Simulated hydrologic response to projected changes in precipitation and temperature in the Congo River basin

Aloysius, Noel; Saiers, James E.

doi:10.5194/hess-21-4115-2017

Cited by 36 publications

(16 citation statements)

References 63 publications

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“…With regard to data, and given a critical lack of in-situ data, there have been efforts made towards the use of global datasets, including global climate (both reanalysis and satellite-based) and physical basin properties datasets as well as satellite altimetry for prediction of water level and discharge. With regard to process understanding, a number of functions have been developed to improve existing model structures, most specifically to address the issues of modeling natural storages of wetlands and lakes that dominate the hydrology of the Congo Basin as well as the routing functions of the large river channels [112][113][114][115]. However, there have also been a number of problems that challenged the various modeling exercises.…”

Section: Hydrological Modeling In the Congo River Basinmentioning

confidence: 99%

Recent Budget of Hydroclimatology and Hydrosedimentology of the Congo River in Central Africa

Laraque¹,

N’kaya

Orange

et al. 2020

Water

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Although the Congo Basin is still one of the least studied river basins in the world, this paper attempts to provide a multidisciplinary but non-exhaustive synthesis on the general hydrology of the Congo River by highlighting some points of interest and some particular results obtained over a century of surveys and scientific studies. The Congo River is especially marked by its hydrological regularity only interrupted by the wet decade of 1960, which is its major anomaly over nearly 120 years of daily observations. Its interannual flow is 40,500 m3 s−1. This great flow regularity should not hide important spatial variations. As an example, we can cite the Ubangi basin, which is the most northern and the most affected by a reduction in flow, which has been a cause for concern since 1970 and constitutes a serious hindrance for river navigation. With regard to material fluxes, nearly 88 × 106 tonnes of material are exported annually from the Congo Basin to the Atlantic Ocean, composed of 33.6 × 106 tonnes of TSS, 38.1 × 106 tonnes of TDS and 16.2 × 106 tonnes of DOC. In this ancient flat basin, the absence of mountains chains and the extent of its coverage by dense rainforest explains that chemical weathering (10.6 t km−2 year−1 of TDS) slightly predominates physical erosion (9.3 t km−2 year−1 of TSS), followed by organic production (4.5 t km−2 year−1 of DOC). As the interannual mean discharges are similar, it can be assumed that these interannual averages of material fluxes, calculated over the longest period (2006–2017) of monthly monitoring of its sedimentology and bio-physical-chemistry, are therefore representative of the flow record available since 1902 (with the exception of the wet decade of 1960). Spatial heterogeneity within the Congo Basin has made it possible to establish an original hydrological classification of right bank tributaries, which takes into account vegetation cover and lithology to explain their hydrological regimes. Those of the Batéké plateau present a hydroclimatic paradox with hydrological regimes that are among the most stable on the planet, but also with some of the most pristine waters as a result of the intense drainage of an immense sandy-sandstone aquifer. This aquifer contributes to the regularity of the Congo River flows, as does the buffer role of the mysterious “Cuvette Centrale”. As the study of this last one sector can only be done indirectly, this paper presents its first hydrological regime calculated by inter-gauging station water balance. Without neglecting the indispensable in situ work, the contributions of remote sensing and numerical modelling should be increasingly used to try to circumvent the dramatic lack of field data that persists in this basin.

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Section: Hydrological Modeling In the Congo River Basinmentioning

confidence: 99%

Recent Budget of Hydroclimatology and Hydrosedimentology of the Congo River in Central Africa

Laraque¹,

N’kaya

Orange

et al. 2020

Water

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“…In addition, visual inspection through scatter plots revealed good agreement between the observed and the PGF temperature, and thus, the suitability of the PGF temperature data for the analysis of thermal bioclimatic trends in Iran. The PGF data has also been found suitable for trend analysis in a number of studies at global [49,50] and regional [7,32,51,52] scales, including in Asia [7,37,[53][54][55].…”

