Numerical simulation of pollutant diffusion and decay process after a water pollution incident in the Three Gorges Reservoir

We established a hydrodynamic model to simulate the pollutant transport and decay process in the case of a pollution incident in the sections of the Yangtze and the Jialing passing through the city area of Chongqing. The Boussinesq assumptions and the Navier-Stokes equations of incompressible fluid were applied to setting up the pollutant diffusion equations and the equations for the decay process. E. colt was taken as the example pollutant, and chloride dosage, light, temperature and ultraviolet intensity were considered in the equations for bacterial decay process. The calculated values of the fluid velocities in the two rivers agree well with corresponding measured results, indicating an ideal accuracy of the model. In simulation, the concentration of E. colt in water was assumed to be zero before the accident. The and 1.75 m/s for the Yangtze flow, and the downriver boundary was upriver boundary velocity was -1.35 m/s for the Jialing flow water depth set at 0. Simulation results show that the bacteria are transported downstream along the riverbank. A long and narrow pollutant belt develops at 12 h after the start of the accident ascribed to the quick longitudinal transfer. After the pollution sources are cut off, the pollutant concentration decreases slowly, mostly by advection and diffusion, suggesting inadequate self-purification ability of the rivers and the necessity of effective decontaminating measures in the case of a pollution incident, The model can be a useful tool for understanding the polluting situations of an improper discharge incident and evaluating the effects of decontaminating measures for the water body of the Three Gorges Reservoir.

Water pollution control planning for the Taizi River watershed

Water pollution control planning for the Taizi River watershed,a typical Chinese case study,is presented in this paper. Based on comprehensive analysis.water quality in the watershed was assessed and predicated;water quality models for the river and reservoir were built;and function of water bodies and environmental assimilative capacity were determined ;and then the planning for industrial pollution sources and concentrated sewage treatment were made respectively.

Study on Water Pollution Control of Huaihe River and Countermeasures

Huaihe River is one of three major rivers in China with a large population and developed economy. By the 1970s, the water quality of Huaihe River was deteriorating daily and more than a hundred serious pollution accidents of water quality happened and caused the inestimable losses in the production, life and health of residents along the river and terribly damaged the ecological system of the river. Through the continuous large-scale treatment for more than 10 years, the deterioration of water quality in Huaihe River has been basically inhibited. Nevertheless, the water pollution in Huaihe River is, on the whole, still very serious for many reasons, including special climatic conditions, terrible lack of water resource, obsolete industrial structure and unsound management system for the river, etc. This essay deeply analyzes the rea- sons why the water pollution of Huaihe River is ＂chronic＂ and puts forward the corresponding countermeasures for how to continuously improve the water quality of the river. In the end, this essay argues that it still takes 30-50 years or even a longer period, even if every measures are implemented smoothly and strictly, to actually make the water of Huaihe River clean and gradually restore its normal ecological and environmental functions.

Research on the Applications of Cyclic Water Quality Model and Simulated Annealing Algorithm for Water Pollution Control and Planning

With the progress of computer technology, water pollution control and planning has been a hot topic in the scientific community. This paper discusses corresponding research on the applications of cyclic water quality model and simulated annealing algorithm for water pollution control and planning. Environmental engineering education has been the focus of much attention in recent years. Teaching methods of water pollution control and sustainable teaching innovation and creation was explored by many scholars, and the majority of workers engaged in teaching the course. The simulation result proves the effectiveness of the method. We plan to conduct more research in the future research to obtain better research result.

Implications of Declining Ground Water and Water Quality in the Greater Okefenokee Swamp Basin for Survival and Recovery of Federally Endangered and Threatened Marine and Aquatic Species and Critical Habitat in the US Southeastern Coastal Plain Ecoregion—Part 2

The Floridan aquifer system underlies the United States (US) Southeastern Coastal Plain Physiographic Region. Anthropogenic groundwater declines in that regional karst aquifer system, via semi-confining zones, have been documented in published literature for decades. These anthropogenic groundwater declines reduce surfacewater levels and flows, which increases saltwater intrusion and alters the physical, chemical, and biological integrity of the nation’s waters, in violation of the US Clean Water Act (CWA) of 1972. Historic groundwater declines from mining and other anthropogenic groundwater withdrawals from this regional karst aquifer system already threaten the survival and recovery of marine and aquatic federally endangered and threatened species, as well as existing and proposed critical habitat for those species within the Southeastern Coastal Plain Ecoregion. Examples of marine and aquatic species and their designated critical habitat adversely affected by groundwater declines in the Greater Okefenokee Swamp Basin of this ecoregion include the federally endangered south Atlantic Distinct Population Segments (DPS) of the Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus), shortnose sturgeon (Acipenser brevirostrum), and oval pigtoe mussel (Pleurobema pyriforme), as well as the federally threatened Gulf subspecies of the Atlantic sturgeon (Acipenser oxyrinchus desotoi) and Suwannee moccasinshell (Medionidus walkeri). In 2020, rules were adopted by two federal agencies allowing significant further degradation of the physical, chemical, and biological integrity of the nation’s waters that are essential for maintaining federally listed species and their habitat in this Ecoregion. The US Fish and Wildlife Service (USFWS) has acknowledged the harm to these species and critical habitat from mining and additional groundwater alterations, but no comprehensive Areawide Environmental Impact Statement (AEIS), similar to the AEIS required for mining within the Peace River Basin, has been conducted for any of the numerous mining projects that are expanding and proposed within the Greater Okefenokee Swamp Basin to evaluate all indirect and cumulative adverse impacts to all federally listed species.

