Time Series Analysis of Floods across the Niger River Basin

Aich, Valentin; Koné, B.; Hattermann, Fred F.; Paton, Eva Nora

doi:10.3390/w8040165

Cited by 29 publications

(29 citation statements)

References 65 publications

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“…This has resulted in higher flood peaks, arriving earlier in the season (Mahé & Paturel, ). In recent years, the same trend is visible across the entire NRB (Aich, Koné, Hattermann, & Paton, ), and future projections suggest floods will increase even further (Aich, Liersch, et al, ). However, the regional capacity to cope with floods is much lower than for droughts.…”

Section: Introductionmentioning

confidence: 73%

Process refinements improve a hydrological model concept applied to the Niger River basin

Andersson

Arheimer

Traore

et al. 2017

Hydrological Processes

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This study examines a method to improve a process-oriented hydrological model concept applied to another region than it was first developed for. In principle, we propose to analyse and refine each major hydrological process separately, sequentially, and iteratively. To test the method, the HYPE model concept (HYdrological Predictions for the Environment, originally developed for Sweden) was here applied to the data-sparse Niger River basin in West Africa. Errors in the baseline Niger-HYPE model were analysed to identify inadequately described processes. These process descriptions were subsequently isolated and refined through a set of experiments focusing on concept development, input data enhancement, and multivariable calibration. The refinements were guided by in situ discharge observations, earth observations, local expert knowledge, and previous studies. The results show that the original model concept could simulate the annual cycle of discharge, but not the magnitudes or daily dynamics (56-station average Nash-Sutcliffe Efficiency = −1). The main processes requiring improved descriptions were precipitation, evaporation, surface runoff, infiltration, soil storage, reservoir regulations, aquifer recharge, and flooding and river-atmosphere exchange in the Inner Niger Delta. Of these, evaporation, flooding and river-atmosphere exchange differ so much between Sweden and the Niger River that the model concept had to be refined. All refinements were synthesized in a new model version (Niger-HYPE2.0) performing significantly better across the basin (56-station average Nash-Sutcliffe Efficiency = 0.4). This study demonstrates the danger of applying a model off the shelf, and the obligation to carefully evaluate and revise process descriptions when applying a model concept to a new region. Moreover, the results indicate that our approach to separately, sequentially, and iteratively refine processes together with local experts can substantially improve process-oriented hydrological models. Hydrological models can be useful tools for operational water management and strategic planning to handle societal challenges such as floods, droughts, energy supply, infrastructure design, food production, ecosystem function, sanitation, and drinking water use. However, to be useful, they must represent the dominant hydrological processes (HP) of the region in which they are applied in order to simulate the ever-changing hydrological dynamics (Montanari et al., 2013). In other words, a model should not only reproduce the hydrological regimes, but also provide "the right answers for the right reasons" (Kirchner, 2006). Commonly, a single hydrological model concept (i.e., structure, equations, and code) is applied to various regions differing strongly in dominant HP, under the assumption of being -------------------------------------------------------------------------This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, pr...

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Section: Introductionmentioning

confidence: 73%

Process refinements improve a hydrological model concept applied to the Niger River basin

Andersson

Arheimer

Traore

et al. 2017

Hydrological Processes

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“…In Africa, flood related fatalities and associated economic losses have increased considerably over the past half century, and this trend, which is also related to urbanization dynamics, is expected to have direct consequences on the population [37]. This increase in flood related fatalities and economic losses may be due to an increase in inundations, but also potentially to an increase in exposure and vulnerability, as suggested by Aich et al (2016) [38]. The results of Paeth et al [39] and Lafore et al [40] also suggest that many factors, from synoptic-scale to large-scale circulations, including regional features and teleconnection patterns, contribute to the extremeness of the rainfall events that lead to flooding.…”

Section: Principal Component Analysis (Pca)mentioning

confidence: 98%

“…However, recent studies have reached more mitigated conclusions. Among others, Aich et al [38] argued that LULCC and climatic changes could contribute to different degrees in the different basins.…”

Section: Land Use/land Cover Changes and Their Hydrological Consequencesmentioning

confidence: 99%

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Evolution of Surface Hydrology in the Sahelo-Sudanian Strip: An Updated Review

Descroix

Guichard

Grippa

et al. 2018

Water

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Abstract:In the West African Sahel, two paradoxical hydrological behaviors have occurred during the last five decades. The first paradox was observed during the 1968-1990s 'Great Drought' period, during which runoff significantly increased. The second paradox appeared during the subsequent period of rainfall recovery (i.e., since the 1990s), during which the runoff coefficient continued to increase despite the general re-greening of the Sahel. This paper reviews and synthesizes the literature on the drivers of these paradoxical behaviors, focusing on recent works in the West African Sahelo/Sudanian strip, and upscaling the hydrological processes through an analysis of recent data from two representative areas of this region. This paper helps better determine the respective roles played by Land Use/Land Cover Changes (LULCC), the evolution of rainfall intensity and the occurrence of extreme rainfall events in these hydrological paradoxes. Both the literature review and recent data converge in indicating that the first Sahelian hydrological paradox was mostly driven by LULCC, while the second paradox has been caused by both LULCC and climate evolution, mainly the recent increase in rainfall intensity.

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“…In addition to the natural systems, societal infrastructure is also becoming more sensitive to weather and climate extremes, exacerbated by climate variability and land-vulnerability [3][4][5][6]. As a result, peri-urban catchments, made of a mixture of natural or agricultural lands and urbanized areas, are always more frequently affected by the broad spectrum of multiple damaging hydrological events (MDHEs) [7], as a simultaneously triggering of different types of phenomena, such as landslides and floods.…”

Section: Introductionmentioning

confidence: 99%

Historical Storminess and Hydro-Geological Hazard Temporal Evolution in the Solofrana River Basin—Southern Italy

Longobardi

Diodato²,

Mobilia

2016

Water

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Precipitation extremes have always been part of the Earth's climate system and associated multiple damaging hydrological events (MDHEs), the simultaneous triggering of different types of phenomena (landslides and floods), affect an always-increasing portion of human settlement areas. This paper aims to investigate the relationship between the temporal evolution of severe geomorphological events and combined precipitation indices as a tool to improve understanding the hydro-geological hazard at the catchment scale. The case study is the Solofrana river basin, Southern Italy, and the focus is on four of main municipalities severely affected by natural disasters. Data for about 45 MDH events, spanning 1951-2014, have been collected and analyzed for this purpose. A preliminary monthly scale analysis of event occurrences highlights a pronounced seasonal characterization of the phenomenon, as about 60% of the total number of reported events take place during the period from September to November. Following, a statistical analysis clearly indicates a significant increase in the frequency of occurrences of MDHEs during the last decades.Such an increase appears to be related to non-stationary features of an average catchment scale rainfall-runoff erosivity index, which combines maximum monthly, maximum daily, and a proxy of maximum hourly precipitation data.

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Time Series Analysis of Floods across the Niger River Basin

Cited by 29 publications

References 65 publications

Process refinements improve a hydrological model concept applied to the Niger River basin

Process refinements improve a hydrological model concept applied to the Niger River basin

Evolution of Surface Hydrology in the Sahelo-Sudanian Strip: An Updated Review

Historical Storminess and Hydro-Geological Hazard Temporal Evolution in the Solofrana River Basin—Southern Italy

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