Water quality and phytoplankton dynamics in Moreton Bay, south-eastern Queensland. II. Mathematical modelling.

1998 ◽  
Vol 49 (3) ◽  
pp. 227 ◽  
Author(s):  
James McEwan ◽  
Albert J. Gabric ◽  
Peter R. F. Bell
Keyword(s):  
Water Quality ◽  
Field Data ◽  
Nutrient Loading ◽  
Light Availability ◽  
Population Pressure ◽  
Eastern Region ◽  
Nutrient Loads ◽  
Quality Model ◽  
Moreton Bay ◽  
European Settlement

A coupled hydrodynamic water-quality model of Moreton Bay was developed to enable better management of nutrient loads and to predict eutrophication-related problems. The hydrodynamic submodel was calibrated to available tidal data, and the transport submodel was calibrated to a salinity dataset. A 15-month time-series of field data was used together with historical data to calibrate and validate the water-quality submodel. Model simulations suggest that denitrification removes over half the external N inputs with about one-third exported to the open ocean. Approximately 8% of N and 20% of the P loading accumulates in the sediments. Short-term variations due to hydrodynamic effects tend to mask the seasonal cycle in phytoplankton biomass except at inshore localities. The model predictions confirm the field data that indicate that water quality in the western bay is severely affected while the better flushed eastern region remains relatively unaffected. Future increases in nutrient loading due to population pressure are predicted to extend the severely affected region eastwards. Over most of the bay, algal productivity is N-limited except for the western margins where nutrients are saturating and light availability regulates growth. Model hindcasts suggest that system-wide mean algal production has increased by a factor of ten since European settlement.

Water quality and phytoplankton dynamics in Moreton Bay, south-eastern Queensland. I. Field survey and satellite data

1998 ◽  
Vol 49 (3) ◽  
pp. 215 ◽  
Author(s):  
James McEwan ◽  
Albert J. Gabric ◽  
Peter R. F. Bell
Keyword(s):  
Water Quality ◽  
Nutrient Loading ◽  
Population Expansion ◽  
Water Clarity ◽  
Western Boundary ◽  
Nutrient Loads ◽  
Moreton Bay ◽  
South Eastern ◽  
Temporal And Spatial Variability ◽  
The Impact

The water quality of Moreton Bay, a sub-tropical estuarine embayment in south-eastern Queensland, was monitored over a 2-year period. Surveys in situ and ground-truthed satellite imagery were used to describe the temporal and spatial variability in water-quality indicators and the level of eutrophication. Strong east–west gradients in chlorophyll α and water clarity were found. During the study period fluvial discharges, which all enter on the western littoral, were below their long-term averages, and nutrient loading to the bay was dominated by point-source wastewater discharges along the western boundary. The data suggest that although the impact of nutrient loads on the bay’s eastern side is mitigated by tidal intrusion of oceanic water, the western areas are already degraded and can be considered mesotrophic to eutrophic. This part of the bay may deteriorate further with the projected future population expansion in the bay’s catchment.

Biology and Management of Inland Striped Bass and Hybrid Striped Bass

2013 ◽  
Keyword(s):  
Water Quality ◽  
South Carolina ◽  
Dissolved Oxygen ◽  
Striped Bass ◽  
Algal Blooms ◽  
Management Practices ◽  
Nutrient Loading ◽  
Phosphorus Loading ◽  
Quality Model ◽  
Habitat Temperature

<em>Abstract</em>.—A CE-QUAL-W2 water quality model was used to characterize the availability of striped bass <em>Morone saxatilis</em> habitat in Lake Greenwood, South Carolina, during 2004 and 2005. Although the lake has a productive fishery, water quality and aquatic habitat are affected by nutrient loading, algal blooms, and extensive oxygen depletion in the bottom waters. The main objectives were to characterize habitat availability and predict the implications of a change in phosphorus loading from the Saluda and Reedy rivers. The baseline scenario of the model showed that habitat was most critical during July and August, when as little of 5% of the reservoir contained tolerable habitat (temperature <28°C and dissolved oxygen >2 mg/L). Favorable habitat (temperature <25°C and dissolved oxygen >2 mg/L) was usually absent for most of July and August. Pulses of higher inflow or freshets produced short-term increases in tolerable habitat, especially in the upper end of the reservoir. Phosphorus-loading scenarios predicted that large reductions (50% or more) would be required to improve habitat substantially during midsummer. For the manager of a striped bass fishery, water quality models can be useful tools for evaluating habitat, especially under marginal conditions, and for predicting the impact of altered water management practices.

