Spatiotemporal variability of droughts in the Congo River Basin: The role of atmospheric moisture transport

The name ‘atmospheric river’ (AR) could easily be misinterpreted to mean rivers flowing in the sky. But, ARs actually refer to narrow bands of strong horizontal water vapour transport that are concentrated in the lower troposphere. These bands are called ‘atmospheric rivers’ because the water vapour flux they carry is close to the volume of water carried by big river systems on the ground. ARs can cause heavy rainfall events if some physical mechanisms, such as orographic enhancement, exist to set up the moisture convergence and vertical motions necessary to produce condensation. In recent decades, these significant moisture plumes have attracted increasing attention from scientific communities, especially in North America and western Europe, to further understand the connections between ARs and extreme precipitation events which can trigger severe natural disasters such as floods, mudslides and avalanches. Yet very limited research has been conducted in the Australia-Asian (A-A) region, where the important role of atmospheric moisture transport has long been recognised for its rainfall generation and variations. In this paper, we introduce a collaborative project between the Australian Bureau of Meteorology and China Meteorological Administration, which was set up to explore the detailed AR characteristics of atmospheric moisture transport embedded in the A-A monsoon system. The project in China focused on using AR analysis to explore connections between moisture transport and extreme rainfall mainly during the boreal summer monsoon season. In Australia, AR analysis was used to understand the connections between the river-like Northwest Cloud Band and rainfall in the region. Results from this project demonstrate the potential benefits of applying AR analysis to better understand the role of tropical moisture transport in rainfall generation in the extratropics, thus achieve better rainfall forecast skills at NWP (Numerical Weather Prediction), sub-seasonal and seasonal time scales. We also discuss future directions of this collaborative research, including further assessing potential changes in ARs under global warming.

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Investigating the role of the Cuvette Centrale wetlands in the hydrology, sediment and carbon fluxes of the Congo River basin

10.5194/egusphere-egu2020-10106 ◽

2020 ◽

Author(s):

Pankyes Datok ◽

Clément Fabre ◽

Sabine Sauvage ◽

Guy Moukandi ◽

Adrien Paris ◽

...

Keyword(s):

Water Resources ◽

Organic Carbon ◽

River Basin ◽

Carbon Fluxes ◽

Congo River ◽

Ecological Service ◽

The World ◽

Congo River Basin ◽

Cuvette Centrale

Keywords: Cuvette Centrale, Hydrology,&#160;Sediments, Carbon,The Congo River basin is among the largest Rivers in the world in terms of discharge and drainage area. At the heart of the basin lies the Cuvette Centrale-one of the most extensive wetlands in the world. The increasing pressure on wetland resources continues to threaten the role wetlands play in maintaining water resources and ecological service functions. Therefore, in order to understand the role of the Cuvette Centrale in water resources and ecological service functions linked to the quality of water and life in the basin, we first need to quantify its role in the hydrological, sediment and carbon dynamics. To achieve this aim, we use the Soil and Water Assessment Tool model (SWAT) &#8211; modified for tropical environments, in order to analyze the hydrology, sediment and organic carbon fluxes flowing in and flowing out of the Cuvette Centrale of the Congo River basin (CRB). The model was calibrated and validated for the 2000-2006 and 2007-2012 periods respectively by comparing the discharge and sediment output with different data sources (gauging stations and altimetry) at a daily and monthly time step. Then by adapting equations of dissolved organic carbon (DOC) and particulate organic carbon (POC) from literature, we are able to quantify the role of the Cuvette Centrale in the CRB carbon dynamics.The results reveal that the models for hydrology, sediments and carbon can represent both temporally and spatially the exports in a watershed and sheds more light on the important regulatory function of the Cuvette and the need for sustainable land use practices as well as protection of ground water resources &#160;in order to maintain wetland water quantities and quality.

