Water quality models are important tools to support the optimization of aquatic ecosystem rehabilitation programs and assess their efficiency. Basing on the flow conditions of the Daqinghe River Mouth of the Dianchi L...Water quality models are important tools to support the optimization of aquatic ecosystem rehabilitation programs and assess their efficiency. Basing on the flow conditions of the Daqinghe River Mouth of the Dianchi Lake, China, a two-dimensional water quality model was developed in the research. The hydrodynamics module was numerically solved by the alternating direction iteration （ADI） method. The parameters of the water quality module were obtained through the in situ experiments and the laboratory analyses that were conducted from 2006 to 2007. The model was calibrated and verified by the observation data in 2007. Among the four modelled key variables, i.e., water level, COD （in CODcr）, NH4＋-N and PO43-P the minimum value of the coefficient of determination （COD） was 0.69, indicating the model performed reasonably well. The developed model was then applied to simulate the water quality changes at a downstream cross-section assuming that the designed restoration programs were implemented. According to the simulated results, the restoration programs could cut down the loads of COD and PO43-P about 15%. Such a load reduction, unfortunately, would have very little effect on the NH4^＋-N removal. Moreover, the water quality at the outlet cross-section would be still in class V （3838-02）, indicating more measures should be taken to further reduce the loads. The study demonstrated the capability of water quality models to support aquatic ecosystem restorations.展开更多
With the development of industry and agriculture,nitrogen,phosphorus and other nutrients in the Hanshui River greatly increase and eutrophication has become an important threat to the water quality of the Hanshui Rive...With the development of industry and agriculture,nitrogen,phosphorus and other nutrients in the Hanshui River greatly increase and eutrophication has become an important threat to the water quality of the Hanshui River,especially in the middle and lower reaches.The primary objective of this study was to establish the water quality model for the middle and lower reaches of the Hanshui River based on the model of MIKE 11.The main pollutants migration and transformation process could be simulated using the water quality model.The rainfall-runoff model,hy-drodynamic model and water quality model were established using MIKE 11.The pollutants,such as chemical oxygen demand(COD),biochemical oxygen demand(BOD),ammonia nitrogen,nitrate nitrogen,phosphorus,dissolved oxy-gen(DO),were simulated and predicted using the above three models.A set of methods computing non-point source pollution load of the Hanshui River Basin was proposed in this study.The simulated and observed values of COD,BOD5,ammonia,nitrate,DO,and total phosphorus were compared after the parameter calibration of the water quality model.The simulated and observed results match better,thus the model can be used to predict water quality in the fu-ture for the Hanshui River.The pollution trend could be predicted using the water quality model according pollution load generation.It is helpful for government to take effective measures to prevent the water bloom and protect water quality in the river.展开更多
This paper describes research undertaken by the authors to develop an integrated measurement and modeling methodology for water quality management of estuaries. The approach developed utilizes modeling and measurement...This paper describes research undertaken by the authors to develop an integrated measurement and modeling methodology for water quality management of estuaries. The approach developed utilizes modeling and measurement results in a synergistic manner. Modeling results were initially used to inform the field campaign of appropriate sampling locations and times, and field data were used to develop accurate models. Remote sensing techniques were used to capture data for both model development and model validation. Field surveys were undertaken to provide model initial conditions through data assimilation and determine nutrient fluxes into the model domain. From field data, salinity re- lationships were developed with various water quality parameters, and relationships between chlorophyll a concentrations, transparency, and light attenuation were also developed. These relationships proved to be invaluable in model development, particularly in modeling the growth and decay of chlorophyll a. Cork Harbour, an estuary that regularly experiences summer algal blooms due to anthropogenic sources of nutrients, was used as a case study to develop the methodology. The integration of remote sensing, conventional fieldwork, and modeling is one of the novel aspects of this research and the approach developed has widespread applicability.展开更多
