Dynamic Water Quality Model Research Articles

Simulation Study on Water Quality of Paddy Field Ditches Considering the Effects of Rainfall and Sediment Release

As the main channel for the drainage of paddy fields, the water quality of canals directly affects the water quality of surrounding water bodies. Factors such as rainfall and the release of accumulated pollutants from the sediment of the canals have a direct impact on the water quality of drainage ditches. Based on the measured hydrological and water quality data, a dynamic water quality model was built to simulate the runoff and water quality changes in a paddy field for different return periods (1, 2, 5, 10, 20, and 50 years), and to consider the effects of released drainage sediment on the water quality of the paddy field. The change in water quality in paddy fields and ditches in different periods was studied. The simulation results showed that under different return periods, the total nitrogen concentration and total phosphorus concentration in the water of the paddy field and ditch increased first, and then decreased with time in June and July–September, while the pollutant concentration remained basically stable after the end of rainfall. With the increase in return period, the total nitrogen concentration and total phosphorus concentration decreased gradually. The release of nitrogen and phosphorus from the sediment of ditches resulted in an increase in the total nitrogen concentration and total phosphorus concentration in the ditches, and an increase in the pollution load. Under the influence of rainfall and fertilizer, the total nitrogen concentration and total phosphorus concentration in paddy ditch drainage were generally higher and more polluted in June than in July–September, and under the influence of released sediment, the ditch drainage was most polluted in June when the return period was one year, with the total nitrogen concentration and total phosphorus concentration at the outlet of the paddy ditch reaching 21.63 mg/L and 0.88 mg/L, respectively. The research results can provide a theoretical basis and basic support for the interception and treatment of non-point source pollution in farmland.

Evaluation of different management scenarios for trout farm effluents using dynamic water quality modeling

Trout farm effluents are among the important sources of water pollution by nutrients, organics, and suspended solids. This research study was conducted to investigate and manage the impacts of trout farm effluents on Esen Stream water quality, which is located at the southwest of Turkey. A water quality monitoring program was conducted for a period of 1year at 21 stations to determine river hydraulics and water quality characteristics. Monthly water quality analyses were conducted for inflow and outflow of a number of selected farms to determine their characteristics and contribution to water pollution. About 1460 t of suspended solids, 230 t of nitrogen, and 46 t of phosphorus were annually discharged into Esen Stream from the farms. A dynamic water quality simulation model developed by the US-Environmental Protection Agency, WASP8, was applied to Esen Stream to predict and manage pollution from trout farms and the tributaries. The calibrated and verified model was used to evaluate the impacts of different management scenarios on stream water quality. Solid removal with a rotating micro-screen, establishment of a partially recirculated system and increasing production capacities of farms were among the simulated scenarios. The best management practice was the combined application of solids removal and reuse of treated farm effluents in a partially recirculated system, which provided significant improvements in the receiving stream water quality. This study showed that dynamic water quality models are powerful tools for basin-scale management of land-based aquaculture for capacity planning, assimilation capacity estimation, sustainable operation, and environmental impact assessment.

An Integrated Water Quality Model to Support Multiscale Decisions in a Highly Altered Catchment

Decision-making in highly altered catchments occurs at different temporal and spatial scales, requiring integration of various datasets and models. This paper introduces two of the components of an environmental multiscale decision support system (EMDSS) for highly altered catchments, designed to make decisions at different time scales. First, an integrated dynamic flow and water quality model is proposed to analyze the river system, including wastewater discharges and water intakes. This integrated model is capable of representing unsteady flow conditions, allowing analysis at different time scales. Second, three postprocessing tools are presented to support short- (hours to days), medium- (days to months), and long- (years to decades) term operational, management, and planning decisions. The water quality component of the model can represent conventional and toxic determinands to simultaneously analyze domestic and industrial pollution throughout a river system. The first postprocessing tool of the EMDSS is useful in defining concentration limits for wastewater discharges for different water users downstream. The second tool allows the assessment of river water quantity and quality to determine water availability for intake extensions and medium-term wastewater flow augmentation. The third makes it possible to simulate and perform effective operational reservoir releases to improve water quality in the river during short-term pollution incidents. The proposed integrated model and postprocessing tools are applied in the upper Bogotá River stretch in Colombia, one of the most altered catchments and polluted rivers in the world. The results obtained illustrate the utility of the proposed EMDSS for river management and decision making regarding water quality at different time scales.

