Multi-scale analysis of runoff from a statistical perspective in a small Sahelian catchment under semi-arid climate

Mounirou, Lawani Adjadi; Zouré, Cheick Oumar; Yonaba, Roland; Paturel, Jean‐Emmanuel; Mahé, Gil; Niang, Dial; Yacouba, Hamma; Karambiri, Harouna

doi:10.1007/s12517-020-5141-2

Cited by 19 publications

(16 citation statements)

References 79 publications

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“…Therefore, the RC is still growing but the observed dynamics in the other tributaries could suggest that an inflection point could be reached next decades with the end of the Sahelian paradoxes. The time lag in reaching the inflection point of RCs rise could be related to the latitudinal gradient, the level of anthropisation and therefore LULC changes and also to the extension of the basins because of the scale effect [64].…”

Section: A New Hydrological Era?mentioning

confidence: 99%

Recent Changes in Hydroclimatic Patterns over Medium Niger River Basins at the Origin of the 2020 Flood in Niamey (Niger)

Massazza¹,

Bacci²,

Descroix³

et al. 2021

Water

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Niamey, the capital of Niger, is particularly prone to floods, since it is on the banks of the Niger River, which in its middle basin has two flood peaks: one in summer (the red flood) and one in winter (the black flood). In 2020, the Niger River in Niamey reached its all-time highest levels following an abundant rainy season. On the other hand, the floods in Niamey have been particularly frequent in the last decade, a symptom of a change in hydroclimatic behaviour already observed since the end of the great droughts of the 1970s and 1980s and which is identified with the name of Sahelian Paradox. This study, starting from the analysis of the 2020 flood and from the update of the rating curve of the Niamey hydrometric station, analyses the rainfall–runoff relationship on the Sahelian basins of the Medium Niger River Basin (MNRB) that are at the origin of the local flood. The comparative analysis of runoffs, annual maximum flows (AMAX) and runoff coefficients with various rainfall indices calculated on gridded datasets allowed to hydroclimatically characterise the last decade as a different period from the wet one before the drought, the dry one and the post-drought one. Compared to the last one, the current period is characterised by a sustained increase in hydrological indicators (AMAX +27%) consistent with the increase in both the accumulation of precipitation (+11%) and the number (+51%) and magnitude (+54%) of extreme events in the MNRB. Furthermore, a greater concentration of rainfall and extremes (+78%) in August contributes to reinforcing the red flood’s positive anomalies (+2.23 st.dev in 2020). The study indicates that under these conditions the frequency of extreme hydrological events in Niamey will tend to increase further also because of the concurrence of drivers such as river-bed silting and levee effects. Consequently, the study concludes with the need for a comprehensive flood-risk assessment on the Niamey city that considers both recent hydroclimatic trends and urbanisation dynamics in flood zones hence defining the most appropriate risk-reduction strategies.

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Section: A New Hydrological Era?mentioning

confidence: 99%

Recent Changes in Hydroclimatic Patterns over Medium Niger River Basins at the Origin of the 2020 Flood in Niamey (Niger)

Massazza¹,

Bacci²,

Descroix³

et al. 2021

Water

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“…(1) the large increase in rainfall conditions; (2) the almost exclusive sensitivity of surface runoff to rainfall conditions; (3) the scale of observation which is, in this study, relatively small (37 km 2 ). As shown in Mounirou et al [2020Mounirou et al [ , 2021, surface runoff generating processes change with scale. Likewise, Gbohoui et al [2021] showed that for varying nested watersheds scale, the control of environmental conditions (i.e., land use) is dependent on the size of the watershed.…”

Section: On the Contributions Of Climate And Land Use Changes To Surf...mentioning

confidence: 99%

“…The complexity of processes in the water cycle in Sahelian watersheds remains a major challenge to hydrologists to date, for various reasons: first, rainfall conditions in this context are specifically defined by high intensities rainfall of short durations [Biasutti, 2019], which quickly onsets a highly nonlinear Hortonian surface runoff response [Mounirou et al, 2020]. Second, surface runoff generation mechanisms are typically dependent on both antecedent rainfall but also soil surface conditions, the latter being prone to surface crusting and sealing; which, in turn, affects other key processes such as infiltration, and evaporation [Valentin, 2018.…”

Section: Introductionmentioning

confidence: 99%

Future climate or land use? Attribution of changes in surface runoff in a typical Sahelian landscape

Yonaba¹,

Mounirou²,

Fowé³

et al. 2024

Comptes Rendus. Géoscience

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“…Similar conditions may also apply to bare soil. Measurements on bare soil [31,32] indicate that overland runoff on this kind of surface is higher than that on cultivated land or soil with vegetation cover. The research carried out by Mounirou et al [43] showed the effect of land use and land cover changes on the water cycle in a small Sahelian watershed.…”

Section: Msme Model (Verification Of Suitability For the Total Runoff...mentioning

confidence: 99%

“…The most reliable results of surface and subsurface runoff studies are provided by field and laboratory measurements. In most cases, research on experimental plots focuses on determining the impact of plot use or dimensions on the runoff [28][29][30][31][32][33], but the infiltration process is rarely monitored on them [34][35][36]. On the other hand, the best way to select soil conditions, control the intensity of rainfall, or choose the instrumentation of the measuring model is based on laboratory measurements.…”

Section: Introductionmentioning

confidence: 99%

Influence of Rainfall Events and Surface Inclination on Overland and Subsurface Runoff Formation on Low-Permeable Soil

et al. 2022

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This paper presents the results of laboratory tests that allowed us to determine the effect of the soil surface inclination and its initial moisture content on the formation of overland and subsurface runoff. The experiments were carried out for the soil that is commonly present in the southern part of Poland, including the Outer Carpathians. The results of these measurements served as a reference for overland runoff calculations using the Richards model, simplified Green–Ampt model, and the empirical model (MSME). The results of the measurements showed that, for low-permeable soil, overland runoff is the dominant form. It was shown that a slope in the range of 2.5–5.0% does not have a significant effect on the amount of overland runoff, but affects its dynamics. The measurements also showed that the starting time and amount of overland runoff are strictly associated with the initial soil moisture content. High soil moisture content in the period preceding the onset of rainfall causes faster generation and an increase in overland runoff, which is caused by the saturation of the surface layer of the soil. This mechanism was confirmed by the results of calculations using the Richards model and measurements of the electrical resistance of the soil. Theoretical calculations showed that the results of the runoff calculations using the Richards and Green–Ampt models are strongly dependent on the hydraulic properties of the soil adopted for the analysis. It was also demonstrated that the modified MSME model satisfactorily estimates the amount of overland and subsurface runoff, but requires parameter calibration based on existing hydrological data.

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Multi-scale analysis of runoff from a statistical perspective in a small Sahelian catchment under semi-arid climate

Cited by 19 publications

References 79 publications

Recent Changes in Hydroclimatic Patterns over Medium Niger River Basins at the Origin of the 2020 Flood in Niamey (Niger)

Recent Changes in Hydroclimatic Patterns over Medium Niger River Basins at the Origin of the 2020 Flood in Niamey (Niger)

Future climate or land use? Attribution of changes in surface runoff in a typical Sahelian landscape

Influence of Rainfall Events and Surface Inclination on Overland and Subsurface Runoff Formation on Low-Permeable Soil

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