Evolution of the Performances of Radar Altimetry Missions from ERS-2 to Sentinel-3A over the Inner Niger Delta

Normandin, Cassandra; Frappart, Frédéric; Diepkilé, Adama Telly; Marieu, Vincent; Mougin, E.; Blarel, Fabien; Lubac, Bertrand; Braquet, Nadine; Ba, Abdramane

doi:10.3390/rs10060833

Cited by 71 publications

(63 citation statements)

References 54 publications

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“…Time series of water levels based on the ICE-1 retracked ranges which provides accurate estimate of the height of the lake water bodies 56 , were derived using the Multi-mission Altimetry Processing Software (MAPS), that is commonly used for this purpose 58,59 . Details of the processing of the altimetry data in MAPS can be found in Normandin et al 60 . As already mentioned, only altimetry data from the 35-day repeat period missions are used, meaning that there are 11 values of water level per year per VS.…”

Section: Methodsmentioning

confidence: 99%

The Lake Chad hydrology under current climate change

Pham-Duc

Sylvestre

Papa

et al. 2020

Sci Rep

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112

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Lake Chad, in the Sahelian zone of west-central Africa, provides food and water to ~50 million people and supports unique ecosystems and biodiversity. In the past decades, it became a symbol of current climate change, held up by its dramatic shrinkage in the 1980s. Despites a partial recovery in response to increased Sahelian precipitation in the 1990s, Lake Chad is still facing major threats and its contemporary variability under climate change remains highly uncertain. Here, using a new multi-satellite approach, we show that Lake Chad extent has remained stable during the last two decades, despite a slight decrease of its northern pool. Moreover, since the 2000s, groundwater, which contributes to ~70% of Lake Chad’s annual water storage change, is increasing due to water supply provided by its two main tributaries. Our results indicate that in tandem with groundwater and tropical origin of water supply, over the last two decades, Lake Chad is not shrinking and recovers seasonally its surface water extent and volume. This study provides a robust regional understanding of current hydrology and changes in the Lake Chad region, giving a basis for developing future climate adaptation strategies.

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Section: Methodsmentioning

confidence: 99%

The Lake Chad hydrology under current climate change

Pham-Duc

Sylvestre

Papa

et al. 2020

Sci Rep

Self Cite

112

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“…We also use data from the Sentinel‐3A satellite that became operational in 2016. There is less than 3 years of data at the time of writing, and performance evaluation is limited, although a recent study on the Niger River reported improved performance of Sentinel‐3A compared with well‐established altimeters including ENVISAT (Normandin et al, ). However, it was operational during our field campaign so is of use for comparative purposes.…”

Section: Methods and Data Setsmentioning

confidence: 99%

Greater Water Surface Variability Revealed by New Congo River Field Data: Implications for Satellite Altimetry Measurements of Large Rivers

Carr

Trigg

Tshimanga

et al. 2019

Geophysical Research Letters

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Large river hydrodynamics studies inform global and regional issues pertaining to biogeochemical cycling, ecology, water availability, and flood risk. Such studies rely increasingly on satellite measurements, but these are limited by resolution, coverage, and uncertainty and their inability to directly measure bathymetry or discharge. We obtain new in situ data covering 650 km of the Congo's main stem, including elusive bathymetry and discharge measurements that complement space‐borne data sets. Our key findings relate to our water surface elevation measurements, which show that spatial coverage of existing satellite altimetry for deriving river water surface profiles may be adequate through the globally important Cuvette Centrale but is not at its outlet where our field data reveal significant spatial variability in water surface slope. The findings have implications for altimetry‐based hydrodynamics studies of other large rivers, such as those that involve estimating discharge or modeling multichannel river hydraulics.

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“…The IRWR data for Africa were acquired from the AQUASTAT database at (http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en). The lake level altimetry observations for four major African Lakes (Tana, Victoria, Malawi, and Tanganyika) and two reservoirs (Volta and Nasser) were obtained from the HYDROWEB portal (http://hydroweb.theia-land.fr/); noteworthy, these lake level altimetry observations have good agreement with in-situ water levels observations according to [37,53]. Additionally, through personal communications, we acquired the time series for the depth to groundwater for twenty observational wells in North Ghana from December 2005 to December 2012.…”

Section: Ancillary Datamentioning

confidence: 96%

Assessment of Physical Water Scarcity in Africa Using GRACE and TRMM Satellite Data

et al. 2019

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The critical role of water in enabling or constraining human well-being and socioeconomic activities has led to an interest in quantitatively establishing the status of water (in)sufficiency over space and time. Falkenmark introduced the first widely accepted measure of water status, the Water Scarcity Index (WSI), which expressed the status of the availability of water resources in terms of vulnerability, stress, and scarcity. Since then, numerous indicators have been introduced, but nearly all adopt the same basic formulation; water status is a function of “available water” resource—by the demand or use. However, the accurate assessment of “available water” is difficult, especially in data-scarce regions, such as Africa. In this paper, therefore, we introduce a satellite-based Potential Available Water Storage indicator, PAWS. The method integrates GRACE (Gravity Recovery and Climate Experiment) satellite Total Water Storage (TWS) measurements with the Tropical Rainfall Measuring Mission (TRMM) precipitation estimates between 2002 and 2016. First, we derived the countries’ Internal Water Storage (IWS) using GRACE and TRMM precipitation data. Then, the IWS was divided by the population density to derive the PAWS per capita. Following the Falkenmark thresholds, 54% of countries are classified in the same water vulnerability status as the AQUASTAT Internal Renewable Water Resources (IRWR) method. Of the remaining countries, PAWS index leads to one or two categories shift (left or right) of water status. The PAWS index shows that 14% (~160 million people) of Africa’s population currently live under water scarcity status. With respect to future projections, PAWS index suggests that a 10% decrease in future water resources would affect ~37% of Africa’s 2025 population (~600 million people), and 57% for 2050 projections (~1.4-billion people). The proposed approach largely overcomes the constraints related to the data needed to rapidly and robustly estimate available water resources by incorporating all stocks of water within the country, as well as underscores the recent water storage dynamics. However, the estimates obtained concern potential available water resources, which may not be utilizable for practical, economic, and technological issues.

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Evolution of the Performances of Radar Altimetry Missions from ERS-2 to Sentinel-3A over the Inner Niger Delta

Cited by 71 publications

References 54 publications

The Lake Chad hydrology under current climate change

The Lake Chad hydrology under current climate change

Greater Water Surface Variability Revealed by New Congo River Field Data: Implications for Satellite Altimetry Measurements of Large Rivers

Assessment of Physical Water Scarcity in Africa Using GRACE and TRMM Satellite Data

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