In order to establish economic development region at Mawei districtwhich is nearby downstream of Minjiang river and to answer the question of impact of economic development on water quality of Minjiang estuary, the an...In order to establish economic development region at Mawei districtwhich is nearby downstream of Minjiang river and to answer the question of impact of economic development on water quality of Minjiang estuary, the analyses of hydrologic and hydraulic characteristics of Mawei reach of Minjiang tidal river, a two-dimensional mathematical model has been established and simulation of water quality was studied. The results show that the flushing time of a conservative pollutant during dry and raining period are 12 and 7 days respectively from Mawei to Minjiang mouth, the decay rate constants of BOD and NH3-N are 0.1 to 0.4 and 0.18 to 0.45 d-1 respectively. The capacity of dilution and assimilation for pollutants is larger.展开更多
In order to simulate changes in the water quality of the Miyun Reservoir dueto continuous descent of surface water level, a 3-D ecological hydrodynamic model was developedthrough coupling the water quality analysis si...In order to simulate changes in the water quality of the Miyun Reservoir dueto continuous descent of surface water level, a 3-D ecological hydrodynamic model was developedthrough coupling the water quality analysis simulation program (WASP) with the environmental fluiddynamics code (EFDC). The model was then calibrated and verified. Four scenarios (S1, S21, S22 andS23) were simulated using the model. Results show that the water quality of the Miyun Reservoirunder conditions of low surface water level is apparently affected by different amounts of inflowand different total phosphorus (TP) loadings. The chlorophyll-a concentration might exceed 10 μg/Lin many areas of the Miyun Reservoir (This limitative value is seen as a critical value ofeutrophication) when large loadings of TP enter due to the amount of inflow increasing. Results ofscenario S23 indicate that control of TP loadings can decrease chlorophyll-a concentrationeffectively, and the water quality of the Miyun Reservoir will improve or retain its status quo.展开更多
The hydrodynamic circulation within the marine environment is a complex phenomenon, characterized by the interplay of strong tidal forces, atmospheric influences, and bathymetric features. The physical and hydrodynami...The hydrodynamic circulation within the marine environment is a complex phenomenon, characterized by the interplay of strong tidal forces, atmospheric influences, and bathymetric features. The physical and hydrodynamic attributes of this flow play a pivotal role in promoting vertical mixing of seawater masses, thereby facilitating the integration of their physical and chemical parameters, including nutrients and oxygen. Additionally, they are instrumental in governing the dispersion and diffusion of pollutants originating from urban sewage, contributing to the overall water renewal process and environmental quality. This study investigates the potential impact of anticipated increases in average air temperatures on water column stratification in coastal regions susceptible to these dynamic influences. These areas receive treated urban sewage, and the study aims to assess how these temperature changes might influence the dispersion and mixing of pollutant loads present in these coastal waters.展开更多
Lake Fuxian is the largest deep freshwater lake in China. Although its average water quality meets Class I of the China National Water Quality Standard （CNWQS）, i.e., GB3838-2002, monitoring data indicate that the w...Lake Fuxian is the largest deep freshwater lake in China. Although its average water quality meets Class I of the China National Water Quality Standard （CNWQS）, i.e., GB3838-2002, monitoring data indicate that the water quality approaches the Class II threshold in some areas. Thus it is urgent to reduce the watershed load through the total maximum daily load （TMDL） program. A three-dimensional hydrodynamic and water quality model was developed for Lake Fuxian, simulating flow circulation and pollutant fate and transport. The model development process consists of several steps, including grid generation, initial and boundary condition configurations, and model calibration processes. The model accurately reproduced the observed water surface elevation, spatiotemporal variations in temperature, and