Simulating potential response of hydrology, soil erosion, and crop productivity to climate change in Changwu tableland region on the Loess Plateau of China

Knowledge of the impacts of climate change on agro-ecosystems is needed for developing optimal conservation and production practices. The objective of this study was to evaluate the potential impacts of projected climate changes during 2070-2099 under three emissions scenarios (A2a, and B2a, and GGa1) on hydrology, soil loss, and crop production in Changwu tableland region on southern Loess Plateau of China. Monthly projections for the periods of 1950-1999 and 2070-2099 were used from the Hadley Centre's general circulation model (HadCM3). A stochastic weather generator (CLIGEN) was used to downscale monthly HadCM3 projections to daily values at three spatial scales. The Water Erosion Prediction Project (WEPP) model was run for a wheat-wheat-maize rotation under conventional and conservation tillage at the 8.7% and 17.6% slopes. HadCM3 predicted a 23-37% increase in annual precipitation, 2.3-4.3 °C rise in maximum temperature, and 3.6-5.3 °C rise in minimum temperature for the region over the century. Compared with the present climate, predicted percent increases under climate changes, as averaged over the three spatial scales for each emissions scenario and slope, ranged from 29 to 79% for runoff, 2 to 81% for soil loss, 15 to 44% for wheat grain yield, 40 to 58% for maize yield, 25 to 28% for crop transpiration, 21 to 34% for soil evaporation, and 4 to 12% for long-term soil water reserve under the conventional tillage. However, adoption of the conservation (delayed) tillage could reduce runoff by 18-38%, and decrease soil loss by 56-68% as compared to the conventional tillage under the present climate. These results suggest that the use of the conservation tillage would be sufficient to maintain low runoff and erosion levels and thus protect agro-ecosystems under projected climate changes.