Uncertainty Analysis in Water Quality Modelling

1996 ◽  
Vol 27 (3) ◽  
pp. 203-214 ◽  
Author(s):  
Jan A. Høybye
Keyword(s):  
Water Quality ◽  
Mass Balance ◽  
Error Propagation ◽  
Numerical Models ◽  
Water Levels ◽  
Nutrient Concentrations ◽  
Monitoring Systems ◽  
Efficient Design ◽  
First Order ◽  
First Order Theory

An important part of regional planning of water resources and quality is efficient design of monitoring systems and proper use of hydrologic models (Beven 1993). In the design of monitoring systems as well as validation of numerical models, based on, for example, the equation of continuity such as hydrologic routing models and mass balance nutrient models, it is essential to estimate the uncertainties of the model-predictions. This paper presents an implementation of a first-order analysis for estimating the error-propagation when introducing mass balance models as to predict nutrient-concentrations. The uncertainty assessment, developed from a first order theory, is implemented in the analysis and modelling of Hjarbaek fjord in Denmark. The project includes hydrological modelling of input of water and nutrients to the fjord from tributaries, and a hydrodynamic estimation of water levels and velocities in the fjord. A two-system water quality box-model is used for estimation of concentrations in water and sediment phases. The system uncertainties are analysed, starting with input data uncertainties and the error propagation to the final concentration estimates, in order to optimise the future monitoring programme, and to control the model results.

Gold coast seaway smartrelease decision support system: optimising recycled water release in a sub tropical estuarine environment

2009 ◽  
Vol 60 (8) ◽  
pp. 2077-2084 ◽  
Author(s):  
G. Stuart ◽  
A. Hollingsworth ◽  
F. Thomsen ◽  
S. Szylkarski ◽  
S. Khan ◽  
...  
Keyword(s):  
Water Quality ◽  
Decision Support ◽  
Decision Support System ◽  
Support System ◽  
Numerical Models ◽  
Water Levels ◽  
Gold Coast ◽  
Recycled Water ◽  
Water Release ◽  
The Impact

Gold Coast Water is responsible for the management of the water, recycled water and wastewater assets of the City of the Gold Coast on Australia's east coast. Excess treated recycled water is released at the Gold Coast Seaway, a man-made channel connecting the Broadwater Estuary with the Pacific Ocean, on an outgoing tide in order for the recycled water to be dispersed before the tide changes and re-enters the Broadwater estuary. Rapid population growth has placed increasing demands on the city's recycled water release system and an investigation of the capacity of the Broadwater to assimilate a greater volume of recycled water over a longer release period was undertaken in 2007. As an outcome, Gold Coast Water was granted an extension of the existing release licence from 10.5 hours per day to 13.3 hours per day from the Coombabah wastewater treatment plant (WWTP). The Seaway SmartRelease Project has been designed to optimise the release of the recycled water from the Coombabah WWTP in order to minimise the impact to the receiving estuarine water quality and maximise the cost efficiency of pumping. In order achieve this; an optimisation study that involves intensive hydrodynamic and water quality monitoring, numerical modelling and a web-based decision support system is underway. An intensive monitoring campaign provided information on water levels, currents, winds, waves, nutrients and bacterial levels within the Broadwater. This data was then used to calibrate and verify numerical models using the MIKE by DHI suite of software. The Decision Support System will then collect continually measured data such as water levels, interact with the WWTP SCADA system, run the numerical models and provide the optimal time window to release the required amount of recycled water from the WWTP within the licence specifications.

scholarly journals Effects of extreme water levels on water quality in a large shallow eutrophic lake (Changhu Lake, China)

2021 ◽  
Author(s):  
Haiyan Wang ◽  
Jun Yang ◽  
Tao Li ◽  
Jianqiang Zhu ◽  
Zhangyong Liu
Keyword(s):  
Water Quality ◽  
Water Level ◽  
Eutrophic Lake ◽  
High Water ◽  
Water Levels ◽  
Central China ◽  
Nutrient Concentrations ◽  
High Water Level ◽  
Extreme Water Levels ◽  
Shallow Eutrophic Lake

Abstract Changhu Lake, a large shallow eutrophic lake in central China, experienced an extreme low water level event from November 2015 to January 2016 followed by an extreme high water level event in July 2016. In this study, we examined the effects of two extreme water levels on the nutrient status of Changhu Lake over five years. The nutrient concentrations in Changhu Lake showed significant interannual variations and the water quality of sites in the western part of Changhu Lake was better compared to sites at the outlet of the lake. In late 2015, the effect of low water levels led to a significant increase in nutrient concentrations. After July 2016, however, the high water level occurred leading to a marked decrease in nutrient concentrations. These changes in nutrient parameters were strongly related to the water level fluctuations. The dilution effect was the key process that determined the variations of nutrient parameters in Changhu Lake. As extreme water levels are likely to become more frequent during the twenty-first century, this work may provide some insights into the conservation and management of lake ecosystems in the face of climate change and human activity.

scholarly journals A Review of 50 Years of Study of Hydrology, Wetland Dynamics, Aquatic Metabolism, Water Quality and Trophic Status, and Nutrient Biogeochemistry in the Barataria Basin, Mississippi Delta—System Functioning, Human Impacts and Restoration Approaches

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 642 ◽  
Author(s):  
John W. Day ◽  
William H. Conner ◽  
Ronald D. DeLaune ◽  
Charles S. Hopkinson ◽  
Rachael G. Hunter ◽  
...  
Keyword(s):  
Water Quality ◽  
Mississippi Delta ◽  
Human Impacts ◽  
Forested Wetlands ◽  
Wetland Loss ◽  
Water Levels ◽  
Nutrient Concentrations ◽  
Island Restoration ◽  
Barataria Basin ◽  
System Functioning

