One-dimensional Water Quality Model Research Articles

PHYSICO-CHEMICAL PARAMETERS AND CLIMATE CHANGE IMPACT ON ALGAL GROWTH

Identifying the biological processes that influence algal growth is essential for ecosystem management. Algae are little aquatic plants that exist either as solitary cells or in regions of diverse dimensions. Zooplankton rely on them as a crucial component of the aquatic food chain, since they provide as their primary source of nutrition. Algae, via the process of photosynthesis, produce oxygen that is subsequently released into the water, serving as a vital resource for fish and other aquatic organisms. This work presents a methodology for estimating the biological characteristics of algae, which play a crucial role in the regulation of eutrophication, via the use of modelling and exploration methodologies. The estimation of algae growth and respiration rates was conducted by using a one-dimensional water quality model and two-dimensional regionally distributed water quality data taken from Lower Manair Dam of Karimnagar District, Telangana. A total of 24 algae were detected in the sample. The most abundant types of algae include Green algae, Flagellate algae, Cyanobacteria, and Diatoms. In the summer season, 17 types of algae were found, while in the spring season, 20 types were detected. The estimation of biological characteristics of algae in natural freshwater environments may be achieved by a physico-chemical technique, which offers an alternate option to sampling and in situ testing. KEYWORDS: Algal growth, biological parameters, Lower Manair Dam, eutrophication, in situ testing

Simulation and Application of Water Environment in Highly Urbanized Areas: A Case Study in Taihu Lake Basin

In the wake of frequent and intensive human activities, highly urbanized areas consistently grapple with severe water environmental challenges. It becomes imperative to establish corresponding water environment models for simulating and forecasting regional water quality, addressing the associated environmental risks. The distributed framework water environment modeling system (DF-WEMS) incorporates fundamental principles, including the distributed concept and node concentration mass conservation. It adeptly merges point source and non-point source pollution load models with zero-dimensional, one-dimensional, and two-dimensional water quality models. This integration is specifically tailored for various Hydrological Feature Units (HFUs), encompassing lakes, reservoirs, floodplains, paddy fields, plain rivers, and hydraulic engineering structures. This holistic model enables the simulation and prediction of the water environment conditions within the watershed. In the Taihu Lake basin of China, a highly urbanized region featuring numerous rivers, lakes and gates, the DF-WEMS is meticulously constructed, calibrated, and validated based on 26 key water quality monitoring stations. The results indicate a strong alignment between the simulation of water quality indicators (WQIs) and real-world conditions, demonstrating the model’s reliability. This model proves applicable to the simulation, prediction, planning, and management of the water environment within the highly urbanized watershed.

Random Walk Particle Tracking to Model Dispersion in Steady Laminar and Turbulent Pipe Flow.

To accurately model a two-dimensional solute transport in drinking water pipes and determine the effective dispersion coefficients for one-dimensional water quality models of water distribution systems, a random walk particle tracking approach was developed to analyze the advection and dispersion processes in circular pipes. The approach considers a solute particle's two-dimensional random movement caused by molecular or turbulent diffusion and associated velocity profile, and can simulate any mixing time and accurately model the longitudinal distribution of the solute concentration. For long mixing times, the simulation results agreed with a previous analytically derived solution. For turbulent flow conditions, simulations showed that the longitudinal dispersion of the solute is very sensitive to the utilized cross-sectional velocity profiles. This approach is easy to implement programmatically and unconditionally stable. It can predict the mixing characteristics of a pipe under various initial and boundary conditions.

