Abstract/Summary

South-East Kazakhstan (SEK) is an important agricultural region which strongly depends on irrigation using meltwater from the mountain snowpack and glaciers. The region is experiencing a significant temperature rise which is projected to continue potentially threatening agricultural production. This study models impacts of climate change on agricultural production and water use in SEK with a focus on maize production on irrigated farmland. This is the first study modelling crop responses to climate change in the region and as such, it initiated collection of data required for modelling. For this reason, modelling is conducted at field scale. Two water - crop models, AquaCrop and SALTMED, have been set up, calibrated, and validated using the data from the 2016-2019 growing seasons. The statistical metrics used to evaluate model performance under the present climate confirm robust performance of both models. Future projections of growing cycle, crop water requirement, and maize yield have been developed for the Representative Concentration Pathways (RCP), RCP4.5 and RCP8.5, for the future time slices of 2020 - 2049, 2040 – 2069, and 2070 – 2099 using data from several Global Circulation Models, which have been downscaled and bias corrected. The results from both crop models indicate that growing cycle is expected to be shortened by up to 50 days by 2100. This significant reduction is mainly associated with a strong climatic warming projected for the growing season. The shortening of the growing cycle can lead to a reduction in crop water requirements which are projected to decline by 16-24% and 11-15%, using SALTMED and AquaCrop, respectively, by the end of the 21st century. Maize yields are projected to decline by 11.2 % and 6.8 % in the AquaCrop and SALTMED simulations, respectively. The developed projections can be used to inform the development of adaptation strategies and practices by individual farmers and regional decision-makers contributing to the development of adaptive capacities and promoting farmers’ resilience to future climate change in SEK. Adaptation measures can include changing planting dates, irrigation practices, and using new cultivars adapted to higher temperatures and shorter growing season.