A review and update of the hydrology of Lake Victoria in East Africa

Abstract

Water balance models have been used to examine trends in the level of Lake Victoria over this century. A monthly model developed in a previous study for the period 1925 to 1978 has been improved and the simulation period extended to 1990. Also, an annual model has been used to extend the water balance back to the start of the century. The simulations confirm the results from previous studies which showed that the observed variations in lake level can be explained primarily in terms of natural variations in rainfall over the lake and surrounding basin. An idealized interpretation of these variations is presented which illustrates the long response time of this large lake and which is used to speculate on the likely future behaviour of the lake.

Natural climatic changes and solar cycles: an analysis of hydrological time series

“…Continuing the analysis of historical data sets, the rise in water levels of Lake Victoria (Equator) which occurred at the beginning of the 1960s, explained by rainfall variation in the catchment area (Sene & Plinston, 1994), can be seen to coincide with a marked increase in the discharges of the River Po recorded over the winter period (45°N) and with an increase in the hydrological variability in rainfall and discharges (runoff) in north central England (55°N) (Burt et al, 1998). A linear correlation was found equal to 0.39 with a significance level of 98% between the series of River Po discharges and the ratios between winter rainfalls (DJF) and summer rainfalls (JJA) at Durham, UK (Fig.…”

Theoretical estimates for the influence of Lake Victoria on flows in the upper White Nile

“…The transient response is important when considering the influence of sudden changes in level due to localized rainfall, such as the major increase which occurred during three unusually wet years in East Africa in the early 1960s, and which has been reported in detail in several previous papers (e.g. Kite, 1981;Piper et al, 1986;Sene & Plinston, 1994).…”

“…Kite, 1981;Sutcliffe & Parks, 1999). Owing to the huge surface area of the lake, small natural variations in rainfall have a major influence on the lake outflow, and hence on flows into the other lakes further downstream (Piper et al, 1986;Sene & Plinston, 1994). Another notable feature is that many of these flow variations are compensated for by changes in the surface area, and hence evaporation losses, in the Sudd swamps, with the result that the annual flow out of these swamps has remained almost constant for long periods during the observational record despite large variations in inflows.…”

Water balance of Lake Victoria: update to 2000 and climate change modelling to 2100 / Bilan hydrologique du Lac Victoria: mise à jour jusqu’en 2000 et modélisation des impacts du changement climatique jusqu’en 2100

“…The key to the whole procedure is the Lake Victoria direct rainfall series, developed by Sene & Plinston (1994). Using the lake system as a giant raingauge during years when the other factors were known, a relationship was obtained between rainfall at the long-term lakeside stations and net rainfall over the lake, which was then applied up to 1990.…”

“…They used rainfall records from gauges around the lake shore and completed a tributary inflow record using ratios to other gauged records, then extended the series back to 1925 using a net rainfall-soil moisture model. Sene & Plinston (1994) used two new water balance models to extend the modelling period to 1990 and to investigate trends in levels and outflows in the later years. They concluded that levels have remained relatively high since the early 1960s due to a sustained increase in lake rainfall.…”