Pollution source identification and abatement for water quality sections in Huangshui River basin, China

Accurately obtaining the pollution sources and their contribution rates is the basis for refining watershed management. Although many source analysis methods have been proposed, a systematic framework for watershed management is still lacking, including the complete process of pollution source identification to control. We proposed a framework for identification and abatement of pollutants and applied in the Huangshui River Basin. A newer contaminant flux variation method based on a one-dimensional river water quality model was used to calculate the contribution of pollutants. The contributions of various factors to the over-standard parameters of water quality sections at different spatial and temporal scales were calculated. Based on the calculation results, corresponding pollution abatement projects were developed, and the effectiveness of the projects was evaluated through scenario simulation. Our results showed that the large scale livestock and poultry farms and sewage treatment plants were the largest sources of total nitrogen (TP) in Xiaoxia bridge section, with contribution rates of 46.02% and 36.74%, respectively. Additionally, the largest contribution sources of ammonia nitrogen (NH3–N) were sewage treatment plants (36.17%) and industrial sewage (26.33%). Three towns that contributed the most to TP were Lejiawan Town (14.4%), Ganhetan Town (7.3%) and Handong Hui Nationality town (6.6%), while NH3–N mainly from the Lejiawan Town (15.9%), Xinghai Road Sub-district (12.4%) and Mafang Sub-district (9.5%). Further analysis found that point sources in these towns were the main contributor to TP and NH3–N. Accordingly, we developed abatement projects for point sources. Scenario simulation indicated that the TP and NH3–N could be significantly improved by closing down and upgrading relevant sewage treatment plants and building facilities for large scale livestock and poultry farms. The framework adopted in this study can accurately identify pollution sources and evaluate the effectiveness of pollution abatement projects, which is conducive to the refined water environment management.

Operational guidance for aeration and flow augmentation for the Chicago Area Waterway System—A case study

The Chicago Area Waterway System (CAWS) is a 133.9 km branching network of navigable waterways controlled by hydraulic structures, in which the majority of the flow is treated wastewater effluent and there are periods of substantial combined sewer overflows. The CAWS comprises a network of effluent dominated streams. More stringent dissolved oxygen (DO) standards and a reduced flow augmentation allowance have been recently applied to the CAWS. Therefore, a carefully calibrated and verified one-dimensional flow and water quality model was applied to the CAWS to determine emission-based real-time control guidelines for the operation of flow augmentation and aeration stations. The goal of these guidelines was to attain DO standards at least 95% of the time. The “optimal” guidelines were tested for representative normal, dry, and wet years. The finally proposed guidelines were found in the simulations to attain the 95% target for nearly all locations in the CAWS for the three test years. The developed operational guidelines have been applied since 2018 and have shown improved attainment of the DO standards throughout the CAWS while at the same time achieving similar energy use at the aeration stations on the Calumet River system, greatly lowered energy use on the Chicago River system, and greatly lowered discretionary diversion from Lake Michigan, meeting the recently enacted lower amount of allowed annual discretionary diversion. This case study indicates that emission-based real-time control developed from a well calibrated model holds potential to help many receiving water bodies achieve high attainment of water quality standards.

Energy Budget, Water Quality Parameters and Primary Production Modeling in Lake Volvi in Northern Greece

A lake’s water quality and its ecosystem structure are mainly determined by heat storage change through its energy budget, dissolved oxygen, nutrients and primary productivity. A one-dimensional water quality model for lakes was used to estimate temperature, dissolved oxygen, phytoplankton (as chlorophyll-α), and inorganic and organic phosphorus. Evaporation, energy budget and surface water temperature were also computed. The results of the mathematical model simulation are presented and evaluated. Data from Lake Volvi in Central Macedonia (in northern Greece) for three successive years (2013 to 2015) were used to calibrate and recalibrate the model. The model results of water temperature, dissolved oxygen and primary productivity (Chlα) were compared with measurements for the years 2013 to 2015. The comparison showed that the predicted values of these parameters were all in good agreement with the measurements. The simulation results of water quality parameters generally exhibited the same seasonal dynamic and inter-annual variations as the measured data. The simulation results of the model application provided important information on changes in the physical, chemical and biological variables of the lake. The water temperature and heat fluxes at the water–atmosphere interface are crucial variables related to climate changes.

