Abstract
Abstract The Niger basin has experienced historical drought episodes and floods in recent times. Reliable hydrological modelling has been hampered by missing values in daily river discharge data. We assessed the potential of using the Multivariate Imputation by Chained Equations (MICE) to estimate both continuous and discontinuous daily missing data across different spatial scales in the Niger basin. The study was conducted on 22 discharge stations that have missing data ranging from 2% to 70%. Four efficiency metrics were used to determine the effectiveness of MICE. The flow duration curves (FDC) of observed and filled data were compared to determine how MICE captured the discharge patterns. Mann-Kendall, Modified Mann-Kendall, Pettit and Sen's Slope were used to assess the complete discharge trends using the gap-filled data. Results shows that MICE near perfectly filled the missing discharge data with Nash-Sutcliffe Efficiency (NSE) range of 0.94–0.99 for the calibration (1992–1994) period. Good fits were obtained between FDC of observed and gap-filled data in all considered stations. All the catchments showed significantly increasing discharge trend since 1990s after gap filling. Consequently, the use of MICE in handling missing data challenges across spatial scales in the Niger basin was proposed.
Highlights
West Africa have been ascribed with adverse climate change impacts
The Multivariate Imputation by Chained Equations (MICE) gap filling method was evaluated at three discharge stations (Koulikoro, KeMacina and Dire), which had less than 5% missing data (Figure 3)
We evaluated the performance of MICE in all 22 catchments by comparing flow duration curves (FDC) of inputted data with the FDC
Summary
West Africa have been ascribed with adverse climate change impacts. The region experienced decline in food security due to warming, changing precipitation patterns, and greater frequency of some extreme events (IPCC 2019). Climate change has driven decreased discharge and increased drought in the Sahel since. High intensity rainfall and flood magnitudes were projected to increase in coming decades (Sylla et al 2015; Aich et al 2016). An increasing trend for annual rainfall-runoff erosivity and soil loss is expected in the 21st century (Amanambu et al 2019). Sylla et al (2018) disclosed that increase in temperature will lead to decrease in the potential to sustain large dams and irrigated agriculture in West Africa Water resources are fundamental for several sectors such as hydropower, crop production and fisheries (Roudier et al 2014). Sylla et al (2018) disclosed that increase in temperature will lead to decrease in the potential to sustain large dams and irrigated agriculture in West Africa
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