Large-Scale Hydrological and Sediment Modeling in Nested Domains under Current and Changing Climate

AbstractContinental and global dynamic hydrological models have emerged recently as tools for large-scale analyses. One such tool is a dynamic process-based rainfall-runoff and water quality model ...

Are our dynamic water quality models too complex? A comparison of a new parsimonious phosphorus model, SimplyP, and INCA‐P

AbstractCatchment‐scale water quality models are increasingly popular tools for exploring the potential effects of land management, land use change and climate change on water quality. However, the dynamic, catchment‐scale nutrient models in common usage are complex, with many uncertain parameters requiring calibration, limiting their usability and robustness. A key question is whether this complexity is justified. To explore this, we developed a parsimonious phosphorus model, SimplyP, incorporating a rainfall‐runoff model and a biogeochemical model able to simulate daily streamflow, suspended sediment, and particulate and dissolved phosphorus dynamics. The model's complexity was compared to one popular nutrient model, INCA‐P, and the performance of the two models was compared in a small rural catchment in northeast Scotland. For three land use classes, less than six SimplyP parameters must be determined through calibration, the rest may be based on measurements, while INCA‐P has around 40 unmeasurable parameters. Despite substantially simpler process‐representation, SimplyP performed comparably to INCA‐P in both calibration and validation and produced similar long‐term projections in response to changes in land management. Results support the hypothesis that INCA‐P is overly complex for the study catchment. We hope our findings will help prompt wider model comparison exercises, as well as debate among the water quality modeling community as to whether today's models are fit for purpose. Simpler models such as SimplyP have the potential to be useful management and research tools, building blocks for future model development (prototype code is freely available), or benchmarks against which more complex models could be evaluated.

Simulation and Validation of Cisco Lethal Conditions in Minnesota Lakes under Past and Future Climate Scenarios Using Constant Survival Limits

Fish habitat in lakes is strongly constrained by water temperature (T) and available dissolved oxygen (DO) that are changed under climate warming. A one dimensional, dynamic water quality model MINLAKE2012 was used for T and DO simulation over 48 years. A fish habitat model FishHabitat2013 using simulated T and DO profiles as input was developed to determine lethal conditions of cisco Corgenous artedi in Minnesota lakes. Twenty-three lakes that had observations of cisco mortality or survival in the unusually warm summer of 2006 were used for model validation. The cisco habitat model used a lethal temperature of 22.1 °C and DO survival limit of 3 mg/L determined through model validation and sensitivity analysis. Cisco lethal conditions in 12 shallow, 16 medium-depth, and 30 deep virtual lakes were then simulated. Isopleths of total number of years with cisco kill and average cisco kill days for the years with kills under past (1961–2008) and future climate were generated to understand/extrapolate climate impacts on cisco in 620 Minnesota lakes. Shallow and medium-depth lakes are projected to not be good candidates for cisco refuge lakes, but deep lakes are possible cisco refuge lakes based on lethal condition projection under future warmer climate.

동적모델을 이용한 수질오염총량제 목표수질 설정 및 할당부하량 산정방안 연구

In this study, the applicability of dynamic water quality model to TMDL system was examined, methods for setting of water quality goal and estimation of allocation loads were suggested and results of applying these methods were analyzed. HSPF model was applied for Miho stream basin as a dynamic water quality model. The model was calibrated using measurement data obtained in 2009~2010 and showed satisfactory performance in predicting daily variations of flow rate and BOD concentration. Methods for TMDL application were categorized into 3 cases; water quality management (1) considering low flow condition(Case I), (2) considering entire period of the year (Case II) and (3) considering the worst water quality condition (Case III). BOD water quality goals at the end of Miho stream watershed increased in the order of Case IICase I>Case III. If further researches on base precipitation and method for model input of nonpoint source pollutant were carried out, water quality could be managed more reasonably and scientifically by applying dynamic water quality model to TMDL. The result of this study is expected to be used as primary data for TMDL using dynamic water quality model.