scholarly journals Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon

2017 ◽  
Vol 14 (19) ◽  
pp. 4423-4433 ◽  
Author(s):  
Yafei Zhu ◽  
Andrew McCowan ◽  
Perran L. M. Cook
Keyword(s):  
Water Quality ◽  
Primary Production ◽  
Total Phosphorus ◽  
Coastal Lagoon ◽  
Nutrient Dynamics ◽  
Nutrient Loading ◽  
Nitrogen Loading ◽  
Quality Model ◽  
Nitrogen Loads ◽  
Sediment Carbon

Abstract. The effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system (the Gippsland Lakes) were investigated using a 3-D coupled hydrodynamic biogeochemical water quality model. The study showed that primary production was equally sensitive to changed dissolved inorganic and particulate organic nitrogen loads, highlighting the need for a better understanding of particulate organic matter bioavailability. Stratification and sediment carbon enrichment were the main drivers for the hypoxia and subsequent sediment phosphorus release in Lake King. High primary production stimulated by large nitrogen loading brought on by a winter flood contributed almost all the sediment carbon deposition (as opposed to catchment loads), which was ultimately responsible for summer bottom-water hypoxia. Interestingly, internal recycling of phosphorus was more sensitive to changed nitrogen loads than total phosphorus loads, highlighting the potential importance of nitrogen loads exerting a control over systems that become phosphorus limited (such as during summer nitrogen-fixing blooms of cyanobacteria). Therefore, the current study highlighted the need to reduce both total nitrogen and total phosphorus for water quality improvement in estuarine systems.

Calculation and Analysis of Water Quality Improvement Caused by Water Diversion in Nanjing Qinhuai River

2012 ◽  
Vol 256-259 ◽  
pp. 2528-2532
Author(s):  
Chao Feng Tong ◽  
Li Rui Lv ◽  
Yu Yang Shao ◽  
Jia Ling Hao
Keyword(s):  
Water Quality ◽  
Nutrient Loading ◽  
Water System ◽  
Water Diversion ◽  
Middle Reach ◽  
Quality Model ◽  
One Dimensional ◽  
The Impact ◽  
Qinhuai River

To explore the impact of changes in water quality of the Nanjing Inner Qinhuai River water system in different water diversion way and to assess the transfer effect, an one-dimensional hydrodynamic and water quality model for Inner Qinhuai River was established to simulate and analysis the responds of water quality on the different nutrient loading and different diverted water. Four different water discharges diverted from Xuanwu Lake and Exterior Qinhuai River and two loads including the present load and 50% reduction were considered. The result shows the water quality can be improved significantly only as enough water is diverted and the sewage is intercept in the Middle Reach of the Inner Qinhuai River.

scholarly journals Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon

2017 ◽  
Author(s):  
Yafei Zhu ◽  
Andrew McCowan ◽  
Perran L. M. Cook
Keyword(s):  
Water Quality ◽  
Coastal Lagoon ◽  
Nutrient Dynamics ◽  
Nutrient Loading ◽  
Phosphorus Release ◽  
Nitrogen Loading ◽  
Quality Model ◽  
Nitrogen Loads ◽  
Almost All ◽  
Sediment Carbon

Abstract. The effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system (the Gippsland Lakes) was investigated using a 3D coupled hydrodynamic biogeochemical water quality model. The study showed that primary productivity was equally sensitive to changed dissolved inorganic and particulate organic nitrogen loads, highlighting the need for a better understanding of particulate organic matter bioavailability. Stratification and sediment carbon enrichment are the main drivers for the hypoxia and subsequent sediment phosphorus release in the Lake King. High primary production stimulated by large nitrogen loading brought by winter flood contributed almost all the sediment carbon deposition (as opposed to catchment loads) which was ultimately responsible for summer bottom-water hypoxia. Interestingly, internal recycling of phosphorus was more sensitive to changed nitrogen loads than total phosphorus loads, highlighting the potential importance of nitrogen loads exerting a control over systems that become phosphorus limited (such as during summer nitrogen-fixing blooms of cyanobacteria). Therefore, the current study highlighted the need to reduce both TN and TP for water quality improvement in estuarine systems.

