Current availability and distribution of Congo basin's freshwater resources

Abstract

The Congo Basin is of global significance for biodiversity and the water and carbon cycles. However, its freshwater availability remains highly unknown. Here, we leverage a new method to characterize the relationship between drainable water storage and river discharge across the entire basin. We estimate that the Congo Basin currently holds 481±24 km³ of Total Drainable Water Storage, unevenly distributed throughout the region, with 68% being stored in the southernmost sub-basins, Kasaï (227±17 km³) and Lualaba (146±7 km³), while the northern sub-basins contribute only 173±8 km³. We further estimate the time constant for draining its entire water storage to be 4.3±0.4 month, but, regionally, large lakes act as resistors resulting in greater time constants of up to 105±3 month. Our estimate provides a robust basis to address the challenges of water demand for 120 million inhabitants, a population expected to double in a few decades.

A long-term monthly surface water storage dataset for the Congo basin from 1992 to 2015

“…The temporal variation of SWH is retrieved according to the repeat cycle of the satellite (Da Silva et al, 2010;Cretaux et al, 2017), cycle that varies from ten to twenty-seven days for current operational 180 satellites. Several studies, including Frappart et al (2006), Da Silva et al (2010), Papa et al (2010Papa et al ( , 2015, Kao et al (2019), Kittel et al (2021), Paris et al (2022), and Kitambo et al (2022), to name a few, have been conducted in different river basins to validate SWH variations against in situ water levels. Results generally show a good capability of radar altimeter to retrieve SWH variability with uncertainties ranging from a few centimeters to tens of centimeters, depending on the acquisition mode of the satellite and the environment characteristics (Bogning 185 et al, 2018;Normandin et al, 2018;Jiang et al, 2020;Kittel et al, 2021;Kitambo et al, 2022a).…”

“…Over CRB, Kitambo et al (2022) used ~2300 VSs from different satellite missions and their pooling based on the principle of the nearest neighbor (located at a minimum distance of 2 km, see Da Silva et al, 2010;Cretaux et al, 2017) to generate long-term time series with records lengths ranging from 12 to 25 years records (Fig. 2d of Kitambo et al, 2022a).…”

“…The information derived from SWS will therefore be very pertinent as a benchmark product regarding the calibration/validation of the future hydrology-oriented Surface Water and Ocean Topography (SWOT) satellite mission, to be launched at the end of 2022, which will provide water storage 675 variability of water bodies globally (Biancamaria et al, 2016). Additionally, SWS estimates provide a unique opportunity for future hydrological or climate modeling and to evaluate regional hydrological models (Scanlon et al, 2019) that still lack proper representation of surface water storage variability at large scale (Paris et al, 2022), especially in major African river basins (Papa et al, 2022).…”

Remote sensing of rivers: applications for streamflow and carbon flux estimations

“…The Amazon and Congo are the two largest rivers in the world, making them critical freshwater resources and major exporters of water to the oceans. The climate of equatorial regions includes high temperatures, humidity, and precipitation Tourian et al, 2023). The six largest Arctic rivers are included.…”

“…Still, there are few regions with concentrated in-situ gauging networks, meaning many gauged rivers do not include gauges for major tributaries or do not encompass the full discharge of a river . Future changes to the water cycle make populations vulnerable to hydro-climatic variability (Tourian et al, 2023), and necessitates a more complete record of river discharge regionally and globally.…”