Hydrodynamic and Water Quality Modeling of Lake Eğirdir

AbstractThe main objective of this study was to determine the impact of current point and nonpoint pollution loads on the water quality of Lake Eğirdir. For this purpose, hydrodynamics and water quality status of Lake Eğirdir were investigated by using the Delft3D model. The monthly monitoring of pH, dissolved oxygen (DO), chlorophyll‐a (Chl‐a), and forms of nitrogen and phosphorus was carried out, as was the seasonal monitoring of total organic carbon. In all, seven different sampling points were chosen from the lake and influent streams in order to monitor the lake during the period from December 2010 to November 2011, with the aim of calibrating the model. The performance of the dynamic water quality model was evaluated using the relative root mean square error (RRMSE) values for both the calibration and the validation periods. The results of the model showed that the DO had the lowest, and Chl‐a had highest associated RRMSE value. The simulation results showed that Segments 1 and 7 of the system had relatively high concentrations of almost all the pollutants. It was also found that increasing the nonpoint nutrient loads from agricultural sources has a greater effect than increasing the nonpoint nutrient loads from the inhabited areas around the lake.

Modelling impacts of seasonal wastewater treatment plant effluent permits and biosolid substitution for phosphorus management in catchments and river systems

The issues of diffuse and point source phosphorus (P) pollution in river systems are presented using a catchment model to assess nutrient behaviour, seasonal effluent standards and biosolid substitution. A process-based, dynamic water quality model (INCA-P) has been applied to four UK catchments, namely, the Rivers Tywi, Wensum, Lunan and Hampshire Avon, to simulate water fluxes, sediments, total phosphorus and soluble reactive phosphorus (SRP) concentrations. The model has been used to assess impacts of both agricultural runoff and point P sources from wastewater treatment plants (WWTPs) on water quality. With increasing costs for P fertilizer and P reduction at WWTPs, a strategy of recycling P from WWTPs as biosolids to substitute for fertilizers in vulnerable catchments has been investigated. Significant reductions in P concentrations are achieved if this substitution were implemented on a large scale. Reductions in SRP of between 6% and 41% can be achieved using this strategy. The effects of implementing new WWTP standards are shown to reduce SRP by 30%. Seasonal consent standards applied in only summer months could reduce SRP by 53% and achieve a substantial reduction in treatment costs year round.

Distributed and dynamic modelling of hydrology, phosphorus and ecology in the Hampshire Avon and Blashford Lakes: Evaluating alternative strategies to meet WFD standards

The issues of diffuse and point source phosphorus (P) pollution in the Hampshire Avon and Blashford Lakes are explored using a catchment model of the river system. A multibranch, process based, dynamic water quality model (INCA-P) has been applied to the whole river system to simulate water fluxes, total phosphorus (TP) and soluble reactive phosphorus (SRP) concentrations and ecology. The model has been used to assess impacts of both agricultural runoff and point sources from waste water treatment plants (WWTPs) on water quality. The results show that agriculture contributes approximately 40% of the phosphorus load and point sources the other 60% of the load in this catchment. A set of scenarios have been investigated to assess the impacts of alternative phosphorus reduction strategies and it is shown that a combined strategy of agricultural phosphorus reduction through either fertiliser reductions or better phosphorus management together with improved treatment at WWTPs would reduce the SRP concentrations in the river to acceptable levels to meet the EU Water Framework Directive (WFD) requirements. A seasonal strategy for WWTP phosphorus reductions would achieve significant benefits at reduced cost.