Section: Princeton Global Meteorological Forcing Datamentioning

confidence: 99%

Spatial Pattern of the Unidirectional Trends in Thermal Bioclimatic Indicators in Iran

et al. 2019

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Changes in bioclimatic indicators can provide valuable information on how global warming induced climate change can affect humans, ecology and the environment. Trends in thermal bioclimatic indicators over the diverse climate of Iran were assessed in this study to comprehend their spatio-temporal changes in different climates. The gridded temperature data of Princeton Global Meteorological Forcing with a spatial resolution of 0.25° and temporal extent of 1948–2010 was used for this purpose. Autocorrelation and wavelets analyses were conducted to assess the presence of self-similarity and cycles in the data series. The modified version of the Mann–Kendall (MMK) test was employed to estimate unidirectional trends in 11 thermal bioclimatic indicators through removing the influence of natural cycles on trend significance. A large decrease in the number of grid points showing significant trends was noticed for the MMK in respect to the classical Mann–Kendall (MK) test which indicates that the natural variability of the climate should be taken into consideration in bioclimatic trend analyses in Iran. The unidirectional trends obtained using the MMK test revealed changes in almost all of the bioclimatic indicators in different parts of Iran, which indicates rising temperature have significantly affected the bioclimate of the country. The semi-dry region along the Persian Gulf in the south and mountainous region in the northeast were found to be more affected in terms of the changes in a number of bioclimatic indicators.

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“…However, while bias correction of atmospheric variables was recognized a necessary step for offline impact and adaptation studies especially via hydrological models (Aloysius & Saiers, 2017;Teutschbein & Seibert, 2012), it is not easy to bias-correct GCM/ESM runoff outputs to be then converted into river discharge. To date, lack of spatially explicit data on overland runoff generation prevents any point-by-point evaluation and bias correction of this variable (Zaitchik et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

“…The reproduction of the hydrological cycle for large rivers (i.e., approximately those with a drainage area above 100,000 km 2 according to Liebscher, 1993) was recently evaluated starting from the runoff generated by GCMs/ESMs at each grid point and deriving discharge values following unrouted (Alkama et al, 2013;Bring et al, 2015) or routed (Koirala et al, 2014) approaches or through offline forcing of GHMs, DGVMs/LSMs, and mesoscale hydrological models by CMIP5 climate simulations (Aloysius & Saiers, 2017;Bring et al, 2017;Yu et al, 2016). Moreover, to our knowledge, evaluations on how CMIP5 models simulate online the river discharge, at least at the land-sea interface, are still missing (Flato et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Freshwater Flow From Rivers to the Sea in CMIP5 Simulations: Insights From the Congo River Basin

Santini

Caporaso

2018

JGR Atmospheres

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Despite the multisectoral importance of water resources in the context of climate change, it remains still difficult to correctly simulate the terrestrial water cycle via general circulation and Earth system models. While existing model evaluation efforts from the Climate Model Intercomparison Project 5 (CMIP5) are mainly focused on atmospheric variables, we considered here the simulated freshwater flux into the ocean for the river Congo by 20 CMIP5 models. We found that many advancements are still required in global modeling to satisfactorily reproduce the discharge, at least for Congo River. Only the distribution of intermonthly and interannual anomalies of simulated flow, calculated as percent deviations from the respective long‐term average, appears not significantly different from that found in observations. Conversely, most of the models appear to largely overestimate the streamflow seasonal cycle, up to 4–5 times for some months. Further, when looking at severer anomalies in terms of abnormal low‐flow periods (hydrological droughts), the models seem to underestimate their frequency and magnitude while overestimating the duration of deficit conditions with respect to hypothetical water demand. These overall discrepancies between models and observations could propagate in reproducing the land‐ocean feedbacks, as discharge is known to affect sea surface salinity and temperature and, thus, the regional to global ocean circulation and climate. Moreover, biased model‐based discharge simulations could wrongly support water management and infrastructure planning for large river basins, especially when using models instead of measurements, as in case of ungauged rivers, or however when clarification of models' uncertainty is missed.

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Simulated hydrologic response to projected changes in precipitation and temperature in the Congo River basin

Cited by 36 publications

References 63 publications

Recent Budget of Hydroclimatology and Hydrosedimentology of the Congo River in Central Africa

Recent Budget of Hydroclimatology and Hydrosedimentology of the Congo River in Central Africa

Spatial Pattern of the Unidirectional Trends in Thermal Bioclimatic Indicators in Iran

Evaluation of Freshwater Flow From Rivers to the Sea in CMIP5 Simulations: Insights From the Congo River Basin

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