Modélisation de l’impact du changement climatique sur le blé en zone semi-aride

Abstract

This study was conducted in a semi-arid region of Setif province over three consecutive cropping seasons (2021-2024) to investigate adaptation strategies for the production of durum and soft wheat under the challenges of climate change. Climate forecasts for the short-term (2030) and medium-term (2050), across all SSP scenarios, predict an increase in average temperature (reaching 17.89°C and 18.63°C in 2030 and 2050 respectively) and a decrease in annual rainfall amounts (down to 288.824 mm, 270.758 mm, and 260.244 mm for the corresponding periods). The Aquacrop model was employed to simulate yield, biomass, soil moisture, and vegetation cover for two wheat species durum wheat (Oued el Bared) and soft wheat (El Wifaq) under three SSP scenarios for the future horizons (2020-2039) and (2040-2059). Model accuracy was evaluated using statistical indicators (NRMSE, RMSE, D ,r), with values for durum wheat yield as follows: d=0.92, rmse=0.34, nrmse=22.1;r=0.99, and for soft wheat: d=0.83, rmse=0.61, nrmse=34.7,r=0.94 confirming strong reliability of the simulations. Compared to the reference period (1995-2014) where average yields were 6 q/ha for durum wheat and 7.4 q/ha for soft wheat, future projections show marked increases: durum wheat yields range from 14.20 to 16.60 q/ha (2020-2039) and 15.20 to 28.75 q/ha (2040-2059); soft wheat yields range from 9.5 to 14 q/ha (2020-2039) and 10.5 to 15.5 q/ha (2040-2059), depending on the scenario. Durum wheat dry biomass increases from 13.17 q/ha (reference) to 31.52–36.83 q/ha (2020-2039) and 33.73–39.38 q/ha (2040-2059); soft wheat dry biomass rises from 14 q/ha to 18–28 q/ha and 20–28.86 q/ha for the same periods. Water productivity also improves from 0.15 kg/m³ (reference) to 0.39–0.46 kg/m³ for durum wheat and 0.16–0.18 kg/m³ for soft wheat over 2020-2039; and for 2040-2059, it reaches 0.41–0.84 kg/m³ (durum) and 0.22–0.53 kg/m³ (soft). These findings indicate that increased atmospheric CO₂ enhances photosynthesis, reduced evaporation and early sowing supported by decreased precipitation favor yield and water use efficiency, although growing periods are shortened by rising temperatures. Thus, these strategies offer promising avenues for sustaining agricultural production in semi-arid regions under climate change.