A Developed Method of Water Pollution Control Based on Environmental Capacity and Environmental Flow in Luanhe River Basin

To solve increasingly serious water pollution problems, it is necessary to systematically manage water resources, water environment, and water ecology as elements of a watershed. Comprehensive watershed water pollution control should regard the basin as a whole, respect the natural laws of the river and lake system, and focus on the protection and restoration of its natural ecological environment so that the comprehensive ecological service functions of rivers and lakes can be fully realized. Based on the concepts of environmental capacity (EC) and environmental flow (EF), this study established watershed water pollution control scheme prediction and evaluation methods to explore the changes in the water environment and water ecology in the basin under different water pollution control schemes. The MIKE11 model was used to construct a hydrologic and water quality model of the study area, the one-dimensional water quality model was used to calculate the water environmental capacity, and the Tennant method was used to evaluate the environmental flow. In this study, the method was applied to the Luanhe River Basin of Chengde, Hebei Province, China. It simulated the concentration changes of four pollutants—namely, NH3-N, COD, TN, and TP—under eight different water pollution control schemes, and the responses of EC and EF were compared and analyzed. Some conclusions are as follows: (1) Reducing point source pollution has the most obvious effect on water pollution prevention, especially on NH3-N and COD, while reducing nonpoint source pollution is weaker and the effect of increasing upstream water is the weakest. (2) The increase in up-stream water inflow and reducing point source pollution can greatly increase the EC of NH3-N and COD. The EC of TN can be greatly increased by reducing point source pollution, and the EC of TP can be greatly increased by reducing nonpoint source pollution. (3) The increase in upstream water inflow can improve the EF level to a certain extent. This method can also be applied to other similar river basins, providing valuable suggestions for rationally formulating water environmental management strategies and for promoting the sustainable development of the ecological environment and social economy in the river basin.

Crop pattern optimization for the coordination between economy and environment considering hydrological uncertainty

With the rapid growth of population and economy, shortage and mismatch of land and water resources have deepened the need for cropping pattern optimization. In the context of the sustainable development of agriculture, cropping pattern optimization should not only pursue economic benefits, but the consequent environmental effects also deserve equal attention. Meanwhile, climate change increases the complexity of balancing conflicts of economic-environmental system by cropping pattern optimization. Therefore, this paper builds a multi-objective programming model for Economic-Environmental Synergistic Optimization for Cropping Pattern under Climate Change (EESO-CP-CC) model, with the goals of economic benefit increment and environmental pollutants emission reduction. The EESO-CP-CC model couples a non-point source pollution input-output model, a one-dimensional water quality model and an economic benefit function into an integrated framework. Fuzzy method was used to solve the optimization model, and the stochastic uncertainty of water supply under climate change was quantified by the integration of Bayesian approach and interval linear regression. The model was applied to Jinxi Irrigation District (JXID) in Heilongjiang Province, northeast of China. Results show that by adjusting the acreage of rice, corn and soybean, the harmony degree of economy-society-environment system increased by 10.7% compared to the current situation, indicating that the model tends to achieve the best possible economic benefits while ensuring the environmental effects. Compared with actual cropping pattern, the pollutants emissions reduced by 24.7% and 3% from corn and soybean, respectively. However, this led to a decrease of economic benefit by 8% in exchange, showing the trade-off between environmental pollution reduction and economic benefits improvement. The output coefficients of nitrogen and phosphorus pollutants were optimized, with the optimal output reducing by 20% compared to the standard. Cropping pattern and water resources allocation vary with different climate change conditions, however, the amplitude of variation is modest, indicating that the model can cope well with the changing environment. The developed model can help achieve synergistic development of economic benefits and environmental effects, and thus promote sustainable development of irrigation areas, and improve the coping capacity of agricultural water and land under climate change, by cropping pattern optimization and planning.

