Exploratory studies into seasonal flow forecasting potential for large lakes

Sene, Kevin; Tych, Włodek; Beven, Keith

doi:10.5194/hess-22-127-2018

Cited by 14 publications

(11 citation statements)

References 53 publications

(62 reference statements)

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“…turing the lake precipitation, as precipitation on the lake is enhanced compared to the surrounding land by the presence of the lake itself (Thiery et al, 2015;Sene et al, 2018). Previous WB studies accounted for this by rescaling onshore measured precipitation based on a relationship obtained by solving the WB for precipitation in a period when all other terms were known (Piper et al, 1986;Sene and Plinston, 1994;Tate et al, 2004), or by calculating lake precipitation from basin precipitation with a weighting factor based on a satellite analysis of cloud occurrence (Yin and Nicholson, 1998).…”

Section: Precipitation On the Lakementioning

confidence: 99%

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Modelling the water balance of Lake Victoria (East Africa) – Part 1: Observational analysis

Vanderkelen

Lipzig

Thiery

2018

Hydrol. Earth Syst. Sci.

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Abstract. Lake Victoria is the largest lake in Africa and one of the two major sources of the Nile river. The water level of Lake Victoria is determined by its water balance, consisting of precipitation on the lake, evaporation from the lake, inflow from tributary rivers and lake outflow, controlled by two hydropower dams. Due to a scarcity of in situ observations, previous estimates of individual water balance terms are characterized by substantial uncertainties, which means that the water balance is often not closed independently. In this first part of a two-paper series, we present a water balance model for Lake Victoria, using state-of-the-art remote sensing observations, high-resolution reanalysis downscaling and outflow values recorded at the dam. The uncalibrated computation of the individual water balance terms yields lake level fluctuations that closely match the levels retrieved from satellite altimetry. Precipitation is the main cause of seasonal and interannual lake level fluctuations, and on average causes the lake level to rise from May to July and to fall from August to December. Finally, our results indicate that the 2004–2005 drop in lake level can be about half attributed to a drought in the Lake Victoria Basin and about half to an enhanced outflow, highlighting the sensitivity of the lake level to human operations at the outflow dam.

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Section: Precipitation On the Lakementioning

confidence: 99%

“…Since then, the outflow is regulated by the Agreed Curve, a rating curve relating lake level and outflow in natural conditions. This relation is quantified by Sene (2000) as…”

Section: Lake Outflowmentioning

confidence: 99%

Modelling the water balance of Lake Victoria (East Africa) – Part 1: Observational analysis

Vanderkelen

Lipzig

Thiery

2018

Hydrol. Earth Syst. Sci.

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“…The East African rainfall is dominated by the El Nino-Southern Oscillation (ENSO) and annual rainfall is distributed over the lake by the movement of the Inter-Tropical Convergence Zone (ITCZ) (Kite, 1982;Smith & Semazzi, 2014). Lake outflow and water level are easily measured, but lake inflow, precipitation, and evaporation are difficult to measure or estimate (Sene, Tych, & Beven, 2018). The onshore rain measured precipitation data were enhanced compared to the surrounding land by the presence of the lake itself (Sene et al, 2018;Thiery et al, 2015).…”

Section: Uncertainty In Data Sourcesmentioning

confidence: 99%

“…Lake outflow and water level are easily measured, but lake inflow, precipitation, and evaporation are difficult to measure or estimate (Sene, Tych, & Beven, 2018). The onshore rain measured precipitation data were enhanced compared to the surrounding land by the presence of the lake itself (Sene et al, 2018;Thiery et al, 2015). Evaporation is very sensitive to air humidity on the lake and near-shore surface (Kite, 1981;Piper et al, 1986;Sene & Plinston, 1994;Smith & Semazzi, 2014;Tate et al, 2004), whereas the air temperature in the tropics are nearly constant and well measured.…”

Section: Uncertainty In Data Sourcesmentioning

confidence: 99%

Hydro-meteorological processes driving solute transport in Lake Victoria

Paul

Oppelstrup

2020

Water Science

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This study explores by a vertically integrated tracer transport model, hydro-meteorological event characteristics and their influence on solute transport. Changes in Hydro-meteorological processes and increasing frequency of extreme weather events are responsible for changing the lake water balance, influencing streamflow variations, and lake tracer transport. We compare historical data over a long time with model data from a vertically integrated model in COMSOL Multiphysics. We consider water balance, sources of data uncertainty, correlations, extreme rain and inflow years, and seasonal variations. The lake transport model has estimated soluble loading and transportation. The results showed there are strong correlations between tributary inflows and precipitation, and between lake outflow and water level. It was found that "events" influence lake level fluctuations. The solute transport was shown to vary more in wet periods. Modeled transportations were higher in Kenya and Uganda lake zones than in Tanzanian zones. The major inflow, from the Kagera river, appears to strongly influence lake solute transportation, so the composition of this river must be considered. ARTICLE HISTORY

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“…Onshore rain gauges are not capable to fully capture the lake precipitation, as precipitation on the lake is 10 enhanced compared to the surrounding land by the presence of the lake itself (Thiery et al, 2015;Sene et al, 2018). Previous 3 Hydrol.…”

Section: Precipitation On the Lakementioning

confidence: 99%

Modelling the water balance of Lake Victoria (East Africa) – Part 1: Observational analysis

Vanderkelen¹,

Lipzig²,

Thiery³

2018

Preprint

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Abstract. Lake Victoria is the largest lake in Africa and one of the two major sources of the Nile River. The water level of Lake Victoria is determined by its water balance, consisting of precipitation on the lake, evaporation from the lake, inflow from tributary rivers and lake outflow, controlled by two hydropower dams. Due to scarcity of in-situ observations, previous estimates of individual water balance terms are characterised by substantial uncertainties, which makes that the water balance is often not closed independently. Here we present a water balance model for Lake Victoria, using state-of-the-art remote sensing Precipitation is the main cause of seasonal and inter-annual lake level fluctuations, and on average causes the lake level to rise from May to July and to fall from August to December. Finally, our results indicate that the 2004-2005 drop in lake level can be attributed about half to a drought in the Lake Victoria Basin and about half to an enhanced outflow, highlighting the sensitivity 10 of the lake level to human operations at the outflow dam.

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Exploratory studies into seasonal flow forecasting potential for large lakes

Cited by 14 publications

References 53 publications

Modelling the water balance of Lake Victoria (East Africa) – Part 1: Observational analysis

Modelling the water balance of Lake Victoria (East Africa) – Part 1: Observational analysis

Hydro-meteorological processes driving solute transport in Lake Victoria

Modelling the water balance of Lake Victoria (East Africa) – Part 1: Observational analysis

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