. This is due, most of all, to the features of the current monitoring system. The transition to automated measurement systems makes it possible to study and analyze much shorter-period processes, such as inter- andintra-day fluctuations.Currently, these fluctuations in water quality indicators in reservoirs are an insufficiently studied phenomenon, although theyplay an important role both in shaping the consumer properties of water and ensuring the environmental safety of water bodies. Thesefluctuations are especially relevant for water bodies located in zones of active technogenesis, which are the most important sources ofwater supply for the largest industrial complexes.The article examines the processes recorded in two sections of the Kama Reservoir: the lower one, directly adjacent to theKama Hydroelectric Power Station, and the upper one, located in the zone of pinching out of its backwater. In the lower section, thequality of water taken in winter is characterized by pronounced inter- and intra-day fluctuations caused by significant changes in waterdischarge rates in the lower pool. At the same time, in the upper section of the reservoir, located in the zone of backwater wedging out,these fluctuations are observed in the warm period, during the formation of vertical stratification of water masses. These phenomenaoccur with a significant decrease in the slopes of the water surface and, accordingly, a decrease in current speeds.

Differences of water chemistry, bird assemblages and nutrient loads introduced by waterbirds into morphologically similar waterbodies

The number and structure of waterbirds is affected by the size of the waterbody, the presence of islands and macrophytes, but also by their trophy status. The aims of the study were to compare nutrients in water, numbers of waterbird assemblages, and the loading of nitrogen and phosphorus introduced by waterbirds in two similar waterbodies with different rates of water discharge. This study was conducted in two eutrophic shallow waterbodies, P1 and P2 in 2016 and 2017. The median concentrations of NO2 - , NO3 - and NH4 + were 4.0 times, 3.2 times, and 1.7 times greater in the P1 than in the P2 location, respectively. Similar proportions of organic matter in sediments were statistically greater in P1. The number of birds was also significantly greater in P1 than in P2. The waterbirds (Anas platyrhynchos, Aythya fuligula, Fulica atra, Phalacrocorax carbo and Chroicocephalus ridibundus) excreted 5.2 times more total phosphorous and 3.3 times more total nitrogen in P1 than in P2. Significant negative correlations were also found between the concentrations of NO3 - and the number of waterbirds in P1.

Investigating the applicability and assumptions of the regression relationship between flow discharge and nitrogen concentrations for load estimation

The regression relationship between water discharge rates and nutrient concentrations can provide a quick and straightforward way to estimate nutrient loads. However, recent studies indicated that the relationship might produce large biases in load estimates and, therefore, may not be applicable in certain types of cases. The goal of this study is to explore the theoretical reasons behind the selective applicability of the regression relationship between flow rates and nitrate + nitrite concentrations. For this study, we examined daily flow and nitrate + nitrite concentration observations made at the outlets of 22 watersheds monitored by the Heidelberg Tributary Loading Program (HTLP). The statistical relationship between the flow rates and concentrations was explored using regression equations offered by the LOAD ESTimator (LOADEST). Results demonstrated that the use of the regression equations provided nitrate + nitrite load estimates at acceptable accuracy levels (NSE≥0.35 and |PBIAS|≤30.0%) in 14 watersheds (64 % of 22 study watersheds). The regression relationships provided highly biased results at eight watersheds (36 %), implying their limited applicability. The heteroscedasticity of the residuals led to the high bias and resulting inaccurate regression, which was commonly found in watersheds where low flow had high nitrate + nitrite concentration variations. Conversely, the regression relationships provided acceptable accuracy for watersheds that had a relatively constant variance of the nitrate + nitrite concentrations. The results indicate that the homoscedasticity of residuals is the key assumption to be satisfied to estimate nitrate + nitrite loads from a statistical regression between flow discharge and nitrate + nitrite concentrations. The transport capacity (capacity-limited) concept implicitly assumed in the regression relationship between flow discharge and nitrate + nitrite concentrations is not always applicable, especially to agricultural areas in which nitrate + nitrite loads are highly variable depending on management practices (supply-limited). The findings suggest that the regression relationship should be carefully applied to areas in which intensive agricultural activities, including crop management and conservation practices, are implemented. Thus, the transport capacity concept is reasonably regarded to contribute to the homoscedasticity of residuals.

Evaluation of double pipe heat exchanger performance with right angle turbulator

In this paper, two horizontal cross-flow pipes were experimentally investigated. Three discharge rates for hot water were used, namely 1.5, 2.5, and 3 liters per minute, while maintaining a 6 liters per minute cold water discharge rate. Comparing the discharge rates in both instances and relying on the hot water discharge rate that results in the biggest heat exchange was done. The first (typical) type involved the analysis of a heat exchanger with two horizontal tubes of convection flow; in this case, there were no additives in the hot pipe, and the best rate of hot water discharge was 1.5 liters per minute. As a result, the optimal Nusselt number was identified. In the second part, right-angle turbulators with dimensions of 1 mm, 5 mm, and 7 mm were added inside the hot pipe to enhance the heat exchange. It was discovered that the Nusselt number is significantly better than the typical situation (without angles). When adding this kind of turbulator, the Nusselt number is enhanced by 28.1%.

