A dynamic land use/land cover input helps in picturing the Sahelian paradox: Assessing variability and attribution of changes in surface runoff in a Sahelian watershed

Yonaba, Roland; Biaou, Angelbert; Koïta, Mahamadou; Fowé, Tazen; Mounirou, Lawani Adjadi; Zouré, Cheick Oumar; Queloz, Pierre; Karambiri, Harouna; Yacouba, Hamma

doi:10.1016/j.scitotenv.2020.143792

Cited by 84 publications

(45 citation statements)

References 92 publications

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“…Moreover, further research is needed to understand at river basin scale the behaviour of underlying factors of hydrological changes during the last period. For this purpose, recent methodologies developed at small sub-basin or plot level [70,71] could be successfully integrated with large-scale remote sensing and spatial analysis approaches [23].…”

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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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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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“…In addition, LUCC such as reservoir construction, irrigation abstraction, and soil and water conservation projects have a growing impact on the regional hydrological cycle (Iqbal et al, 2018;Xu et al, 2019;Yang et al, 2019;Zhao et al, 2021), especially under the influence of urbanization due to rapid socioeconomic development. Different land use types have different effects on precipitation interception, blocking, transpiration, and infiltration (Berg et al, 2016;Yonaba et al, 2021), so LUCC not only causes changes in surface or groundwater volume, but also changes the way regional water circulates. The expansion of urban land will reduce water retention and infiltration, increase the SF, and even increase the flood frequency (Baker and Miller, 2013;Wang Q et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, several studies have directly attributed LUCC to human activities (Ahn and Merwade, 2014;Zhai and Tao, 2017;Xu et al, 2020), which needs to be adequately discussed. In addition, the impacts of climate change and LUCC on regional hydrological processes are spatially distinct Yonaba et al, 2021). Understanding these impacts requires an accurate assessment of the different conditions for a given region.…”

Section: Introductionmentioning

confidence: 99%

Impacts of Climate Change and Land Use/Cover Change on Regional Hydrological Processes: Case of the Guangdong-Hong Kong-Macao Greater Bay Area

Tan

Liu

Tian

et al. 2022

Front. Environ. Sci.

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Climate change and land use/cover change (LUCC) have been widely recognized as the main driving forces that can affect regional hydrological processes, and quantitative assessment of their impacts is of great importance for the sustainable development of regional ecosystems, land use planning and water resources management. This study investigates the impacts of climate change and LUCC on variables such as streamflow (SF), soil moisture (SM) and evapotranspiration (ET) in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) by using Soil and Water Assessment Tools (SWAT) model under different scenarios during 1979–2018. The results show that the simulation performances were overall good, with Nash-Sutcliffe Efficiency Coefficient (NSE) and coefficient of determination (R2) greater than 0.80 for the monthly-scale SF calibration and validation. According to the results of trend and change point tests of meteorological series, the baseline period (1979–1997) and the interference period (1998–2018) were determined. Interestingly, other land use types were basically converted to urban land, leading to a rapid urbanization in the GBA. Compared with the SF values of the eight estuaries of the Pearl River Basin in the baseline period, both climate change and LUCC has led to the decrease in the SF values in the interference period, and the combined effect of climate change and LUCC was slightly greater than their individual effect. Overall, climate change and LUCC both have important impacts on regional hydrological processes in the GBA.

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“…The formation of overland and subsurface runoff significantly affects the dynamics of floods. In Poland and other countries, this problem mainly concerns sealed surfaces, i.e., urbanized areas [11,[39][40][41][42][43], as well as mountain areas [44][45][46][47]. The sealing of the area causes an increase in the number of floods with a rapid course of a flood wave, but of short duration.…”

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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A dynamic land use/land cover input helps in picturing the Sahelian paradox: Assessing variability and attribution of changes in surface runoff in a Sahelian watershed

Cited by 84 publications

References 92 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)

Impacts of Climate Change and Land Use/Cover Change on Regional Hydrological Processes: Case of the Guangdong-Hong Kong-Macao Greater Bay Area

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

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