Simulating Nutrients and Phytoplankton Dynamics in Lakes: Model Development and Applications

Due to eutrophication, many lakes require periodic management and restoration, which becomes unpredictable due to internal nutrient loading. To provide better lake management and restoration strategies, a deterministic, one-dimensional water quality model MINLAKE2020 was modified from daily MINLAKE2012 by incorporating chlorophyll-a, nutrients, and biochemical oxygen demand models into the regional year-around temperature and dissolved oxygen (DO) model. MINLAKE2020 was applied to six lakes (varying depth and trophic status) in Minnesota focusing on studying the internal nutrient dynamics. The average root-mean-square errors (RMSEs) of simulated water temperature and DO in six lakes are 1.51 °C and 2.33 mg/L, respectively, when compared with profile data over 2–4 years. The average RMSE of DO simulation decreased by 24.2% when compared to the MINLAKE2012 model. The internal nutrient dynamics was studied by analyzing time series of phosphorus, chlorophyll-a, and DO over several years and by performing a sensitivity analysis of model parameters. A long-term simulation (20 years) of Lake Elmo shows that the simulated phosphorus release from sediment under the anoxic condition results in surface phosphorus increase, which matches with the observed trends. An average internal phosphorus loading increase of 92.3 kg/year increased the average daily phosphorus concentration by 0.0087 mg/L.

Simulating Diurnal Variations of Water Temperature and Dissolved Oxygen in Shallow Minnesota Lakes

In shallow lakes, water quality is mostly affected by weather conditions and some ecological processes which vary throughout the day. To understand and model diurnal-nocturnal variations, a deterministic, one-dimensional hourly lake water quality model MINLAKE2018 was modified from daily MINLAKE2012, and applied to five shallow lakes in Minnesota to simulate water temperature and dissolved oxygen (DO) over multiple years. A maximum diurnal water temperature variation of 11.40 °C and DO variation of 5.63 mg/L were simulated. The root-mean-square errors (RMSEs) of simulated hourly surface temperatures in five lakes range from 1.19 to 1.95 °C when compared with hourly data over 4–8 years. The RMSEs of temperature and DO simulations from MINLAKE2018 decreased by 17.3% and 18.2%, respectively, and Nash-Sutcliffe efficiency increased by 10.3% and 66.7%, respectively; indicating the hourly model performs better in comparison to daily MINLAKE2012. The hourly model uses variable hourly wind speeds to determine the turbulent diffusion coefficient in the epilimnion and produces more hours of temperature and DO stratification including stratification that lasted several hours on some of the days. The hourly model includes direct solar radiation heating to the bottom sediment that decreases magnitude of heat flux from or to the sediment.

Study on effect of different reservoir water diversion modes on river water quality improvement

Urban river water pollution is a serious environmental issue and tends to become worse. One of the key measures to improve urban river water quality is to divert water from upstream reservoir to downstream river course to flush pollutant. In this paper, a one-dimensional hydrodynamic and water quality model of Hun River network was developed based on HEC-RAS model. Different reservoir water diversion modes for sewage discharge were simulated and their effect on the water quality improvement of downstream river course was analysed. The results show that under different diversion flow rates, the larger the diversion flow rate, the better the effect on water quality improvement, and that when total water diversion volume is fixed, the effect of long-term diversion with a low flow rate is better than that of short-term diversion with a high flow rate on downstream water quality improvement. The research results can provide scientific support for optimization of the operation of water diversion from reservoir for sewage discharge.

Experimental and simulation studies on the attenuation coefficients of organic pollutants in “Han River and Three Tributaries” basin, China

