Calibration of QUAL2E Model for the Sava River (Slovenia)

The use of mathematical models is a good decision making tool in river basin management for selection of wastewater treatment technologies and for estimation of the impact of discharged wastewater on the quality of receiving streams. In rivers mostly polluted with degradable organic matter, the major effect of wastewater discharge results in a substantial decrease of dissolved oxygen. The model QUAL2E developed by the United States Environmental Protection Agency was applied to wastewater impact assessment in the Sava river (Slovenia). We present the procedures for the determination of input data for the QUAL2E model. The sediment oxygen demand rate constant was determined experimentally in situ using an specially designed device; the degradation rate constant was determined in a river laboratory model; hydrological characteristics were evaluated on the basis of empirical coefficients; while the reaeration rate constant was calculated on the basis of an energy dissipation model. The mathematical water quality model QUAL2E was calibrated on the basis of field and laboratory measurements and validated with an independent set of data for critical summer low flow conditions when the dissolved oxygen concentrations are low. A sensitivity analysis of the model was also performed. The validated model was then used to estimate the impact of municipal and industrial wastewater discharges on dissolved oxygen concentrations in the Sava river near Ljubljana. The model was used to simulate various conditions in the river and various degrees of treatment of discharged wastewaters. It is estimated according to the model predictions that at critical summer low flow conditions, wastewater should be treated to reach a BOD under 30 mg l−1 with the goal that Slovenian water quality standards are not violated, meaning a dissolved oxygen concentration above 5 mg l−1.

Download Full-text

Numerical investigation on the impact of wind-induced hydraulics on dissolved oxygen characteristics in a shallow stormwater pond

Water Quality Research Journal ◽

10.2166/wqrj.2019.002 ◽

2019 ◽

Vol 54 (4) ◽

pp. 309-325 ◽

Cited By ~ 3

Author(s):

Liyu Chen ◽

Patrick M. D'Aoust ◽

Colin D. Rennie ◽

Alexandre Poulain ◽

Frances Pick ◽

...

Keyword(s):

Water Quality ◽

Wind Speed ◽

Dissolved Oxygen ◽

Surface Wind ◽

Acoustic Doppler Current Profiler ◽

Low Flow ◽

Water Quality Control ◽

Current Profiler ◽

Wind Driven Currents ◽

The Impact

Abstract Stormwater ponds (SWPs) are widely utilized for flood and water quality control. Low-flow rates are common in SWPs, sometimes causing wind-driven currents to become the dominant hydrodynamic force during ice-free periods. Hence, it is essential to understand the influence of the wind-induced flow on stratification and dissolved oxygen (DO) concentrations in shallow SWPs to predict the performance and water quality of these systems. The objective of this study is to evaluate the influence of wind-driven circulation on the spatial distribution of DO in an SWP using a numerical model. A bottom-mounted acoustic Doppler current profiler (ADCP) was utilized to measure small wind-induced currents and to validate a hydrodynamic model, which suggested that a wind-dominated circulation was generated even with the moderate wind speed. Countercurrents opposite in the direction to surface wind-generated flow were also present. The DO model demonstrated that complete mixing can be produced by higher wind speed, leading to fully oxic conditions throughout the water column (7.00 mg/L DO or higher), wherein low DO water at depth was carried to the surface by upwelling circulation and was possibly replenished during the surface transportation. This sheds some light on the impact of wind-induced mixing on the water quality in shallow SWPs.

Download Full-text

A New Life for the St. Croix River

Water Quality Research Journal ◽

10.2166/wqrj.1988.044 ◽

1988 ◽

Vol 23 (4) ◽

pp. 568-577

Author(s):

Harold S. Bailey

Keyword(s):

Water Quality ◽

Dissolved Oxygen ◽

Discharge Rate ◽

Paper Mill ◽

Regulated River ◽

Secondary Treatment ◽

Pulp And Paper Mill ◽

Oxygen Regime ◽

Oxygen Concentrations

Abstract The water quality of the upper 110 kilometres of the St. Croix River is considered to be pristine. A major industrial discharge renders the lower 14 kilometres of the river a water quality limited segment. Prior to 1970 the Georgia-Pacific Pulp and Paper Mill at Woodland, Maine, discharged untreated effluent directly into the river causing dissolved oxygen concentrations to drop well below 5 mg/L, the objective chosen in the interest of restoring endemic fish populations. Since 1972, the Mill has installed primary and secondary treatment, regulated river discharge rate and effluent composition which has greatly improved the summer dissolved oxygen regime. By 1980, dissolved oxygen concentrations were generally above 5.0 mg/L and restocking the river with Atlantic Salmon (Salmo salar) was initiated.