Impact of Pipe Length on Discharge and Headloss in PVC Water Pipe Installations

This study was conducted to investigate the implications of pipe length on water discharge and headloss in clean water pipe installations in Klampok hamlet, Indonesia. Three residential houses were selected as research sites, each equipped with a 2-inch diameter PVC type pipe and a water pump with a power of 3.6 housepower. The goal was to measure the water discharge, major and minor headloss, and the flow pattern within these pipe installations. Results revealed a water pump discharge to the reservoir of 0.004 m3/s, while the reservoir water discharge designated to supply residents’ houses was 0.0026 m3/s. Further, the study uncovered that headloss value was inversely proportional to pipe length, with a maximum major headloss value of 1.764 m at 17 m and a minimum of 1.038 m at 10 m, similarly mirrored in minor headloss values. Finally, the flow pattern within the pipe, irrespective of its length, was found to be turbulent, as deduced from the Reynolds number (Re=165,780 > 4,000). These findings underscore the role of pipe length in dictating energy loss and water discharge rates, offering key insights for the design and installation of efficient water supply systems.

Contemporary ice sheet thinning drives subglacial groundwater exfiltration with potential feedbacks on glacier flow.

Observations indicate that groundwater-laden sedimentary aquifers are extensive beneath large portions of the Greenland and Antarctic ice sheets. A reduction in the mechanical loading of aquifers is known to lead to groundwater exfiltration, a discharge of groundwater from the aquifer. Here, we provide a simple expression predicting exfiltration rates under a thinning ice sheet. Using contemporary satellite altimetry observations, we predict that exfiltration rates may reach tens to hundreds of millimeters per year under the fastest thinning parts of the Antarctic Ice Sheet. In parts of West Antarctica, predicted rates of exfiltration would cause the total subglacial water discharge rate to be nearly double what is currently predicted from subglacial basal melting alone. Continued Antarctic Ice Sheet thinning into the future guarantees that the rate and potential importance of exfiltration will only continue to grow. Such an increase in warm, nutrient-laden subglacial water discharge would cause changes in ice sliding, melt of basal ice and marine biological communities.

Designing optimal solar water pumping stations for irrigation of agricultural lands

An investigation into the design of a stand-alone solar water pumping station for supplying rural areas is presented. It includes a study of system components and their modeling. The solar water pumping station comprises a solar panel, DC/DC buck converter, DC motor driving a centrifugal pump, and a reservoir. The fuzzy-based maximum power point tracker is developed to optimize the drive speed and the water discharge rate of the coupled centrifugal pump. These use dN/I, d(dN/dI) use parameters, and a variation of the fill factor∆α as input variables. The proposed solution is based on a judicious fuzzy adjustment of a converter fill factor, which adapts online the load impedance to the solar panel. The simulation results show the effectiveness of the drive system for both transient and steady-state operations. Hence, it is suitable to use this fuzzy logic procedure as a standard optimization algorithm for such solar water pumping stations. The modeling is carried out in MATLAB/Simulink.

Experience in Numerical Hydrodynamic Simulation of Long River Reaches

The article formulates the main requirements to numerical algorithms for hydrodynamic 2D-modeling of long and very long river segments with lengths of up to several thousand kilometers. The main feature is the use of adaptive unstructured mesh along with algorithms that give correct values of water surface elevations on coarse mesh, taking into account abrupt changes of bed elevations. A hydrodynamic model of a segment of the Amur R. with a total length of 3 thous. km is presented, which is based on a numerical solution of two-dimensional shallow-water equations (Saint-Venant) by a new high-accuracy algorithm, taking into account road and protection structures in the floodplain. The stages of model construction and verification are described, and the results of calculations for an extraordinary flood in 2013 and a high flood in 2020 are given. Water levels (with estimates of their errors) and the rates of water discharge at gages are given along with flow fields and the inundation zones of floodplain areas.

Impacts of Reservoir Operation on Hydrodynamic and Thermal Conditions in a Large Deep Reservoir and the Potential Ecological Impacts

Many large-deep reservoirs have been built, are under construction, or are planned in southwestern China, to meet increasingly high energy demands. The construction of dams can significantly alter the natural hydrodynamic and thermal conditions of rivers, thereby, threatening aquatic ecosystems, e.g., fish and algae communities. However, the impacts of large-deep reservoir operations on the hydrodynamic and thermal conditions and their potential influence on aquatic ecosystems have seldom been addressed. In this study, a quasi-3D hydrodynamic model is developed to describe the hydrodynamic and thermal conditions of a large deep reservoir, Nuozhadu, the largest reservoir along the Lancang River. The water temperature and flow velocity after the impoundment of the reservoir are examined. To explore how reservoir operation changes the hydrodynamic and thermal conditions, five groups of reservoir operational scenarios based on different water levels and discharge rates are conducted. Our results indicate that a lower water level combined with a higher discharge rate can increase the flow velocity and decrease the surface water temperature in the reservoir, which may contribute to diminishing the growth of Cyanobacteria. Meanwhile low water levels can also increase the outflow water temperature to protect the downstream fish. Further, the LowLevel and MaxPower schemes were designed to provide ecologically favorable hydrodynamic conditions, and to maximize power generation, respectively. The LowLevel scheme was found to reduce the duration of high surface water temperature (>25°C) by 18 days annually and reduce the outflow temperature by 0.8°C in the fish spawning period, at the expense of a 10% reduction in power generation. This study contributes to a better knowledge of the linkage among hydrodynamic, thermal conditions, and ecological impacts due to reservoir operation, and provides a novel perspective regarding the ecological safety of a large deep reservoir operation.