Dynamic Simulation Of Water Quality Research Articles

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.

IberWQ: new simulation tool for 2D water quality modelling in rivers and shallow estuaries

This paper presents a new freeware simulation tool (IberWQ) for 2D water quality modelling in rivers and non-stratified estuaries. The model computes the spatial and temporal evolution of several species and variables which are relevant for the evaluation of the environmental status of rivers and estuaries, including: Escherichia coli, dissolved oxygen, carbonaceous biochemical oxygen demand, organic nitrogen, ammoniacal nitrogen, nitrate–nitrite nitrogen, water temperature and salinity. A depth-averaged transport equation is solved for each variable with a mass conservative unstructured finite volume solver. IberWQ is fully coupled to the hydrodynamic module of the software Iber, a freeware simulation tool for solving the 2D shallow water equations. Both models are integrated in the same windows graphical environment, including several tools which allow the user to generate unstructured meshes adapted to the site topography, define spatially variable input parameters and visualize model outputs. We present four application examples to illustrate the possibilities of the software for the dynamic simulation of water quality in rivers and estuaries.

CALHIDRA 3.0 – New software application for river water quality prediction based on RWQM1

This paper presents CalHidra 3.0, a new software package developed for dynamic simulation of water quality in rivers. CalHidra 3.0 combines a 1-D hydrodynamic model based on Saint Venant equations, a transport sub-model that incorporates the advection–dispersion terms, and a simplified version of the River Water Quality Model 1 (RWQM1) for the biochemical transformations. This advanced biochemical sub-model allows the dynamic simulation of the bacterial populations in rivers, making possible the simulation of the river acclimatisation to changes of pollutant load or environmental conditions. The software also includes new tools for a Monte Carlo based Bayesian calibration of the unknown model parameters. CalHidra 3.0 is implemented based on the Component Object Model (COM) programming paradigm and uses the Windows graphical environment. Three case studies illustrate the possibilities of the CalHidra 3.0 software.

Effect of a seasonal diffuse pollution migration on natural organic matter behavior in a stratified dam reservoir

This article aims to describe the influence of diffuse pollution on the temporal and spatial characteristics of natural organic matter (NOM) in a stratified dam reservoir, the Daecheong Dam, on the basis of intensive observation results and the dynamic water quality simulation using CE-QUAL-W2. Turbidity is regarded as a comprehensive representation of allochothonous organic matter from diffuse sources in storm season because the turbidity concentration showed reasonable significance in a statistical correlation with the UV absorbance at 254 nm and total phosphorus. CE-QUAL-W2 simulation results showed good consistency with the observed data in terms of dissolved organic matter (DOM) including refractory dissolved organic carbon (RDOC) and labile DOC and also well explained the internal movement of constituents and stratification phenomenon in the reservoir. Instead turbidity and NOM were related well in the upper region of the reservoir according to flow distance, gradually as changing to dissolved form of organic matter, RDOM affected organic matter concentration of reservoir water quality compared to turbidity. To control the increase of soluble organic matters in the dam reservoir, appropriate dam water discharge gate operation provided effective measurement. Because of the gate operation let avoid the accumulation of organic matter within a dam reservoir by shorten of turbid regime retention time.

총량규제에 따른 주암호의 장래 수질 예측

When the Juam multipurpose dam which is connected with existing large water supply facilities is finished, water environment is changed from stream to lake. The changed quality of water should be examined. In this study, the result of water quality forecasting is analysed and an effective management plan of water quality is presented. Tn this study, the WASPS model that is a dynamic water quality simulation model was selected to forecast the water quality. This model forecasts movement of change of pollutants. For an application of the model, the subject areas were divided into seventeen sub-areas by considering change temperature depending measuring points and on depth of water. Meteorological data collected by the meteorological observatory and data about quality measured by the Korea Water Resources Development Corporation were used for an operation of the model. As a result of quality examination through quality data and estimated pollutant loading, the water quality environment criterion was grade II and the nutritive condition was measured as meso-graphic grade. In this study, an effective management was planned to improve water quality by reducing pollution load. According to the result of examination, when more than 30% of BOD was reduced it was recorded that the environment standard of water quality was improved to the second grade.