Download Full-text

Considering the impact of intermittent discharges when modelling overflows

Water Science & Technology ◽

10.2166/wst.1998.0370 ◽

1998 ◽

Vol 38 (10) ◽

pp. 23-30

Author(s):

Sarah Jubb ◽

Philip Hulme ◽

Ian Guymer ◽

John Martin

Keyword(s):

Water Quality ◽

Dissolved Oxygen ◽

Preliminary Investigation ◽

Oxygen Demand ◽

Sediment Oxygen Demand ◽

Combined Sewer Overflows ◽

River Hydraulics ◽

Combined Sewer ◽

The Impact ◽

Curve Equation

This paper describes a preliminary investigation that identified factors important in the prediction of river water quality, especially regarding dissolved oxygen (DO) concentration. Intermittent discharges from combined sewer overflows (CSOs) within the sewerage, and overflows at water reclamation works (WRW) cause dynamic conditions with respect to both river hydraulics and water quality. The impact of such discharges has been investigated under both wet and dry weather flow conditions. Data collected from the River Maun, UK, has shown that an immediate, transient oxygen demand exists downstream of an outfall during storm conditions. The presence of a delayed oxygen demand has also been identified. With regard to modelling, initial investigations used a simplified channel and the Streeter-Phelps (1925) dissolved oxygen sag curve equation. Later, a model taking into account hydrodynamic, transport and dispersion processes was used. This suggested that processes other than water phase degradation of organic matter significantly affect the dissolved oxygen concentration downstream of the location of an intermittent discharge. It is proposed that the dynamic rate of reaeration and the sediment oxygen demand should be the focus of further investigation.

Download Full-text

Citizen Science Tools Reveal Changes in Estuarine Water Quality Following Demolition of Buildings

Remote Sensing ◽

10.3390/rs13091683 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1683

Author(s):

Nandini Menon ◽

Grinson George ◽

Rajamohananpillai Ranith ◽

Velakandy Sajin ◽

Shreya Murali ◽

...

Keyword(s):

Water Quality ◽

Dissolved Oxygen ◽

Citizen Science ◽

Secchi Depth ◽

Lake Water Quality ◽

Demolition Waste ◽

Water Colour ◽

Water Quality Variables ◽

The Impact

Turbidity and water colour are two easily measurable properties used to monitor pollution. Here, we highlight the utility of a low-cost device—3D printed, hand-held Mini Secchi disk (3DMSD) with Forel-Ule (FU) colour scale sticker on its outer casing—in combination with a mobile phone application (‘TurbAqua’) that was provided to laymen for assessing the water quality of a shallow lake region after demolition of four high-rise buildings on the shores of the lake. The demolition of the buildings in January 2020 on the banks of a tropical estuary—Vembanad Lake (a Ramsar site) in southern India—for violation of Indian Coastal Regulation Zone norms created public uproar, owing to the consequences of subsequent air and water pollution. Measurements of Secchi depth and water colour using the 3DMSD along with measurements of other important water quality variables such as temperature, salinity, pH, and dissolved oxygen (DO) using portable instruments were taken for a duration of five weeks after the demolition to assess the changes in water quality. Paired t-test analyses of variations in water quality variables between the second week of demolition and consecutive weeks up to the fifth week showed that there were significant increases in pH, dissolved oxygen, and Secchi depth over time, i.e., the impact of demolition waste on the Vembanad Lake water quality was found to be relatively short-lived, with water clarity, colour, and DO returning to levels typical of that period of year within 4–5 weeks. With increasing duration after demolition, there was a general decrease in the FU colour index to 17 at most stations, but it did not drop to 15 or below, i.e., towards green or blue colour indicating clearer waters, during the sampling period. There was no significant change in salinity from the second week to the fifth week after demolition, suggesting little influence of other factors (e.g., precipitation or changes in tidal currents) on the inferred impact of demolition waste. Comparison with pre-demolition conditions in the previous year (2019) showed that the relative changes in DO, Secchi depth, and pH were very high in 2020, clearly depicting the impact of demolition waste on the water quality of the lake. Match-ups of the turbidity of the water column immediately before and after the demolition using Sentinel 2 data were in good agreement with the in situ data collected. Our study highlights the power of citizen science tools in monitoring lakes and managing water resources and articulates how these activities provide support to Sustainable Development Goal (SDG) targets on Health (Goal 3), Water quality (Goal 6), and Life under the water (Goal 14).