STUDY ON THE POLLUTION OF URBAN SCENIC WATER BODY BY MUNICIPAL DRAINAGE IN FLOOD SEASON AND ITS CONTROL PLANNING

In this article, based on river quality simulation and system optimization, a water quality model was established for scenic river after rainfall discharge in flood season, with the target of making water pollutants meet the standard in priority and saving expenditure on pollution control. With the principle of reducing sewage from combined sewage pumping station and heavily polluted initial rainwater, a mathematical multiobjective planning model was constructed for rain sewage pollution control in flood season, and one scenic river in a northern city was taken for simulation example. The results show that： the optimization result meets the requirements of planning, among which, sewage reduction from the combined pumping station accounts for 17.38% in the total reduction of rain sewage, and the reduction in the heavily polluted rain water accounts for 77.24% in the total reduction of rainwater pumping station. The planning scheme can provide theoretical basis for pollution control of scenic river in flood season, and for rational reconstruction and layout of outfalls along two banks of the river.

System engineering for water pollution control at the watershed level in China

The present water pollution situation at watershed level in China has been systematically analyzed.The causes of water pollution are attributed to the extensive economic developmental pattern,poor wastewater treatment,and a lack of nonpoint pollution control.The problems of water pollution control at watershed level include a lack of thought and approach,developmental delay in the environmental standard system,an inadequate monitoring ability,and an inefficient implementation of laws and regulations.From 2006 to 2020,water pollution control and governance will be a national key specific project of science and technology in China.The strategies of this project include establishing a water pollution control system at watershed level,orienting a healthy aquatic ecosystem,conducting risk management,and using comprehensive methods.The goal is to establish and complete a technological system of pollution control and management in three five-year phases.The main tasks are to develop common technologies,management systems,and mechanisms for lake eutrophication control,river pollution control,urban water environmental pollution control,potable water safety,and water environmental management.The bottlenecks of water pollution control and management in China could be systematically removed,and the demonstration of the system engineering approach will be conducted at selected key watersheds.

Post-evaluation of a water pollution control plan： methodology and case study

China has developed more than 20 water pollution control plans for river basins （RBWPs） since 1996. However, the implementation has generally lagged. This paper proposes a three-step, post-evaluation methodology to analyze the implementation result of a RBWP and its influential factors. First, a multi-attribute evaluation method based on an index system is established to score the enforcement results of a RBWP. Indicators measure how well a RBWP has achieved its objectives, which include water quality compliance, pollution load control, project construction, financial inputs, and related management requirements. Second, an interpretive structural model is used to detect the significant factors that affect RBWP implementation. This model can effectively analyze the cause-effect chain and hierarchical relationship among variables. Five groups of factors were identified, namely, plan preparation, water resource endowment, policy, institution, and management. Both qualitative and quantitative methods are employed in the third step to evaluate the extent to which these factors have influenced the execution result of a RBWP, including pre-post contrast, scenario analysis, and correlation analysis. This research then post-evaluated the implementation of the Huai River Basin water pollution control plans （H-RBWPs） over a period of 10 years as a case study. Results showed that the implementation of the H-RBWPs was unsatisfactory during 2001–2005, although it improved during 2006–2010. The poor execution of these plans was partially caused by the underestimation of regional economic development in combination with ineffective industrial structure adjustment policies. Therefore, this case study demonstrates the feasibility and flexibility of the proposed post-evaluation methodology.

Machine learning parallel system for integrated process-model calibration and accuracy enhancement in sewer-river system

The process-based water system models have been transitioning from single-functional to integrated multi-objective and multi-functional since the worldwide digital upgrade of urban water system management.The proliferation of model complexity results in more significant uncertainty and computational requirements.However,conventional model calibration methods are insufficient in dealing with extensive computational time and limited monitoring samples.Here we introduce a novel machine learning system designed to expedite parameter optimization with limited data and boost efficiency in parameter search.MLPS,termed the machine learning parallel system for fast parameter search of integrated process-based models,aims to enhance both the performance and efficiency of the integrated model by ensuring its comprehensiveness,accuracy,and stability.MLPS was constructed upon the concept of model surrogation t algorithm optimization using Ant Colony Optimization(ACO)coupled with Long Short-Term Memory(LSTM).The optimization results of the Integrated sewer network and urban river model demonstrate that the average relative percentage difference of the predicted river pollutant concentrations increases from 1.1 to 6.0,and the average absolute percent bias decreases from 124.3%to 8.8%.The model outputs closely align with the monitoring data,and parameter calibration time is reduced by 89.94%.MLPS enables the efficient optimization of integrated process-based models,facilitating the application of highly precise complex models in environmental management.The design of MLPS also presents valuable insights for optimizing complex models in other fields.