SWAT 및 KoRiv1 모형을 활용한 하류하천 탁도관리 시스템구축

High turbid water in the River has been one of the major concerns to the downstream residence. Especially in the Nakdong River basin severe turbid water problem occurred in year 2002 and 2003 due to the typhoon Rusa and Maemi consecutively. The main objective of this study is to develop turbid water management system in reservoir downstream of the Nakdong River combining physically based semi-distributed hydrologic simulation model SWAT with 1-dimensional dynamic water quality simulation model. SWAT model covers the area from the upstream of the Imha and Andong reservoir to the Gumi gage station for the purpose of estimating flow rates and suspended sediment of the tributaries. From year 1999 to 2007 runoff simulation for 8 years <TEX>$R_{eff}$</TEX> and <TEX>$R^2$</TEX> ranges <TEX>$0.46{\sim}0.9$</TEX>, <TEX>$0.54{\sim}0.99$</TEX> respectively. Through the linkage of models, outputs of SWAT model such as suspended sediment and flow rates of the tributaries can be incorporated into the 1-dimensional dynamic water quality simulation model, KoRiv1 to support joint reservoir operation considering the turbidity released from Imha and Andong reservoir. The applicability of model simulation has been tested for year 2006 and compared with measured data.

DETERMINING CRITICAL WATER QUALITY CONDITIONS FOR INORGANIC NITROGEN IN DRY, SEMI‐URBANIZED WATERSHEDS1

ABSTRACT: Traditional approaches to establishing critical water quality conditions, based on statistical analysis of low flow conditions and expressed as a recurrence interval for low flow conditions (e.g., 7Q10), may be inappropriate for drier watersheds. The use of 7Q10 as a standard design flow assumes year‐round flow, but in these watersheds, 7Q10 is zero or very small. In addition, the increasing use of multiple year dynamic water quality models at daily time steps can supercede the use of steady state approaches. Many of these watersheds are also under increasing urbanization pressure, which accentuates the flashiness of runoff and the episodic nature of critical water quality conditions. To illustrate, the conditions in the Santa Clara River, California, are considered. A statistical analysis indicates that higher inorganic nitrogen concentrations correlate strongly with low flow. However, peaks in concentrations can occur during the first storms, particularly where nonpoint source contribution is significant. Critical conditions can thus occur at different flow regimes depending on the relative magnitude of flow and pollutant contributions from various sources. The use of steady state models for these dry semi‐urbanized watersheds based on 7Q10 flows is thus unlikely to accurately simulate the potential for exceeding water quality objectives. Dynamic simulation of water quality is necessary, and as the recent intense storm event sampling data indicate, the models should be formulated to consider even smaller time steps. This places increasing demand on computational resources and datasets to accurately calibrate the models at this temporal resolution.

Chebyshev Model for Water-Quality Management

A Chebyshev criterion is used to develop robust direct regulation water-quality management models. The reserve capacity of the stream, in terms of the excess capacities above the water-quality goal at the most critical water-quality checkpoints, is used as a measure of robustness of the management solutions to uncertainties in the water-quality input information. The models maximize the minimum reserve capacity along the river. They are applied to the control of biochemical oxygen–demanding waste in an example river basin based on the Willamette River in Oregon. The addition of a robustness measure in the model formulation gives additional insight into the management system. Although the mathematical formulation of the application is simple, the results provide important information for decision makers, such as identifying polluters with high waste-treatment cost per unit dissolved oxygen improvement at the critical stream locations. Such information is often useful for screening alternative options and making sophisticated water-quality policy and management decisions, based on detailed dynamic water-quality simulation.

DYNAMIC (MATHEMATICAL) MODELING OF LAKE PROCESSES FOR MANAGEMENT DECISIONS

ABSTRACT Selecting a lake improvement method can be facilitated by computer simulation of the effects of various alternatives on lake water quality. Dynamic simulation of cause/effect relationships on the most important physical, chemical, and biological processes encountered in a lake allows extrapolation to future conditions on a rational basis. Not all lake processes are understood well enough to be properly modeled. However, features such as temperature stratification, turbidity, nutrient levels, and phytoplankton populations have been simulated successfully. A discussion of types of lake improvement techniques which can be simulated and those which cannot be simulated will be made. Examples of simulations evaluating improvement techniques will be given. Dynamic water quality simulation is an efficient and rational tool to compare quality and cost effectiveness of certain lake improvement techniques.