Here we review an extensive series of studies of Barataria Basin, an economically and ecologically important coastal basin of the Mississippi Delta. Human activity has greatly altered the hydrology of the basin by decreasing riverine inflows from leveeing of the river and its distributaries, increasing runoff with high nutrient concentrations from agricultural fields, and channelization of wetlands of the basin interior that has altered flow paths to often bypass wetlands. This has resulted in degraded water quality in the upper basin and wetland loss in the lower basin. Trophic state analysis found the upper basin to be eutrophic and the lower basin to be mesotrophic. Gross aquatic primary production (GAPP) was highest in the upper basin, lowest in the mid basin, and intermediate in the lower basin. Forested wetlands in the upper basin have degraded over the past several decades due to increased periods of flooding, while there has been massive loss of emergent wetlands in the lower basin due to increasing water levels and pervasive alteration of hydrology. Restoration will entail reconnection of waterways with surrounding wetlands in the upper basin, and implementation of river sediment diversions, marsh creation using dredged sediments and barrier island restoration. Findings from this review are discussed in terms of the functioning of deltas globally.

Nappes d'huile: prediction de leurs deplacements comme agent efficace d'un plan de mesure d'urgence

1979 ◽  
Vol 14 (1) ◽  
pp. 89-109
Author(s):  
B. Coupal ◽  
M. de Broissia
Keyword(s):  
Monte Carlo ◽  
Markov Chain ◽  
Finite Elements ◽  
Mass Balance ◽  
Stochastic Method ◽  
Stochastic Methods ◽  
Deterministic Approach ◽  
First Order ◽  
The Third ◽  
Comme Agent

Abstract The movement of oil slicks on open waters has been predicted, using both deterministic and stochastic methods. The first method, named slick rose, consists in locating an area specifying the position of the slick during the first hours after the spill. The second method combines a deterministic approach for the simulation of current parameters to a stochastic method simulating the wind parameters. A Markov chain of the first order followed by a Monte Carlo approach enables the simulation of both phenomena. The third method presented in this paper describes a mass balance on the spilt oil, solved by the method of finite elements. The three methods are complementary to each other and constitute an important point for a contingency plan.

Nutrient Input and Trophic Status of the “Neue Donau”, a High-Water Control System along the River Danube in Vienna, Austria

1990 ◽  
Vol 22 (5) ◽  
pp. 137-144 ◽  
Author(s):  
M. T. Dokulil ◽  
G. A. Janauer
Keyword(s):  
Water Quality ◽  
Control System ◽  
Trophic Status ◽  
High Water ◽  
Nutrient Concentrations ◽  
Nutrient Input ◽  
Water Control ◽  
Trophic Conditions ◽  
River Danube ◽  
High Nutrient

The system “Neue Donau” functions as a control system for high waters of the river Danube and is an important recreational area for many people. Water quality and trophic status of the water body is thereforeof prime importance. The high nutrient concentrations of the river Danube (P-tot 238±41µg/l, N-tot 2.53±0.78 mg/l) reach the system via groundwater seepage. Present conditions in the basin of Neue Donau are,as a result of this nutrient in-flux,eutrophic to hypertrophic. Average values during the summer period have declined from 366 µg/l total phosphorus to 78 µg/l, and from 86 µg/l chlorophyll-a tol7µg/l between the years 1985 and 1988. However, a dam which is planned in the river at Vienna will permanently raise the water level of the river thus increasing the the groundwater flow in the direction to the Neue Donau and therefore the nutrient input which will enhance trophic conditions in the impoundment. Since macrophytes play an important role in one part of the system macrophyte management together with measures along the river are some of the suggested strategies to keep the system Neue Donau at acceptable trophic conditions and good water quality.

scholarly journals Assessment of Automatically Monitored Water Levels and Water Quality Indicators in Rivers with Different Hydromorphological Conditions and Pollution Levels in Greece

Hydrology ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 86
Author(s):  
Angeliki Mentzafou ◽  
George Varlas ◽  
Anastasios Papadopoulos ◽  
Georgios Poulis ◽  
Elias Dimitriou
Keyword(s):  
Water Quality ◽  
Time Series ◽  
Quality Indicators ◽  
High Frequency ◽  
Automatic Monitoring ◽  
Water Levels ◽  
High Temporal Resolution ◽  
Water Quality Indicators ◽  
Pollution Levels ◽  
Riverine Ecosystems

Water resources, especially riverine ecosystems, are globally under qualitative and quantitative degradation due to human-imposed pressures. High-temporal-resolution data obtained from automatic stations can provide insights into the processes that link catchment hydrology and streamwater chemistry. The scope of this paper was to investigate the statistical behavior of high-frequency measurements at sites with known hydromorphological and pollution pressures. For this purpose, hourly time series of water levels and key water quality indicators (temperature, electric conductivity, and dissolved oxygen concentrations) collected from four automatic monitoring stations under different hydromorphological conditions and pollution pressures were statistically elaborated. Based on the results, the hydromorphological conditions and pollution pressures of each station were confirmed to be reflected in the results of the statistical analysis performed. It was proven that the comparative use of the statistics and patterns of the water level and quality high-frequency time series could be used in the interpretation of the current site status as well as allowing the detection of possible changes. This approach can be used as a tool for the definition of thresholds, and will contribute to the design of management and restoration measures for the most impacted areas.

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