Considering the impact of intermittent discharges when modelling overflows

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.

Impact of proposed Glengowan Dam flow augmentation on Thames River water quality

1984 ◽  
Vol 11 (3) ◽  
pp. 459-473
Author(s):  
T. P. Halappa Gowda ◽  
R. J. Dewey
Keyword(s):  
Water Quality ◽  
River Water ◽  
Deterministic Model ◽  
Oxygen Demand ◽  
River Water Quality ◽  
Sediment Oxygen Demand ◽  
Treated Wastewater ◽  
Macrophyte Community ◽  
Thames River ◽  
The Impact

The Thames River water management study report, prepared in 1975 by the Ontario Ministries of Natural Resources and Environment, recommended the construction of the Glengowan Dam primarily for flow augmentation to improve the river water quality (Recommendation No. 1). As part of the environmental impact assessment of the proposed dam, detailed water quality prediction studies were carried out using deterministic and stochastic models to evaluate the impact of the proposed flow augmentation and wastewater loading options. The river receives treated wastewater effluents from five water pollution control plants (WPCP) in the study area, all located within the City of London. The processes simulated by the models include advection, decay of carbonaceous and nitrogenous oxygen demand (CBOD and NOD), sediment oxygen demand, atmospheric reaeration, and respiration and photosynthetic activity of aquatic macrophyte community. The options modelled include (a) projected CBOD and NOD loading rates from the five WPCP's for the planning period 1981–2001; (b) low flows attainable with augmentation from existing Fanshawe reservoir and the proposed Glengowan Dam; and (c) zero loadings to the Thames River from WPCP's, attainable with effluent bypassing to Lake Erie. The results of the modelling studies are presented in this paper. Key words: water quality, dissolved oxygen, flow augmentation, environmental assessment, Glengowan Dam, Thames River Basin, deterministic model, stochastic model.

Caractérisation des eaux usées de débordements de réseau unitaire

1985 ◽  
Vol 12 (3) ◽  
pp. 527-537 ◽  
Author(s):  
Paul Lessard ◽  
Pierre Lavallée
Keyword(s):  
Water Quality ◽  
Rain Event ◽  
Combined Sewer Overflows ◽  
Drainage Basins ◽  
Combined Sewer ◽  
Different Types ◽  
Rain Events ◽  
The Impact ◽  
The City

In 1981, the City of Québec signed a protocol with the Québec Ministry of Environment permitting the study of the impact of combined sewer overflows (CSO) during rain periods on the St-Charles River. One of the main study objectives was to characterize CSO, both quantitatively and qualitatively. Five main drainage basins, representative of the study area, were selected and sampled during nine rain events. Certain appraisals were made to explain the importance of the water quality variations during rain events in combined sewers, dry weather period influence on runoff quality, and "first-flush" phenomenon. Two principal conclusions have been drawn from these data: (1) the major part of the pollutant load routed through a combined sewer network during a rain event is generated by surface runoff and dragging of sewage deposits and (2) the overall water quality of CSO doesn't seem to vary much from one basin to another, even if the percentages associated with different types of land use (residential, commercial, industrial, etc.) are different. Key words: urban runoff, combined sewer overflow, rainfall, quality, concentration, load.

Methods for studying dissolved oxygen levels in coastal and estuarine waters receiving combined sewer overflows

1995 ◽  
Vol 32 (2) ◽  
pp. 95-103
Author(s):  
José A. Revilla ◽  
Kalin N. Koev ◽  
Rafael Díaz ◽  
César Álvarez ◽  
Antonio Roldán
Keyword(s):  
Dissolved Oxygen ◽  
Coastal Waters ◽  
Computational Cost ◽  
Oxygen Deficit ◽  
Alternative Methods ◽  
Coastal Zones ◽  
Combined Sewer Overflows ◽  
Sewer Systems ◽  
Combined Sewer ◽  
High Computational Cost