total nitrogen （TN）, total phosphorus （TP）, and chemical oxygen demand （COD） concentrations, suggesting a reasonable numerical representation of the prototype system for further TMDL analyses. The TMDL was calculated using two interpretations of the water quality standards for Class I of the CNWQS based on the maximum instantaneous surface and annual average surface water concentrations. Analysis of the first scenario indicated that the TN, TP and COD loads should be reduced by 66%, 68% and 57%, respectively. Water quality was the highest priority; however, local economic development and cost feasibility for load reduction can pose significant issues. In the second interpretation, the model results showed that, under the existing conditions, the average water quality meets the Class I standard and therefore load reduction is unnecessary. Future studies are needed to conduct risk and cost assessments for realistic decision-making.展开更多
In sub-tropical coastal waters around Hong Kong, algal blooms and red tides are usually first sighted in the Mirs Bay, in the eastern waters of Hong Kong. A calibrated three-dimensional hydrodynamic model for the Pear...In sub-tropical coastal waters around Hong Kong, algal blooms and red tides are usually first sighted in the Mirs Bay, in the eastern waters of Hong Kong. A calibrated three-dimensional hydrodynamic model for the Pearl River Estuary （Delft3D） has been applied to the study of the physical hydrography of Hong Kong waters and its relationship with algal bloom transport patterns in the dry and wet seasons. The general 3D hydrodynamic circulation and salinity structure in the partially-mixed estuary are presented. Extensive numerical surface drogue tracking experiments are performed for algal blooms that are initiated in the Mirs Bay under different seasonal, wind and tidal conditions. The probability of bloom impact on the Victoria Harbour and nearby urban coastal waters is estimated. The computations show that： i） In the wet season （May - August）, algal blooms initiated in the Mirs Bay will move in a clockwise direction out of the bay, and be transported away from Hong Kong due to SW monsoon winds which drive the SW to NE coastal current; ii） In the dry season （November- April）, algal blooms initiated in the northeast Mirs Bay will move in an anti-clockwise direction and be carried away into southern waters due to the NE to SW coastal current driven by the NE monsoon winds; the bloom typically flows past the east edge of the Victoria Harbeur and nearby waters. Finally, the role of hydrodynamic transport in an important episodic event -- the spring 1998 massive red tide -- is quantitatively examined. It is shown that the strong NE to E wind during late March to early April, coupled with the diurnal tide at the beginning of April, significantly increased the probability of bloom transport into the Port Shelter and East Lamma Channel, resulting in the massive fish kill. The results provide a basis for risk assessment of harmful algal bloom （HAB） impact on urban coastal waters around the Victoria Habour.展开更多
基金supported by the National Hi-Tech Research and Development Program (863) of China (No.2007AA06A405, 2005AA6010100401)
文摘Water quality models are important tools to support the optimization of aquatic ecosystem rehabilitation programs and assess their efficiency. Basing on the flow conditions of the Daqinghe River Mouth of the Dianchi Lake, China, a two-dimensional water quality model was developed in the research. The hydrodynamics module was numerically solved by the alternating direction iteration （ADI） method. The parameters of the water quality module were obtained through the in situ experiments and the laboratory analyses that were conducted from 2006 to 2007. The model was calibrated and verified by the observation data in 2007. Among the four modelled key variables, i.e., water level, COD （in CODcr）, NH4＋-N and PO43-P the minimum value of the coefficient of determination （COD） was 0.69, indicating the model performed reasonably well. The developed model was then applied to simulate the water quality changes at a downstream cross-section assuming that the designed restoration programs were implemented. According to the simulated results, the restoration programs could cut down the loads of COD and PO43-P about 15%. Such a load reduction, unfortunately, would have very little effect on the NH4^＋-N removal. Moreover, the water quality at the outlet cross-section would be still in class V （3838-02）, indicating more measures should be taken to further reduce the loads. The study demonstrated the capability of water quality models to support aquatic ecosystem restorations.