Water quality modeling to evaluate BMPs in rice paddies

2006 ◽  
Vol 53 (2) ◽  
pp. 253-261 ◽  
Author(s):  
J.H. Jeon ◽  
C.G. Yoon ◽  
H.S. Hwang ◽  
K.W. Jung
Keyword(s):  
Water Quality ◽  
Best Management Practices ◽  
Nutrient Concentration ◽  
Management Practices ◽  
Nutrient Loading ◽  
Water Quality Modeling ◽  
Rice Paddies ◽  
Quality Model ◽  
Dirac Delta ◽  
Surface Drainage

A water quality model applicable to rice paddies was developed using field data from 1999–2002. Use of the Dirac delta function efficiently explained the nutrient-concentration characteristics of ponded water. The model results agreed reasonably well with the observed data. The ponded-water quality was influenced primarily by fertilization; nutrient concentration was especially high during early cultivation periods. Reducing surface drainage during the fertilization period may substantially reduce nonpoint source loading from paddies. Increased weir heights and shallow irrigation methods were evaluated by the model as practical methods for reducing nutrient loading from paddies. These methods were effective in reducing surface drainage and are suggested as “best management practices” (BMPs) if applied based on site-specific paddy conditions.

Mitigating Impacts of Natural Hazards on Fishery Ecosystems

2008 ◽  
Keyword(s):  
Water Quality ◽  
Nutrient Loading ◽  
Water Quality Management ◽  
River Estuary ◽  
Chemical Properties ◽  
Neuse River Estuary ◽  
Estuarine System ◽  
Nutrient Loads ◽  
Habitat Alterations ◽  
The Past

<em>Abstract</em>.—Since the mid-1990s, the U.S. mid-Atlantic region has witnessed a sudden rise in hurricane and tropical storm landfalls. In particular, eastern North Carolina has been impacted by eight hurricanes and six tropical storms in the past decade, and this relatively high frequency is forecast to continue for the next several decades. Each of the past storms exhibited unique hydrologic and nutrient loading scenarios for the Pamlico Sound, the United States’ second largest estuarine system and its largest subestuary, the Neuse River estuary. This variability represents a challenge to nutrient management aimed at protecting water quality and ensuring optimal fisheries habitat conditions. Different rainfall amounts among hurricanes led to variable freshwater and nutrient discharge and hence variable nutrient, organic matter, and sediment enrichment. These enrichments differentially affected physical and chemical properties (salinity, water residence time, transparency, stratification, dissolved oxygen), phytoplankton primary production, and phytoplankton community composition. The contrasting effects were accompanied by biogeochemical perturbations (hypoxia, enhanced nutrient cycling), benthic and planktonic habitat alterations, and possibly food web disturbances. Floodwaters from the two largest hurricanes, Fran (1996) and Floyd (1999), exerted multimonth to multiannual effects on hydrology, nutrient loads, productivity, biotic composition, and habitat condition. In contrast, relatively low rainfall coastal hurricanes like Isabel (2003) and Ophelia (2005) caused strong vertical mixing and storm surges but exhibited relatively minor hydrologic, nutrient, and biotic impacts. Both hydrologic and wind forcing are important drivers and must be integrated with nutrient loading in assessing short- and long-term ecological impacts of these storms. These climatic forcings cannot be managed but must be considered when developing water quality management strategies for these and other large estuarine ecosystems faced with increasing frequencies and intensities of hurricane activity.

scholarly journals Changes in land use in the buffer zone of lake of the Mała Wełna catchment

2012 ◽  
Vol 12 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Mariusz Ptak ◽  
Agnieszka E. Ławniczak
Keyword(s):  
Water Quality ◽  
Land Use ◽  
Nutrient Loading ◽  
Lake Management ◽  
Buffer Zone ◽  
Nutrient Loads ◽  
Buffer Zones ◽  
Nutrient Sources ◽  
Forested Areas ◽  
Water Pollutant

Abstract One of the most important elements in the protection of water quality is buffer zones. In order to protect water quality, appropriate management of these areas is necessary. In the paper, changes in the land use in the buffer zone of 200 m width around lakes in the Mała Wełna catchment over 20 years were analysed. For the study eight lakes larger than 50 ha were chosen. Changes in the land use within the buffer zone were studied from 1980 to 2000, based on topographic maps in the scale 1:10 000. Results show both positive and negative aspects of land changes. An increase in forested areas and grasslands through tilled land were positive aspects of these changes. On the other hand, the enhancement of suburban development in these zones caused increased probability of water pollution from these areas. Calculations of potential nutrient loading from different types of land use in these zones indicated an enhancement of nutrient sources in the lakes within the 20-year study period. However, these changes are not significant in comparison to the nutrient loads contributed by the tributaries. Our study indicated that in the case of flow lakes, more important is an improvement in water quality in the tributaries and a reduction in nutrient sources in the catchment with the purpose of reducing the input of nutrients into the lake. Management of the buffer zone is one of the issues which have to be taken into consideration in lake protection after elimination of the major water pollutant sources.