One factor in determining the transport capacity of coastal interceptors in Combined Sewer Systems (CSS) is the reduction of Dissolved Oxygen (DO) in coastal waters originating from the overflows. The study of the evolution of DO in coastal zones is complex. The high computational cost of using mathematical models discriminates against the required probabilistic analysis being undertaken. Alternative methods, based on such mathematical modelling, employed in a limited number of cases, are therefore needed. In this paper two alternative methods are presented for the study of oxygen deficit resulting from overflows of CSS. In the first, statistical analyses focus on the causes of the deficit (the volume discharged). The second concentrates on the effects (the concentrations of oxygen in the sea). Both methods have been applied in a study of the coastal interceptor at Pasajes Estuary (Guipúzcoa, Spain) with similar results.

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

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).

Experimental manipulations of the biomass of introduced carp (Cyprinus carpio) in billabongs. II. Impacts on benthic properties and processes1

1997 ◽  
Vol 48 (5) ◽  
pp. 445 ◽  
Author(s):  
A. I. Robertson ◽  
M. R. Healey ◽  
A. J. King
Keyword(s):  
Algal Biomass ◽  
Solid Phase ◽  
Negative Impact ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Sediment Surface ◽  
Nutrient Concentrations ◽  
Nutrient Ratios ◽  
Biofilm Development ◽  
The Impact

Two billabongs on the floodplain of the Murrumbidgee River, Australia, were partitioned in half with impermeable plastic barriers and the biomass of carp was manipulated to establish high- and low-carp biomass treatments in each billabong. Measurements of benthic variables (rates of particle settlement, biofilm development, sediment respiration, macrophyte detritus decomposition, sediment solid-phase nutrient concentrations and benthic algal biomass) were performed over four months from summer to winter 1995. Rates of particle settlement were greater in the high-carp treatment of each billabong throughout the experiment. High carp biomass had a negative impact on the autotrophic component of the biofilm developing on wood blocks placed at different heights above the sediment surface but the mechanism responsible differed between billabongs. Sediment oxygen demand became greater in the presence of a higher biomass of carp during the experiment but time courses differed between billabongs. Manipulations of carp biomass did not influence algal biomass on the sediment surface, the rate of decomposition of macrophyte detritus or sediment solid-phase nutrients or nutrient ratios. The impact of carp on benthic and surficial processes was significant but the mechanisms of change differed between billabongs.

Impact of net pen aquaculture on lake water quality

2003 ◽  
Vol 47 (12) ◽  
pp. 293-300 ◽  
Author(s):  
J. Veenstra ◽  
S. Nolen ◽  
J. Carroll ◽  
C. Ruiz
Keyword(s):  
Water Quality ◽  
Organic Carbon ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
Ictalurus Punctatus ◽  
Oxygen Demand ◽  
Total Alkalinity ◽  
Total Hardness ◽  
Army Corps ◽  
Lake Water Quality

A 3-year study was conducted by the U.S. Army Corps of Engineers assessing water quality related impacts of aquaculture of 250,000 channel catfish (Ictalurus punctatus) in floating net pens in the Rock Creek Arm of Lake Texoma, Oklahoma/Texas. Five large nylon nets suspended from a floating framework of galvanized metal anchored in open water 100 m offshore made up the net pens with fish stocking densities varying from 88 to 219 fish/m3. Water quality sampling was conducted biweekly from April to September and monthly from October to March at three locations. On all sampling dates field measurements of water temperature, pH, dissolved oxygen, and conductivity were recorded at 1 m depth intervals and water samples were collected at a depth of 0.5 m and near the bottom of the water column at each site. Sample analyses included: total alkalinity, total hardness, turbidity, chloride, sulfate, orthophosphate, total phosphorus, nitrate-N, nitrite-N, total Kjeldahl nitrogen, total organic carbon, dissolved organic carbon, biochemical oxygen demand, and chlorophyll a. The results showed statistically significant decreases in water temperature and dissolved oxygen and significant increases in field conductivity in surface waters near the net pens relative to other sampling sites. The most dramatic water quality effect observed during the study was decrease in dissolved oxygen levels near the net pens following lake turnover in the second year.

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