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Simulated Hydrologic Response to Projected Changes in Precipitation and Temperature in the Congo River Basin

10.5194/hess-2016-152 ◽

2016 ◽

Cited By ~ 1

Author(s):

Noel Aloysius ◽

James Saiers

Keyword(s):

Water Resources ◽

River Basin ◽

Greenhouse Gas Emission ◽

Data Availability ◽

Spatiotemporal Variability ◽

Emission Scenarios ◽

Congo River ◽

Congo River Basin ◽

Projected Changes ◽

Precipitation And Temperature

Abstract. Assessing the impacts of climate change on water resources of the Congo River Basin (CRB) has attracted widespread interest; however, efforts are hindered by the lack of long-term data availability. Of particular interest to water resource planners and policy makers is the spatiotemporal variability of runoff due to the projected changes in climate. Here, with the aid of a spatially explicit hydrological model forced with precipitation and temperature projections from 25 global climate models (GCMs) under two greenhouse gas emission scenarios, we elucidate the variability in runoff in the near (2016–2035) and mid (2046–2065) 21st century compared to present. Over the equatorial, northern and southwestern CRB, models project an overall increase in precipitation and, subsequently runoff. A decrease in precipitation in the headwater regions of southeastern Congo, leads to a decline in runoff. Climate model selection plays an important role in precipitation projections, for both magnitude and direction of change. Model consensus on the magnitude and the sign (increase or decrease) of change is strong in the equatorial and northern parts of the basin, but weak in the southern basin. The multi-model approach reveals that near-term projections are not impacted by the emission scenarios. However, the mid-term projections depend on the emission scenario. The projected increase in accessible runoff (excluding flood runoff) in most parts of CRB presents new opportunities for augmenting human appropriation of water resources; at the same time, the increase in quick runoff poses new challenges. In the southeast, with the projected decrease, the challenge will be on managing the increasing demands with limited water resources.

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Dry and wet conditions in the Niger River Basin and its link with atmospheric moisture transport

10.3390/ecas2017-04150 ◽

2017 ◽

Author(s):

Rogert Sorí ◽

Raquel Nieto ◽

Anita Drumond ◽

Luis Gimeno

Keyword(s):

River Basin ◽

Moisture Transport ◽

Atmospheric Moisture ◽

Dry And Wet Conditions ◽

Niger River ◽

Atmospheric Moisture Transport

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A Lagrangian Perspective of the Hydrological Cycle in the Congo River Basin

10.5194/esd-2017-21 ◽

2017 ◽

Author(s):

Rogert Sorí ◽

Raquel Nieto ◽

Sergio M. Vicente-Serrano ◽

Anita Drumond ◽

Luis Gimeno

Keyword(s):

River Basin ◽

Hydrological Cycle ◽

Specific Humidity ◽

Lagrangian Model ◽

Air Masses ◽

Congo River ◽

Congo River Basin ◽

Highly Correlated ◽

Annual Scale

Abstract. The Lagrangian model FLEXPART was used to identify the moisture sources of the Congo River Basin (CRB) and investigate their role in the hydrological cycle. This model allows us to track atmospheric parcels while calculating changes in the specific humidity through the budget of evaporation-minus-precipitation. The method permitted the identification at an annual scale of five continental and four oceanic regions that provide moisture to the CRB from both hemispheres over the course of the year. The most important is the CRB itself, providing more than 50% of the total atmospheric moisture income to the basin. Apart from this, both the land extension to the east of the CRB together with the ocean located in the eastern equatorial South Atlantic Ocean are also very important sources, while the Red Sea source is merely important in the budget of (E − P) over the CRB, despite its high evaporation rate. The moisture sink patterns over the CRB in air masses tracked forwards from all the sources follow a latitudinal rainfall migration and are mostly highly correlated with the pattern of precipitation rate, ensuring a link between them. The analysis of the wet and dry periods in the CRB confirms the key role of the basin in modulating the fresh water balance within the basin itself.

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