Calibration and validation of a dynamic model for water quality in combined sewer retention tanks

As the integrated management of urban wastewater systems becomes more and more popular, the development of wastewater management subsystem models appears essential to improve the understanding of the pollutant dynamics and their interactions. In such a context, a review of the literature reveals a lack of efficient models describing the dynamics of the water quality stored in off-line retention tanks. A model has thus been proposed based on the fractionation of suspended solids into three classes according to the particle settling velocity distribution measured in the field using the ViCAs settling test. In this paper, a calibration methodology is developed and full-scale field data sets from three different events are used for 1) calibrating this new dynamic retention tank model (two data sets); and 2) validating that model on the last data set. The results show a good agreement between observed and simulated data both for the total suspended solids and the total chemical oxygen demand.

A new dynamic water quality model for stormwater basins as a tool for urban runoff management: Concept and validation

In the context of real-time control of a stormwater basin's outlet gate to improve the river's water quality, while guaranteeing population safety, it is necessary to define and test scenarios over various environmental conditions and perform long term simulations. This paper presents a new dynamic model for stormwater basins, which can reproduce the evolution of the water quality in the basin. The developed model describes the behaviour of pollution associated with particles, accounting for the distribution of particle settling velocities. After detailing the model, simulation results of an experiment representing settling under quiescent hydraulic conditions, are presented to validate the developed model's concepts. The dynamic behaviour of a pollution associated with three particle settling velocity classes is presented before concluding on the perspectives that can be offered by such a model.

한강수계에서의 다차원 시변화 유기물 및 영양상태 모델 연구

Multidimensional dynamic water quality model of organic matter and trophic state was applied to the Han River system. The model was calibrated using field measurement data obtained during the year of 2007. The model results showed reasonable performance in predicting temporal variations of TN, TP, Chl-a and BOD concentrations. The applied integrated modeling system can be effectively used to simulate water quality as well as hydrodynamic and water temperature for river-lake continuous system in the Han River. Utilizing the calibrated model, we analyzed the spatial and temporal distributions of TN, TP, Chl-a and BOD concentrations in the Han River system. The temporal variations of water quality at each river reach and lake were effectively simulated with the developed model and spatial distribution of water qualities in the Han River system could be compared. The multidimensional dynamic modeling system can simulate the water qualities of entire waterbody where Lake Paldang and the incoming flows are included using single modeling system. So it can be effectively used for integrated water quality management of the Han River system.

부정류 흐름에서 상수관망 수질해석을 위한 동역학적 모형의 개발

A dynamic water quality model is presented in order to simulate water quality under slowly varying flow conditions over time. To improve numerical accuracy, the proposed model uses a lumped system approach instead of extended period simulation, unlike the other available models. This approach can achieve computational efficiency by assuming liquid and pipe walls to be rigid, unlike the method of characteristics, which has been successfully implemented in rapidly varying flows. The discrete volume method is applied to resolve the advection and reaction terms of the transport equation for water quality constituents in pipes. Numerical applications are implemented to the pipe network examples under steady and unsteady conditions as well as hydraulic and water quality simulations. The numerical results are compared with EPANET2, which is a widely used simulation model for a water distribution system. The model results are in good agreement with EPANET2 for steady-state simulation. However, the hydraulic simulation results under unsteady flows differ from those of EPANET2, which causes a deviation in water quality prediction. The proposed model is expected to be a component of an integrated operation model for a water distribution system if it is combined with a computational model for rapidly varying flows to estimate leakage, pipe roughness, and intensive water quality.

Simulations of water quality and oxythermal cisco habitat in Minnesota lakes under past and future climate scenarios

A deterministic, process-oriented, dynamic and one-dimensional year-round lake water quality model, MINLAKE2010, was developed for water temperature (T) and dissolved oxygen (DO) simulations to study impacts of climate warming on lake water quality and cisco fish habitat. The DO model is able to simulate metalimnetic oxygen maxima in vertical DO profiles of oligotrophic lakes. The model was calibrated with profile data from the 28 study lakes in Minnesota; two-thirds of them are deep mesotrophic/oligotrophic lakes that support cisco, a coldwater fish species. The average standard error of estimate against measured data was 1.47 °C for T and 1.50 mg/L for DO. Oxythermal habitat parameter TDO3 (T at DO = 3 mg/L) was determined from simulated daily T and DO profiles under past and future climate scenarios in the 28 study lakes. Average annual maximum TDO3 (TDO3AM) for the 28 study lakes is projected to increase on the average of 3.2 °C under the MIROC 3.2 future scenario, while the occurrence day of TDO3AM is not much different under past and future climate scenarios. Both physical processes (mixing characteristics related to lake geometry ratio) and trophic status control temperature and DO characteristics and then affect cisco habitat in a lake.

