20 Remote Sensing of African Lakes: A Review
409
Using data from the first 21 months of the TOPEX/Poseidon mission (September
1992–May 1994), Birkett (1995) estimated lake levels for climate sensitive lakes
including the following African lakes: Chad, Kariba, Malawi, Nasser, Tana, Tanganyika, Turkana, Victoria and Volta. Field data were used to estimate the accuracy
as ∼ 4 cm rms, thereby demonstrating the usefulness of satellite altimetry for lake
level measurement. Merceir et al. (2002) used TOPEX/Poseidon data from 1993
to 1999 to look at the same lakes as Birkett (1995) as well as Kyoga, Mweru and
Rukwa. They showed links between lake levels and the atmosphere over the Indian
Ocean.
Ricko (2011) used lake level data from the LEGOS (2013) dataset for lakes Bangweulu, Chad, Kainji, Malawi, Mweru, Tana, Tanganyika and Turkana as part of a
broader study of the effects of climate on tropical lake levels. Munyaneza et al.
(2009) used Envisat and ERS-2 from ESA (2013) for water level monitoring of Lake
Kivu. Velpuri et al. (2012) used TOPEX/Poseidon, Jason-1 and Envisat from USDA
(2013) for validation of hydrological models for Lake Turkana.
Lake Chad has also drawn much interest. Birkett (2000) used TOPEX/Poseidon
along with AVHRR to examine variability of basin inundation. Coe and Birkett
(2004) used TOPEX/Poseidon along with ground-based information to estimate river
discharge and lake level. In a review paper, Crétaux and Birkett (2006) noted that
TOPEX/Poseidon data for Lake Chad were reported to have lower accuracy (tens
of cm) compared with other lakes such as the Laurentian Great Lakes (a few cm).
Turada (2008) used TOPEX/Poseidon derived levels from USDA (2013) to confirm
MERIS-based areal extent changes. Lemoalle et al. (2012) used previous altimetric
work as input for a hydrological model to examine management options for Lake
Chad.
Finally, altimetric sensing has often played a key role in gravimetric approaches.
Swenson and Wahr (2009) used lake level data from USDA (2013) for Lake Victoria, LEGOS (2013) data for lakes Albert, Edward and Kyoga, and data from Ice,
Cloud, and land Elevation Satellite (ICESat), part of NASA’s Earth Observing System (EOS), of later periods for Kyoga. They used altimetric data to show that excess
water input to Lake Victoria since mid-2007 has been used for hydropower generation
and not stored for future drought relief. Additionally, Lake Kyoga levels were shown
to reflect an increase in discharge from Lake Victoria despite a regional drought. Additionally, Becker et al. (2010) used ESA (2013), LEGOS (2013) and USDA (2013)
altimetric data along with data from the Gravity Recovery And Climate Experiment
(GRACE), a joint mission of NASA and the German Aerospace Center, and precipitation data to study the recent hydrological behavior of Lakes Malawi, Tanganyika,
Turkana and Victoria.
20.3.2 Gravimetric Sensing
The launch of the twin GRACE sensors in 2002 added gravimetry, a nonelectromagnetic radiation based form of remote sensing, to the options available.
Differences in mass on earth can be detected by examining small changes in the
distance between the orbiting GRACE sensors as they pass over a given point. With
409
Using data from the first 21 months of the TOPEX/Poseidon mission (September
1992–May 1994), Birkett (1995) estimated lake levels for climate sensitive lakes
including the following African lakes: Chad, Kariba, Malawi, Nasser, Tana, Tanganyika, Turkana, Victoria and Volta. Field data were used to estimate the accuracy
as ∼ 4 cm rms, thereby demonstrating the usefulness of satellite altimetry for lake
level measurement. Merceir et al. (2002) used TOPEX/Poseidon data from 1993
to 1999 to look at the same lakes as Birkett (1995) as well as Kyoga, Mweru and
Rukwa. They showed links between lake levels and the atmosphere over the Indian
Ocean.
Ricko (2011) used lake level data from the LEGOS (2013) dataset for lakes Bangweulu, Chad, Kainji, Malawi, Mweru, Tana, Tanganyika and Turkana as part of a
broader study of the effects of climate on tropical lake levels. Munyaneza et al.
(2009) used Envisat and ERS-2 from ESA (2013) for water level monitoring of Lake
Kivu. Velpuri et al. (2012) used TOPEX/Poseidon, Jason-1 and Envisat from USDA
(2013) for validation of hydrological models for Lake Turkana.
Lake Chad has also drawn much interest. Birkett (2000) used TOPEX/Poseidon
along with AVHRR to examine variability of basin inundation. Coe and Birkett
(2004) used TOPEX/Poseidon along with ground-based information to estimate river
discharge and lake level. In a review paper, Crétaux and Birkett (2006) noted that
TOPEX/Poseidon data for Lake Chad were reported to have lower accuracy (tens
of cm) compared with other lakes such as the Laurentian Great Lakes (a few cm).
Turada (2008) used TOPEX/Poseidon derived levels from USDA (2013) to confirm
MERIS-based areal extent changes. Lemoalle et al. (2012) used previous altimetric
work as input for a hydrological model to examine management options for Lake
Chad.
Finally, altimetric sensing has often played a key role in gravimetric approaches.
Swenson and Wahr (2009) used lake level data from USDA (2013) for Lake Victoria, LEGOS (2013) data for lakes Albert, Edward and Kyoga, and data from Ice,
Cloud, and land Elevation Satellite (ICESat), part of NASA’s Earth Observing System (EOS), of later periods for Kyoga. They used altimetric data to show that excess
water input to Lake Victoria since mid-2007 has been used for hydropower generation
and not stored for future drought relief. Additionally, Lake Kyoga levels were shown
to reflect an increase in discharge from Lake Victoria despite a regional drought. Additionally, Becker et al. (2010) used ESA (2013), LEGOS (2013) and USDA (2013)
altimetric data along with data from the Gravity Recovery And Climate Experiment
(GRACE), a joint mission of NASA and the German Aerospace Center, and precipitation data to study the recent hydrological behavior of Lakes Malawi, Tanganyika,
Turkana and Victoria.
20.3.2 Gravimetric Sensing
The launch of the twin GRACE sensors in 2002 added gravimetry, a nonelectromagnetic radiation based form of remote sensing, to the options available.
Differences in mass on earth can be detected by examining small changes in the
distance between the orbiting GRACE sensors as they pass over a given point. With