In order to study the attenuation mechanism and spatial and temporal evolution of organic pollutants in “Han River and Three Tributaries” basin, laboratory experiments were conducted, and a novel COD attenuation coefficient model was proposed. The main environmental factors affecting COD attenuation were identified. On this basis, the attenuation term of the one-dimensional water quality model is modified, and the spatial and temporal distribution characteristics of COD in Hanbei River are simulated and analyzed using the modified water quality model. The results show that: (1) the attenuation process of COD in Hanbei River is basically in accordance with the first-order reaction kinetics, and biodegradation accounts for a large proportion of the whole attenuation process. Within a certain range, the increase of flow velocity, water temperature and sand content promoted COD attenuation, and the effect of sediment particle size on COD attenuation in Hanbei River was not obvious; (2) based on the experimental results, a model for calculating the attenuation coefficient of pollutants is derived. A time varying attenuation coefficient can be calculated, which can realistically reflect the attenuation process and the distribution pattern along the river under the changing environment; (3) Model simulations determined that the COD attenuation coefficient of Hanbei River ranged from 0.03 to 0.19. The research results of this paper provide a scientific and theoretical method to accurately determine the attenuation coefficient of pollutants. It also provides scientific support for determining the ecological water demand of typical rivers and lakes similar to “Han River and Three Tributaries” and the scale of water diversion for Interconnected River System Network.

Evaluation of the effect of water diversion on improving water environment in plain river network under the multi-objective optimization

引调水是改善平原河网地区水环境的重要方法之一，通过构建太湖流域走马塘东南片平原河网区一维水动力水质数学模型，研究不同引调水方案对区域水环境改善效果，确定引调水过程中的异质性因子.从决策目标、水质指标、空间指标3个层面综合考虑，构建环境效益与经济效益结合的多目标函数及评价体系，对引调水方案进行评估优选.结果表明：引调水流量较大时，能够在一定程度上改善区域水环境状况，规划方案下引调水5 d后，高锰酸盐指数、氨氮、总磷的平均改善率分别为30.7%、22.2%、26.4%；引调水时，区域河网中不同空间点位、不同水质指标之间的水质改善过程与效果都存在一定异质性；引调水水量、调度模式及污染源分布都会对调水后的河网区水质产生差异性影响；本研究建立的多目标评价体系较现有方法能够有效涵盖引调水中存在的异质性因子，从多个目标层面优选引调水方案，实现水量水质综合优化调控，为平原河网地区水环境长效管理与科学决策提供理论参考.;Water diversion is a significant method to improve the water environment in the plain river network area. Through building up the one-dimensional hydrodynamic and water quality model of the plain river network area of southeast Zoumatang of Taihu Basin, the effect on water environment of different water diversion schemes was simulated, and the heterogeneous factors in the process were determined. A multi-objective function and evaluation system combining environmental benefits and economic benefits were constructed from three aspects, including decision-making, water quality indexes and spatial indexes, and the water diversion schemes were evaluated and optimized. The results show that: (1) With a larger flow, water diversion can improve the regional water environment to some extent. After 5 days of water diversion under the planning schemes, the average improvement rates of COD_Mn, ammonia nitrogen and total phosphorus were 30.7%, 22.2% and 26.4%, respectively. (2) Heterogeneity existed in the process and effect of water quality improvement in different spatial points and water quality indexes in the river network during water diversion. (3) The water quantity and dispatching mode of water diversion as well as distribution of pollutants all have different effects on the water quality in the river network. (4) Compared with the existing method, the multi-objective evaluation system of water diversion established in this research can effectively cover the heterogenous factors and evaluate and optimize different water diversion schemes from multiple objectives, therefore can achieve comprehensive optimization and control of water quantity and quality, and provide theoretical reference for long-term management and scientific decision-making of water environment in the plain river network area.

