Climate Variability and Groundwater Response: A Case Study in Burkina Faso (West Africa)

Abstract

West Africa experiences great climate variability, as shown by the long-lasting drought since the 1970s. The impacts of the drought on surface water resources are well documented but remain less studied regarding groundwater resources. The nexus between climate variability and groundwater level fluctuations is poorly documented in this area. The present study focuses on the large reserve of groundwater held by the Kou catchment, a tributary of Mouhoun river (formerly the Black Volta) in the southwest of Burkina Faso, in the Sudanian region. Analyses were undertaken using climatic time series , two rivers' hydrometric data , and 21 piezometers' time series (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014) applying statistical trend (Mann-Kendall) and break (Pettitt) tests, correlation analysis, and principal component analysis. The analyses showed that rainfall in the area underwent a significant break in 1970 with an 11%-16% deficit between the period before the break and the period after the break that resulted in a deficit three times greater for both surface and base flows. This significant deficit in flow results from the combined effect of a decrease in rainfall and an increase in evapotranspiration. The response of the catchment to the slight increase in rainfall after 1990 was highly dependent on hydrological processes. At Samendéni, on the Mouhoun River, the flow increased with a slight delay as compared to rainfall, because of the slow response of the base flow. Whereas at Nasso on the Kou river, the flow steadily decreased. The analysis showed that the groundwater level responds to rainfall with a delay. Its response time to seasonal fluctuations ranges from 1 to 4 months and its response time to interannual variations exceeds the timescale of one year. This response is highly dependent on the local aquifer's physical characteristics, which could explain the spatial heterogeneity of the groundwater response.

Climate analysis for agricultural improvement of the Economic Community of West African States according to Kppen and Thornthwaite

“…Also, the West African countries have been experiencing huge climate variability in the last decades with direct impact in the groundwater (Tirogo et al, 2016), although it has been shown a resilience for shortterm inter-annual variation (Lapworth et al, 2013). Climate variability has also been verified by differences on tree-rings along countries such as Ivory Coast (de Ridder et al, 2013).…”

Chronic groundwater decline: A multi-decadal analysis of groundwater trends under extreme climate cycles

“…Abdullahi et al (2015) identified both significant positive and negative trends for the north-eastern region of Peninsula Malaysia for different time periods, suggesting overall trends across an entire sampling period may mask significant trends within distinct climatic phases. Similarly, Tirogo et al (2016) found different significant MK groundwater trends in multi-year climatic phases in West Africa. These studies suggest that an approach that includes overall trend analysis and trend analysis within distinct climatic phases may provide more insightful information about potentially stressed groundwater systems.…”

Análise de sensibilidade e calibração espacial do modelo SWAT aplicado em uma bacia do litoral pernambucano através de dados climáticos observados e de reanálise (Analysis of sensitivity and calibration of the SWAT model applied in a basin in northeast of Brazil using observed and reanalysis climatic data)

“…For subbasin 5, the driest subbasin, the value of of GW_DELAY was increased by 53.05 days. In addition, other hydrogeological conditions also contribute to the flow of groundwater, such as transmissivity and storage coefficient indicated in the work of Tirogo et al (2016) in Burkina Faso in West Africa.…”