基金Under the auspices of National Science and Technology Research during the 11th Five-Year Plan Period (No.2008BAI62B05)National Natural Science Foundation of China (No. 50879005,51179006)
文摘With the development of industry and agriculture,nitrogen,phosphorus and other nutrients in the Hanshui River greatly increase and eutrophication has become an important threat to the water quality of the Hanshui River,especially in the middle and lower reaches.The primary objective of this study was to establish the water quality model for the middle and lower reaches of the Hanshui River based on the model of MIKE 11.The main pollutants migration and transformation process could be simulated using the water quality model.The rainfall-runoff model,hy-drodynamic model and water quality model were established using MIKE 11.The pollutants,such as chemical oxygen demand(COD),biochemical oxygen demand(BOD),ammonia nitrogen,nitrate nitrogen,phosphorus,dissolved oxy-gen(DO),were simulated and predicted using the above three models.A set of methods computing non-point source pollution load of the Hanshui River Basin was proposed in this study.The simulated and observed values of COD,BOD5,ammonia,nitrate,DO,and total phosphorus were compared after the parameter calibration of the water quality model.The simulated and observed results match better,thus the model can be used to predict water quality in the fu-ture for the Hanshui River.The pollution trend could be predicted using the water quality model according pollution load generation.It is helpful for government to take effective measures to prevent the water bloom and protect water quality in the river.
基金supported by the Irish Environmental Protection Agency under the Environmental Monitoring,R&D Sub-Programme,Operational Programme for Environmental Sciences(Grant No.EPA_97_0151)
文摘This paper describes research undertaken by the authors to develop an integrated measurement and modeling methodology for water quality management of estuaries. The approach developed utilizes modeling and measurement results in a synergistic manner. Modeling results were initially used to inform the field campaign of appropriate sampling locations and times, and field data were used to develop accurate models. Remote sensing techniques were used to capture data for both model development and model validation. Field surveys were undertaken to provide model initial conditions through data assimilation and determine nutrient fluxes into the model domain. From field data, salinity re- lationships were developed with various water quality parameters, and relationships between chlorophyll a concentrations, transparency, and light attenuation were also developed. These relationships proved to be invaluable in model development, particularly in modeling the growth and decay of chlorophyll a. Cork Harbour, an estuary that regularly experiences summer algal blooms due to anthropogenic sources of nutrients, was used as a case study to develop the methodology. The integration of remote sensing, conventional fieldwork, and modeling is one of the novel aspects of this research and the approach developed has widespread applicability.
文摘In order to establish economic development region at Mawei districtwhich is nearby downstream of Minjiang river and to answer the question of impact of economic development on water quality of Minjiang estuary, the analyses of hydrologic and hydraulic characteristics of Mawei reach of Minjiang tidal river, a two-dimensional mathematical model has been established and simulation of water quality was studied. The results show that the flushing time of a conservative pollutant during dry and raining period are 12 and 7 days respectively from Mawei to Minjiang mouth, the decay rate constants of BOD and NH3-N are 0.1 to 0.4 and 0.18 to 0.45 d-1 respectively. The capacity of dilution and assimilation for pollutants is larger.
文摘In order to simulate changes in the water quality of the Miyun Reservoir dueto continuous descent of surface water level, a 3-D ecological hydrodynamic model was developedthrough coupling the water quality analysis simulation program (WASP) with the environmental fluiddynamics code (EFDC). The model was then calibrated and verified. Four scenarios (S1, S21, S22 andS23) were simulated using the model. Results show that the water quality of the Miyun Reservoirunder conditions of low surface water level is apparently affected by different amounts of inflowand different total phosphorus (TP) loadings. The chlorophyll-a concentration might exceed 10 μg/Lin many areas of the Miyun Reservoir (This limitative value is seen as a critical value ofeutrophication) when large loadings of TP enter due to the amount of inflow increasing. Results ofscenario S23 indicate that control of TP loadings can decrease chlorophyll-a concentrationeffectively, and the water quality of the Miyun Reservoir will improve or retain its status quo.