Impacts of Sea Level Rise on Seawater Intrusion in Cubatão River, Brazil

Estuarine systems are very sensitive environments to sea level rise as a consequence of climate changes, which can enhance seawater intrusion and affect multiple water uses. The seawater intrusion under sea level scenarios in an estuarine river by applying the one-dimensional hydrodynamic and water quality model HEC-RAS 5.0.5 was studied. The study was carried out at the estuarine reach of Cubatao River, in Sao Paulo, Brazil. Considering sea level rise scenarios of ΔH = 0.25 m, 0.50 m, and 1.0 m combined with constant freshwater discharge conditions for Cubatao River (16 m3/s, mean annual discharge and 8 m3/s, dry season discharge), the model results showed that seawater intrusion moves significantly upstream the river in all cases and the maximum seawater intrusion length may reach 10 km in the worst scenario (ΔH = 1.0 m and 8 m3/s freshwater discharge), 70% higher than the current sea level and the mean discharge. At the local water abstraction point for urban supply, salinity concentration may reach 12 g/kg, making conventional water treatment unfeasible. Sea level rise may threaten water supply facilities and require water resource management solutions, such as water abstraction restricted times when salinity concentration is low; higher freshwater reservation; new water abstraction locations, farther the present ones; or higher water discharges in Cubatao River from a local hydroelectric power plant, which can cause water resource management conflicts.

Spatial-temporal characteristics of nitrogen degradation in typical Rivers of Taihu Lake Basin, China

In this study, we focus on the measurement of different nitrogen (N) forms and investigate the spatial-temporal variability of degradation coefficient in river channels. We aim to provide a new approach of deriving in-situ degradation coefficients of different N forms, and highlight factors that determine the spatial-temporal variability of degradation coefficients. Our results are based on a two-year field survey in 34 channels around the Taihu Lake Basin, eastern China. The derived degradation coefficients of different N forms based our newly-developed experimental device are: degradation coefficients of TN, NH4+-N and NO3-N range from 0.006–0.449 d−1, 0.022–1.175 d−1 and -0.096–2.402 d−1, respectively. The degradation coefficients of N show strong dependence on N concentration and water temperature. The seasonal difference of water temperature and N concentration leads to spatial-temporal variability of degradation coefficients. The derived degradation coefficients of N are further verified through one-dimensional water quality model simulations. The degradation coefficient obtained in this study and the influencing factors of its spatial-temporal variability provide invaluable reference for studies in aquatic environment.

Analysis of the Water Environmental Capacity of Zhongba-Nyingchi Section of the Yarlung Tsangpo River

The Yarlung Tsangpo River, the longest river in Tibet, houses most of the population and economy in Tibet Autonomous province. Under the rapid development of economy and society in Tibet, the pollution in the Yarlung Tsangpo River basin has rapidly increased. Evaluating water quality and water environmental capacity is needed for water resource management in Tibet. This study used a single factor evaluation method to evaluate water quality of the Zhongba-Nyingchi section of the Yarlung Tsangpo River based on measured data of CODCr, NH3-N and TP in the study area. Based on these data, determinations of ideal water environmental capacity, emissions of pollutants and remaining water environmental capacity of the study area were made by a one-dimensional steady water quality model under either section-head control or cross-section control. The data indicate that most of the monitoring sections in the study area experienced good water quality. The three pollutants all had large remaining water environmental capacity generally, but TP exceeded state levels in the two upstream functional areas, and levels above state standards of CODCr and TP were found in several calculation cells of the two downstream functional areas. Therefore, emissions of pollutants need to be reduced to protect the water environment quality of the Yarlung Tsangpo River.

Assessment of Water Quality Profile Using Numerical Modeling Approach in Major Climate Classes of Asia.

A river water quality spatial profile has a diverse pattern of variation over different climatic regions. To comprehend this phenomenon, our study evaluated the spatial scale variation of the Water Quality Index (WQI). The study was carried out over four main climatic classes in Asia based on the Koppen-Geiger climate classification system: tropical, temperate, cold, and arid. The one-dimensional surface water quality model, QUAL2Kw was selected and compared for water quality simulations. Calibration and validation were separately performed for the model predictions over different climate classes. The accuracy of the water quality model was assessed using different statistical analyses. The spatial profile of WQI was calculated using model predictions based on dissolved oxygen (DO), biological oxygen demand (BOD), nitrate (NO3), and pH. The results showed that there is a smaller longitudinal variation of WQI in the cold climatic regions than other regions, which does not change the status of WQI. Streams from arid, temperate, and tropical climatic regions show a decreasing trend of DO with respect to the longitudinal profiles of main river flows. Since this study found that each climate zone has the different impact on DO dynamics such as reaeration rate, reoxygenation, and oxygen solubility. The outcomes obtained in this study are expected to provide the impetus for developing a strategy for the viable improvement of the water environment.