Dynamic risk assessment model for water quality on projection pursuit cluster

With the aim of reducing the losses from water pollution, a dynamic risk assessment model for water quality is studied in this paper. This model is built on the projection pursuit cluster principle and risk indexes in the complex system, proceeding from the whole structure and its component parts. In this paper, the fuzzy analytic hierarchy process is used to screen out index system and determine index weight, while the further value of an index is simulated by hydrological model. The proposed model adopts the comprehensive dynamic evaluation method to analyze the time dimension data, and evaluates the development tendency by combining qualitative analysis with quantitative analysis. The projection pursuit theory is also employed for clustering the spatial dimension data, the optimal projection vector for calculating risk cluster type to compartmentalize risk, and then local conditions for proposing the regulation scheme. The applicational results show that the model has the strong logic superiority and regional adaptability with strict theoretical system, flexible methods, correct and reasonable results and simple implementation to provide a new way for research on risk assessment models of water quality.

Water and nutrient predictions in ungauged basins: set-up and evaluation of a model at the national scale

A dynamic water quality model, HYPE, was applied to a large, data-sparse region to study whether reliable information on water quantity and water quality could be obtained for both gauged and ungauged waterbodies. The model (called S-HYPE) was set up for all of Sweden (∼450 000 km2), divided into sub-basins with an average area of 28 km2. Readily available national databases were used for physiographic data, emissions and agricultural practices, fixed values for representative years were used. Daily precipitation and temperature were used as the dynamic forcing of the model. Model evaluation was based on data from several hundred monitoring sites, of which approximately 90% had not been used in calibration on a daily scale. Results were evaluated using the Nash-Sutcliffe efficiency (NSE), correlation and relative errors: 92% of the spatial variation was explained for specific water discharge, and 88% and 59% for total nitrogen and total phosphorus concentrations, respectively. Day-to-day variations were modelled with satisfactory results for water discharge and the seasonal variation of nitrogen concentrations was also generally well captured. In 20 large, unregulated rivers the median NSE for water discharge was 0.84, and the corresponding number for 76 partly-regulated river basins was 0.52. In small basins, the NSE was typically above 0.6. These major achievements relative to previous similar experiments were ascribed to the step-wise calibration process using representative gauged basins and the use of a modelling concept, whereby coefficients are linked to physiographic variables rather than to specific sites. Editor D. Koutsoyiannis Citation Strömqvist, J., Arheimer, B., Dahné, J., Donnelly, C. and Lindström, G., 2012. Water and nutrient predictions in ungauged basins: set-up and evaluation of a model at the national scale. Hydrological Sciences Journal, 57 (2), 229–247.

Key uncertainty sources analysis of water quality model using the first order error method

In this study, key uncertainty sources analysis was undertaken for a dynamic water model using a First order error analysis method. First, a dynamic water quality model for the Three Gorges Reservoir Regions was established using data after impoundment by the environmental fluid dynamics code model package. Model calibration and verification were then conducted using measured data collected during 2004 and 2006. Four statistical indices were employed to assess the modeling efficiency. The results indicated that the model simulated the variables well, with most relative error being less than 25 %. Next, input and parameter uncertainty analysis were conducted for ammonia nitrogen, nitrate nitrogen, total nitrogen, and dissolved oxygen at 3 grid cells located in the upper, middle and downstream portions of the research area. For the nitrogen related variables, input from Zhutuo Station, the Jialingjiang River, and the Wujiang River were the main sources of uncertainty. Point and nonpoint sources also accounted for a large ratio of uncertainty. Moreover, nitrification contributed some uncertainty to the estimated ammonia nitrogen and nitrate nitrogen. However, reaeration was found to be a key source of uncertainty for dissolved oxygen, especially at the middle and downstream reaches. The analysis conducted in this study gives a quantitative assessment for uncertainty sources of each variable, and provides guidance for further pollutant loading reduction in the Three Gorge Reservoir Region.