Download Full-text

Surface-water-quality assessment of the lower Kansas River basin, Kansas and Nebraska; dissolved oxygen and Escherichia coli bacteria in streams during low flow, July 1988 through July 1989

10.3133/wri944077 ◽

1995 ◽

Keyword(s):

Escherichia Coli ◽

Water Quality ◽

Surface Water ◽

Dissolved Oxygen ◽

Quality Assessment ◽

Surface Water Quality ◽

Water Quality Assessment ◽

Low Flow ◽

Kansas River ◽

Escherichia Coli Bacteria

Download Full-text

Modeling Changes in the Water Quality of the Sava River Caused by Impounding Water at the Vrhovo Hydroelectric Power Plant

Water Science & Technology ◽

10.2166/wst.1990.0024 ◽

1990 ◽

Vol 22 (5) ◽

pp. 161-166

Author(s):

Uroš Krajnc ◽

Mitja Rismal

Keyword(s):

Water Quality ◽

Power Plant ◽

Hydroelectric Power Plant ◽

Hydroelectric Power ◽

Sava River ◽

The Sava River

Download Full-text

River flow abstraction due to hydraulic storage at freezeup

Canadian Journal of Civil Engineering ◽

10.1139/l08-128 ◽

2009 ◽

Vol 36 (3) ◽

pp. 519-523 ◽

Cited By ~ 9

Author(s):

Spyros Beltaos

Keyword(s):

Water Quality ◽

River Flow ◽

Ice Cover ◽

Low Flow ◽

Flow Data ◽

Flow Conditions ◽

Ice Concentration ◽

Cover Thickness ◽

Water Quality And Quantity

A hydrologic extreme that can be partly generated by ice effects is low winter flow, which is known for potential impacts on water quality and quantity of rivers receiving effluent discharges or industrial withdrawals. Flow abstraction caused by hydraulic storage during the upstream propagation of an ice cover is quantified using the equations of continuity for ice and water. The flow abstraction is shown to increase with increasing ice concentration, but to decrease with increasing ice cover thickness. Numerical values are consistent with winter abstractions indicated by flow data from Canadian hydrometric stations. The present results further suggest that low-flow conditions in winter should generally improve, or at least not deteriorate, under a warmer climate.

Download Full-text

Fish Rescue during Streamflow Intermittency May Not Be Effective for Conservation of Rio Grande Silvery Minnow

Water ◽

10.3390/w12123371 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3371

Author(s):

Thomas P. Archdeacon ◽

Tracy A. Diver ◽

Justin K. Reale

Keyword(s):

Water Quality ◽

Dissolved Oxygen ◽

Fish Assemblages ◽

Sublethal Effects ◽

Rio Grande ◽

Quality Data ◽

Water Quality Data ◽

Low Dissolved Oxygen ◽

Rio Grande Silvery Minnow ◽

Oxygen Concentrations

Streamflow intermittency can reshape fish assemblages and present challenges to recovery of imperiled species. During streamflow intermittency, fish can be subjected to a variety of stressors, including exposure to crowding, high water temperatures, and low dissolved oxygen, resulting in sublethal effects or mortality. Rescue of fishes is often used as a conservation tool to mitigate the negative impacts of streamflow intermittency. The effectiveness of such actions is rarely evaluated. Here, we use multi-year water quality data collected from isolated pools during rescue of Rio Grande silvery minnow Hybognathus amarus, an endangered minnow. We examined seasonal and diel water quality patterns to determine if fishes are exposed to sublethal and critical water temperatures or dissolved oxygen concentrations during streamflow intermittency. Further, we determined survival of rescued Rio Grande silvery minnow for 3–5 weeks post-rescue. We found that isolated pool temperatures were much warmer (>40 °C in some pools) compared to upstream perennial flows, and had larger diel fluctuations, >10 °C compared to ~5 °C, and many pools had critically low dissolved oxygen concentrations. Survival of fish rescued from isolated pools during warmer months was <10%. Reactive conservation actions such as fish rescue are often costly, and in the case of Rio Grande silvery minnow, likely ineffective. Effective conservation of fishes threatened by streamflow intermittency should focus on restoring natural flow regimes that restore the natural processes under which fishes evolved.

Download Full-text