Evolutionary polynomial regression approach to predict longitudinal dispersion coefficient in rivers

The fate of pollutants in rivers is mainly affected by the longitudinal dispersion coefficient (Kx). Thus, improved Kx estimation could greatly enhance the water quality management of rivers. In this regard, evolutionary polynomial regression (EPR) was used to accurately predict Kx in rivers as a function of flow depth, channel width, and average and shear velocities. The predicted Kx by EPR modelling was compared with results obtained by more conventional Kx estimation formulas. Initial data analyses using general linear models of variance revealed that all input variables were statistically significant for Kx estimation. The calibrated EPR model showed good performance with coefficient of determination and root mean square error of 0.82 and 79 m2/s, respectively. This is better that other more conventional estimation methods. Application of sensitivity analysis for the EPR model indicated that channel width, average velocity, shear velocity, and flow depth were the main variables in descending order that affected Kx variability. The introduced EPR estimation model for Kx can be incorporated in one-dimensional water quality models for improved simulation of solute concentration in natural rivers. (Less)

An Integrated Method for Accounting for Water Environmental Capacity of the River–Reservoir Combination System

The security of drinking water is a serious issue in China and worldwide. As the backup source of drinking water for the Changde City in China, the Huangshi Reservoir suffers from the threat of eutrophication due to the water quality of the reservoir ecosystem being affected by the tributaries that carry Non-Point Source (NPS) pollutants. The calculation of the water environmental capacity (WEC) can provide a scientific basis for water pollution control, which refers to the maximum amount of pollutants that the water can accommodate. In this paper, according to the hydrological characteristics of the river–reservoir combination system, a one-dimensional (1-D) water quality model and the Environmental Fluid Dynamics Code (EFDC) model were chosen to calculate the water environmental capacity of each functional zone in this basin. The quantity control of pollution from the tributaries was conducted based on the combined results of the water environmental capacity calculation from the EFDC model and a one-dimensional (1-D) river water quality model. The results show that total water environmental capacity of the tributaries included a chemical oxygen demand (COD) of 421.97 tons; ammonia nitrogen (NH3-N) of 40.99 tons; total nitrogen (TN) of 35.94 tons; and total phosphorus (TP) of 9.54 tons. The water environmental capacity of the Huangshi Reservoir region accounts for more than 93% of the total capacity. The reduction targets of the major pollutants in the Huangshi Reservoir and its four major input rivers, which are, namely, the Bamao River, the Longtan River, the Fanjiafang River, and the Dongtan River, have been determined to achieve the water quality objectives for the reservoir in 2020 and 2025. The results will be helpful for the local water quality management and will provide a valuable example for other similar water source reservoirs.

Water Flow Regulation and Scheme Optimization in the Haihe River

Abstract To improve water quality in the Haihe River, 6 cycle routes and 16 water diversion schemes were simulated, and their influence on water quality was analyzed. First, a one-dimensional hydrodynamic and water quality model of the Haihe River was established. Then, according to an orthogonal experiment, 16 cycle schemes were proposed, and an orthogonal experimental table, including 3 factors and 4 levels, was used to optimize the 16 schemes. Average pollutant concentration from Sanchakou to the Erdao Sluice served as the index for orthogonal experiments. Index values were obtained from the model and the influence of three factors on chemical oxygen demand, total nitrogen, total phosphorus, and nitrogen ammonia was evaluated by range analysis. In addition, optimal schemes to reduce pollutants in each route were also obtained. After comparing the simulated results of the optimal schemes in each route, an optimal route was obtained. A combination of the one-dimensional hydrodynamic and water quality mod...