Kamali Bahareh, Abbaspour Karim , Lehmann Anthony, Wehrli Bernhard, Yang Hong (2017), Uncertainty-based auto-calibration for crop yield – the EPIC+ procedure for a case study in Sub-Saharan Africa, in European Journal of Agronomy
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Stefanovic Julia, Yang Hong, Zhou Yuan, Kamali Bahareh, Ogalleh Sarah, Adaption to climate change: a case study of two agricultural systems from Kenya, in Climate and Development
Kamali Bahareh, Abbaspour Karim, Lehmann Anthony, Wehrli Bernhard, Yang Hong, Spatial assessment of maize physical drought vulnerability in Sub-Saharan Africa: Linking drought exposure with crop failure, in Global and Planetary Change
Droughts can have devastating effects on water supply, crop production, food security and many other aspects of human livelihood. The impact is particularly severe in Sub-Saharan Africa (SSA) where rainfed subsistence farming dominates the food production and where political, social and economic systems are often inadequately prepared to cope with disasters. The recurrence of droughts in the past decades has triggered many famines in the sub-continent. The severity of droughts and their impacts is projected to increase as a consequence of climate change. There is a large literature on assessing impact of droughts on food production and vulnerability of a society to droughts. Studies investigating drought impact on crop production in a historical context have typically been conducted by establishing a drought index and correlating it with recorded crop yield or food production in the observed areas. Regression models have been commonly applied for the investigation, where drought effects are presented as a percentage of yields or production variance that could be explained by the model used. Application of process-based bio-physical crop models (crop models hereafter) to specifically quantify the drought effects on crop yield has been very limited in retrospective studies. Large geographical scale crop modeling in assessing drought impact in SSA has, to the best of our knowledge, not been applied. Two shortcomings exist in the drought index-based crop impact assessment. One concern is that the approach cannot specify the types of droughts and most critical times of their impacts on crop yields. In reality, the timing of the occurrence of drought with respect to developmental stages of individual crops is crucial to determining the yield. Another shortcoming is that most such assessments do not distinguish the ‘loss of crop yield’ and ‘failure of production’. In reality, the scopes of the two can be very different. Generally speaking, drought-induced yield loss is more directly related to water stress during crop growth, whereas production reduction in a drought event has multiple drivers, apart from yield loss. This is particularly so in many SSA countries where a relatively small drought often leads to a large reduction in crop production. Concerning the future climate change, it can be expected that the magnitude of the drought impact on crop production will far exceed what is projected based on crop yield loss alone. This gap would especially be large in the regions that are more vulnerable to drought. Motivation of the proposed project is to address the above specified gaps in the assessment of drought impact on crops. Here we propose to apply a process-based biophysical crop model to quantify the impact of droughts on crop yields and food production in a historical context. The study offers the opportunity to perform a large geographical scale crop modeling with high spatial resolution over the whole of SSA. Three specific objectives of the proposed project include: 1) Applying the GIS based crop model (GEPIC) to simulate the impact of historic droughts on crop yields with specification of duration and types of droughts concerning different stages of crop growth; 2) Assessing the crop-drought vulnerability by incorporating the yield loss (simulated), the relative production failure (statistics), as well as the frequency of drought events (identified); 3) Investigating the socio-economic factors influencing the crop-drought vulnerability and mapping out the hot spots of high vulnerability to droughts in SSA. The proposed project endeavors to advance the applicability of crop models for assessing drought impacts on crop yields and crop-drought vulnerability, while pinpointing the limitations that remain. By providing an integrated bio-physical and socio-economic assessment, the study helps identify entry points for developing effective measures to improve the drought coping capacity in SSA. Last but not least, the knowledge learnt from the historical context helps enhance the projection of impact of future extreme dry weather conditions on crop yield and food production and facilitate the societal preparedness to drought impact.