The impact of drought on agricultural area in Burkina Faso and assessment of future cropping potential using a combination of EO and climate data.

Climate change is one of the biggest challenges for agriculture in West Africa. Traditional agriculture, based on the rainy season, is threatened by rising temperatures and increasingly variable occurrence of precipitation. Due to climate change the normally regular occurrence of the rainy season is shifting, the growing season is becoming shorter and is increasingly interrupted by dry spells during the rainy season. Crop losses and crop failures are the consequences. EO has the potential to identify and quantify the impact of precipitation anomalies on agriculture area and identify spatial and temporal patterns of area affected by precipitation deficits. From these patterns, trends can be derived and a future agricultural use can be evaluated. In addition, vulnerable areas can be identified and adaptation measures can be taken in order to secure future harvest. In this study agricultural productivity and the impact of precipitation anomalies are investigated by a combination of EO and climate data in Burkina Faso. Therefore LAI (Leaf Area Index) data are derived from multi-temporal Sentinel-2 data and phenological time series are evaluated regarding the effects of precipitation deficits. Crop failure can be caused not only by drought but also by heavy precipitation events, erosion, pests or mismanagement. Therefore, additional climate data regarding the occurrence of drought events will be analyzed in order to clearly attribute the possible decline in productivity to a precipitation deficit. Not only the length of drought events is considered, but also their severity. For this purpose, the Standardized Precipitation Evapotranspiration Index (SPEI) is calculated, which includes not only precipitation data and temperature but also evapotranspiration. SPEI is calculated for the period 1979 to present using ERA5 data and in addition 2 CORDEX climate scenarios (RCP 4.5 and RCP 8.5) are evaluated in terms of drought events until 2050. The results show that drought events are increasing in both length and severity - countrywide. Evaluations of the Sentinel-2 derived LAI on agricultural area show that crop productivity is significantly decreasing within areas affected by drought events. Based on these results, recommendations for policy makers and NGOs can be formulated to initiate early adaptation measures in the affected area to minimize future crop losses due to precipitation deficits. The study shows that the combination of EO data and climate data can be used successfully to identify agricultural areas affected by drought events and provide a potential assessment for future agriculture activities