scholarly journals Assessing Water and Nutrient Long-Term Dynamics and Loads in the Enxoé Temporary River Basin (Southeast Portugal)

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 354 ◽  
Author(s):  
David Brito ◽  
Ramiro Neves ◽  
Maria Branco ◽  
Ângela Prazeres ◽  
Sara Rodrigues ◽  
...  
Keyword(s):  
Algal Blooms ◽  
Field Data ◽  
Trophic State ◽  
Assessment Tool ◽  
Geometric Mean ◽  
Light Availability ◽  
Nutrient Loads ◽  
Management Scenarios ◽  
High Concentrations

The Enxoé reservoir has been exhibiting frequent high chlorophyll-a concentrations (reaching a geometric mean six times the national limit for eutrophication of 10 μg L−1) since 2000, and represents the reservoir with the highest eutrophic state in Portugal. Toxic algal blooms have also been observed, which pose serious challenges to water managers, as the reservoir is used for potable water production. In an effort to contribute to the reduction of the reservoir trophic state, the watershed inputs (monthly flows, sediment, nitrogen (N) and phosphorus (P) loads) were characterized with the Soil Water Assessment Tool (SWAT). Field data were collected in the ungauged watershed during 2010 and 2011. Model results were then used to characterize the long-term watershed dynamics in terms of water and nutrients. SWAT estimates of the simulated flow, and the sediment and nutrient loads were in good agreement with field data (R2 between 0.42–0.78; Nash-Sutcliffe efficiencies between 0.19–0.75). The Enxoé River was characterized by a temporary flushy regime where high concentrations were transported in short time periods. As a result, nutrient loads delivered to the Enxoé reservoir were estimated to be 18 tonN year−1 and 0.7 tonP year−1 (30 years’ simulation), reaching the reservoir mainly by runoff. These results were consistent with the gentle slopes, extensive agricultural activities, and low urban pressure observed in Enxoé. The magnitude of the nutrient exports suggests that the reservoir eutrophication may also be linked to the reservoir geometry (average depth of 5 m), which provides high light availability to the bottom sediments. Thus, SWAT results were integrated into a reservoir model to depict the origin of the Enxoé trophic state and test management scenarios that may reduce it.

scholarly journals A coupled model of hydrodynamics circulation and water quality applied to the Rio Verde reservoir, Brazil

2018 ◽  
Vol 13 (6) ◽  
pp. 1
Author(s):  
Cynara De Lourdes da Nobrega Cunha ◽  
Gabriela Pacheco Corrêa ◽  
Paulo Cesar Colonna Rosman
Keyword(s):  
Water Quality ◽  
Field Data ◽  
Coupled Model ◽  
Circulation Model ◽  
Quality Parameters ◽  
Water Quality Model ◽  
Quality Model ◽  
Data Set ◽  
Passive Scalars ◽  
Model Flow

This work applied the coupled horizontal two-dimensional hydrodynamic circulation model (2DH) and the vertically integrated water quality model for non-conservative and passive scalars to the Rio Verde reservoir in the state of Paraná, Brazil, to simulate flow, temperature and water quality parameters. The water quality model uses the same spatial grid applied for the hydrodynamics model. Flow velocities and turbulence coefficients previously defined in the hydrodynamics model can be used directly in the water quality model. Modeling results were compared to field data for a period of 308 days, from February 27th 2010 and December 31th 2010. Field data included water and air temperature, wind, relative humidity, radiation, discharges and concentration values of some substances in the tributaries of the reservoir. The results indicated that hydrodynamic circulation and, consequently, horizontal transport, are strongly dependent on the wind. Inflows/outflows generated a localized circulation. The results for the temperature and dissolved oxygen concentration were compared with field measures and a satisfactory consistency was achieved. Despite the errors associated with boundary conditions, the models demonstrated their potential to adequately simulate the data set collected from the reservoir.

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