동적수질해석모형의 개발과 낙동강에의 적용

본 연구의 목적은 저유량에서 발산하는 문제를 해결하여 다양한 흐름과 불규칙한 하도단면을 반영하는 안정적이고 정교한 동적수질해석모형을 개발하는데 있다. 이에 본 연구에서는 기존 모형들의 저유량에서 발산하는 문제를 해결하고자 확산파 운동방정식 기법을 이용하여 수리해석모형인 DyHYD를 개발하였으며, 수질해석모형은 자생 BOD와 수온, DO, TN, TP 등 12가지 수질농도를 계산할 수 있는 DyQUAL을 개발하였다. 개발된 모형의 적용성을 검토하기 위하여 가상하도 및 실제 낙동강유역에서 모의를 수행한 후 실측치와 비교 검토함으로써 모형의 적용성과 신뢰성을 검토하였다. 모형의 수행결과를 관측치와의 비교를 통해 Nash-Sutcliffe 계수를 산정하였으며, 보정과정에서는 유량과 BOD, TN, TP의 Nash-Sutcliffe 계수는 0.391에서 0.591의 범위를 나타내며, 검증과정에서는 0.704에서 0.902의 범위를 나타내었다. The objective of this study is to develop an accurate and stable dynamic water quality model which is capable of reflecting various flows and irregular cross sections and handling numerical oscillations under the low flow conditions. In order to solve the oscillation problem under the low flow conditions, diffusive wave method was applied to the low flow condition in developing a hydraulic model, DyHYD. DyQUAL is also developed as a water quality model to calculate up to 12 water quality variables including autochthonous BOD, water temperature, DO, TN and TP. The developed model is applied to both hypothetical river channels and actual Nakdong river watershed. Additionally, the applicability and reliability of the models are verified by comparing simulation results with observed values. Nash-Sutcliffe coefficients are estimated by comparison between simulation results and observed values. In the calibration and verification process, the coefficients varies from 0.391 to 0.591 and 0.704 to 0.902 for discharge, BOD, TN and TP, respectively.

Model of zebra mussel growth and water quality impacts in the Seneca River, New York

Glaser, D., J.R. Rhea, D.R. Opdyke, K.T. Russell, C.K. Ziegler, W. Ku, L. Zheng and J.J. Mastriano. 2009. Model of zebra mussel growth and water quality impacts in the Seneca River, New York. Lake Reserv. Manage. 25:49–72. A dynamic water quality model was developed to support management decision-making for the Seneca River, New York. The model incorporated two-dimensional hydrodynamics to simulate stratification observed within the system, a carbon-based zebra mussel growth model to account for the impact of this invasive species on water quality within the system, and a mechanistic representation of sediment diagenesis to account for zebra mussel-induced changes in carbon cycling. The Seneca River is on New York State's 303(d) list of impaired water bodies for nonattainment of dissolved oxygen criteria and is being considered as the potential receiving water for diverted effluent from an 85 million gallon per day (MGD) wastewater treatment plant (WWTP) serving the City of Syracuse, New York. The model was developed to examine the feasibility of such a diversion. The model was parameterized using site-specific field and laboratory studies and accurately simulated six years of routine, generally biweekly, river monitoring data for dissolved oxygen, chlorophyll-a, nitrogen, and phosphorus, collected over a range of flow conditions. The diagnostic application of the calibrated model provided valuable insights into the complex feedback mechanisms that exist within the system, particularly the role that zebra mussel filtration, respiration, and elimination have on phytoplankton production, sediment oxygen demand, and nutrient cycling within the system.