Processes affecting horizontal mixing and dispersion in Winam Gulf, Lake Victoria

Okely, Patricia; Imberger, Jö rg; Antenucci, Jason P.

doi:10.4319/lo.2010.55.5.1865

Cited by 41 publications

(51 citation statements)

References 53 publications

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“…average RMSE of 0.66 • C (∼ 13 % of the range). This level of accuracy is consistent with other 3-D modeling studies of lakes (Hodges et al, 2000;Okely et al, 2010). The error analysis of the simulated water level near the dam also produced favorable results, indicating that the EL-COM model could accurately compute the water balance and represent the reduction in the water level during the simulation period.…”

Section: Sensitivity Analysis and Validationsupporting

confidence: 86%

“…Three-dimensional (3-D) models are complementary and efficient approaches that have been widely used for understanding physical and biological processes in lakes and reservoirs (Bonnet and Wessen, 2001;Hodges et al, 2002;Vidal et al, 2007;Rueda and MacIntyre, 2009;Okely et al, 2010). One of the main advantages of 3-D models is the possibility to simulate real and hypothetical scenarios, as well as the ability to simulate various processes simultaneously.…”

Section: P Curtarelli Et Al: Physical Changes Within a Large Tromentioning

confidence: 99%

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Physical changes within a large tropical hydroelectric reservoir induced by wintertime cold front activity

Curtarelli

Alcântara

Rennó

et al. 2014

Hydrol. Earth Syst. Sci.

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Abstract. We investigated the influence of wintertime cold front activity on the physical processes within a large tropical reservoir located in Brazil. The period chosen for this study consisted of 49 days between 28 April 2010 and 15 July 2010. This period was defined based on information from the Brazilian Center for Weather Forecasting and Climate Studies (CPTEC), data collected in situ and the interpretation of remotely sensed images. To better understand the governing processes that drive changes in the heat balance, differential cooling and mixing dynamics, a simulation was performed that utilized a three-dimensional hydrodynamic model enforced with in situ and remote sensing data. The results showed that during a cold front passage over the reservoir, the sensible and latent heat fluxes were enhanced by approximately 77 and 16 %, respectively. The reservoir's daily averaged heat loss was up to 167 % higher on the days with cold front activity than on the days without activity. The cold front passage also intensified the differential cooling process; in some cases the difference between the water temperature of the littoral and pelagic zones reached up to 8 • C. The occurrence of cold front passages impacted the diurnal mixed layer (DML), by increasing the turbulent energy input (∼ 54 %) and the DML depth (∼ 41 %). Our results indicate that the cold front events are one of the main meteorological disturbances driving the physical processes within hydroelectric reservoirs located in tropical South America during the wintertime. Hence, cold front activity over these aquatic systems has several implications for water quality and reservoir management in Brazil.

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Section: Sensitivity Analysis and Validationsupporting

confidence: 86%

Section: P Curtarelli Et Al: Physical Changes Within a Large Tromentioning

confidence: 99%

Physical changes within a large tropical hydroelectric reservoir induced by wintertime cold front activity

Curtarelli

Alcântara

Rennó

et al. 2014

Hydrol. Earth Syst. Sci.

View full text Add to dashboard Cite

show abstract

“…Compared to typical situations in stratified lakes [1,7,18,31,35], the effects of lake stratification and of the river-lake density difference are of minor importance for the inflow intrusion into Lake Tegel. Nevertheless, the combined effects of the river discharge, wind direction and lake morphometry result in highly variable intrusion rates.…”

Section: Discussionmentioning

confidence: 97%

“…However, the mechanisms governing the distribution of inflow waters across the lake remain unresolved, and the contributions of wind and river discharge as drivers of mixing are unknown. Numerical modeling of lake hydrodynamics is a reliable tool to investigate these effects [1,18]. Below, we apply a two-dimensional hydrodynamic circulation model including conservative tracer transport to Lake Tegel.…”

mentioning

confidence: 99%

Effects of wind-driven circulation on river intrusion in Lake Tegel: modeling study with projection on transport of pollutants

et al. 2012

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Prediction of mixing intensity of water masses in riverine Lake Tegel (Berlin, Germany) can be used to trace the fate of pollutants that enter the lake through several inflows. Because the contributions of each inflow have not yet been quantified and because the lake features complex bathymetry and numerous islands, a hydrodynamic circulation model with high spatial resolution and dynamic wind forcing is useful. We applied the two-dimensional version of the Princeton Ocean Model to separate the influences of wind and river discharge on the currents and mass transport in Lake Tegel. For model validation, we compared the simulation results with 1 year of electrical conductivity data, which was used as a conservative tracer to distinguish between water from the River Havel and water supplied by a smaller second inflow. Calculation of currents alone is insufficient to investigate water exchanges between rivers and lakes, especially when several islands create multiple pathways for river intrusion. Therefore, mass transport simulations are applied. Our calculations based on archetypical scenarios indicate that the proportion of (polluted) water from the River Havel in the main basin of Lake Tegel fluctuates with river discharge and wind, which either amplify or neutralize each other.

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“…the northeast of Lake Victoria (~40 m depth) through the Rusinga Channel (Okely et al 2010). Sampling stations spanning the Gulf and Channel (Fig.…”

Section: Alexander Et Almentioning

confidence: 99%

Identifying spatial structure in phytoplankton communities using multi‐wavelength fluorescence spectral data and principal component analysis

Alexander

Gikuma-Njuru

Imberger

2012

Limnology & Ocean Methods

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Rapid in situ measurements of some components of fluorescent spectra are now possible with submersible multi-wavelength fluorometers, which implies that phytoplankton composition can be measured, at least implicitly, at a spatial resolution that allows many scales of patches to be resolved. We present a method for identifying the location of patches of distinct fluorescent groupings of phytoplankton by using principal component analysis (PCA) to process in situ spectral data. The processing method potentially allows retention of more information from the raw data than existing methods because it depends on fewer assumptions. Furthermore, it can be applied without the need for site-specific calibration of the fluorometer. A series of idealized spectral data sets were used to explain the conceptual basis of the approach; the method was then applied to field spectral data sampled in Lake Victoria, Kenya. The results demonstrate that the main features of large sample sets of multi-component spectral data can be summarized in a single graph that reveals the number of spectrally distinct groups of phytoplankton at the site, and allows information about the spatial structure of those different phytoplankton groups to be derived from subsequent analysis. In this way, fluorescent spectral data collected at high spatial resolution can be used to identify the locations of patches and facilitate targeted water sample collection from those locations to investigate the species diversity and distribution at a study site.

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Processes affecting horizontal mixing and dispersion in Winam Gulf, Lake Victoria

Cited by 41 publications

References 53 publications

Physical changes within a large tropical hydroelectric reservoir induced by wintertime cold front activity

Physical changes within a large tropical hydroelectric reservoir induced by wintertime cold front activity

Effects of wind-driven circulation on river intrusion in Lake Tegel: modeling study with projection on transport of pollutants

Identifying spatial structure in phytoplankton communities using multi‐wavelength fluorescence spectral data and principal component analysis

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