*3.6. Crop Yield Analysis*

This study analyzed the impact of climate change on crop yield in the Olifants catchment. The WEAP-MABIA model was used to simulate crop yield under RCP 4.5 and RCP 8.5 emission scenarios. Results presented in Table 5 show the changes in crop yield for both RCPs climate change scenarios relative to the 30 years baseline average. Based on the analysis, an average annual decrease in crop yield was expected for both projected climate change scenarios (RCP 4.5 and RCP 8.5) for the early, mid, and end-term periods with RCP

8.5 showing the highest rate of decrease towards the end of the century. A decrease of 19 to 40%, 12 to 25%, 19 to 32%, and 5 to 20% was anticipated for maize, soya beans, dry beans, and sunflower under the RCP 4.5 climate change scenario. For the RCP 8.5 scenario, maize and soya beans were expected to decline by 20 to 65% and 11 to 38% respectively, while a decrease of 16 to 42% and 10 to 30% was expected for dry beans and sunflower. A slight increase in the yield of soya beans in the early term for RCP 8.5 was anticipated. The general decrease in crop yield in the Olifants catchment is attributed to the decreasing trend in precipitation coupled with an increase in temperature. The anticipated decline in crop yield in the catchment suggests the need for the development and implementation of plausible adaptation measures.

**Figure 6.** Influence of soil texture on crop yield, a plot showing crop yield response to different soil water holding capacity resulting from soil characteristics.

**Table 5.** Changes in crop yield (in t/ha) for RCP 4.5 and RCP 8.5 emission scenarios relative to the average 30 years historical baseline (1976–2005).