文摘The hydrodynamic circulation within the marine environment is a complex phenomenon, characterized by the interplay of strong tidal forces, atmospheric influences, and bathymetric features. The physical and hydrodynamic attributes of this flow play a pivotal role in promoting vertical mixing of seawater masses, thereby facilitating the integration of their physical and chemical parameters, including nutrients and oxygen. Additionally, they are instrumental in governing the dispersion and diffusion of pollutants originating from urban sewage, contributing to the overall water renewal process and environmental quality. This study investigates the potential impact of anticipated increases in average air temperatures on water column stratification in coastal regions susceptible to these dynamic influences. These areas receive treated urban sewage, and the study aims to assess how these temperature changes might influence the dispersion and mixing of pollutant loads present in these coastal waters.
基金supported by the National Natural Science Foundation of China (No. 41101180)the China National Water Pollution Control Program (No.2010ZX07102-006)
文摘Lake Fuxian is the largest deep freshwater lake in China. Although its average water quality meets Class I of the China National Water Quality Standard （CNWQS）, i.e., GB3838-2002, monitoring data indicate that the water quality approaches the Class II threshold in some areas. Thus it is urgent to reduce the watershed load through the total maximum daily load （TMDL） program. A three-dimensional hydrodynamic and water quality model was developed for Lake Fuxian, simulating flow circulation and pollutant fate and transport. The model development process consists of several steps, including grid generation, initial and boundary condition configurations, and model calibration processes. The model accurately reproduced the observed water surface elevation, spatiotemporal variations in temperature, and total nitrogen （TN）, total phosphorus （TP）, and chemical oxygen demand （COD） concentrations, suggesting a reasonable numerical representation of the prototype system for further TMDL analyses. The TMDL was calculated using two interpretations of the water quality standards for Class I of the CNWQS based on the maximum instantaneous surface and annual average surface water concentrations. Analysis of the first scenario indicated that the TN, TP and COD loads should be reduced by 66%, 68% and 57%, respectively. Water quality was the highest priority; however, local economic development and cost feasibility for load reduction can pose significant issues. In the second interpretation, the model results showed that, under the existing conditions, the average water quality meets the Class I standard and therefore load reduction is unnecessary. Future studies are needed to conduct risk and cost assessments for realistic decision-making.
基金This study was supported by a Hong Kong Research Grants Council Group Research Project (RGC//HKU1/02C) ,and partially by a grantfromthe University Grants Committee of the Hong Kong Special Administrative Region,China(Project No. AoE/P-04/04 and P-04/02) tothe Area of Excellencein Marine Environment Research andInnovativeTechnology (MERIT)
文摘In sub-tropical coastal waters around Hong Kong, algal blooms and red tides are usually first sighted in the Mirs Bay, in the eastern waters of Hong Kong. A calibrated three-dimensional hydrodynamic model for the Pearl River Estuary （Delft3D） has been applied to the study of the physical hydrography of Hong Kong waters and its relationship with algal bloom transport patterns in the dry and wet seasons. The general 3D hydrodynamic circulation and salinity structure in the partially-mixed estuary are presented. Extensive numerical surface drogue tracking experiments are performed for algal blooms that are initiated in the Mirs Bay under different seasonal, wind and tidal conditions. The probability of bloom impact on the Victoria Harbour and nearby urban coastal waters is estimated. The computations show that： i） In the wet season （May - August）, algal blooms initiated in the Mirs Bay will move in a clockwise direction out of the bay, and be transported away from Hong Kong due to SW monsoon winds which drive the SW to NE coastal current; ii） In the dry season （November- April）, algal blooms initiated in the northeast Mirs Bay will move in an anti-clockwise direction and be carried away into southern waters due to the NE to SW coastal current driven by the NE monsoon winds; the bloom typically flows past the east edge of the Victoria Harbeur and nearby waters. Finally, the role of hydrodynamic transport in an important episodic event -- the spring 1998 massive red tide -- is quantitatively examined. It is shown that the strong NE to E wind during late March to early April, coupled with the diurnal tide at the beginning of April, significantly increased the probability of bloom transport into the Port Shelter and East Lamma Channel, resulting in the massive fish kill. The results provide a basis for risk assessment of harmful algal bloom （HAB） impact on urban coastal waters around the Victoria Habour.
