Impacts of climate change and adaptation in agricultural water management in North China.

Abstract Water scarcity is one of the key problems in northern China. Efficient use and management of agricultural water resources is an important challenge in China's agricultural food production under a background of climate change. This chapter addresses issues of impacts of climate change and adaptation in agricultural water management in North China. The goal is to understand better the impacts of climate change on agricultural water resources and what measures should be taken to deal with the adverse effects in the North China Plain (NCP). First, the status of agricultural water resources in NCP was analysed. Second, considering that climate change is likely to exacerbate water stress in this area, and exploring the regional crop response to climate change, this study analysed the spatial variability and evolution of crop yield, evapotranspiration (ET) and water use efficiency (WUE) with a process-based crop model in the NCP and identified the contribution of climate change to their enhancement. Third, the impacts of future climate changes under A2 and B1 scenarios (described later in this chapter) on the wheat-maize double-cropping system are assessed. The results show that under IPCC SRES A2 and B1 scenarios, production of winter wheat will increase with slightly intensified ET; in contrast, summer maize production will slightly decline with a significant increase of ET. Also, with agricultural management, maize is more productive than wheat, in that wheat relies more on irrigation than maize, yield level of maize is higher than that of wheat, the water consumption of maize is lower, and the response of maize yield is larger than that of wheat yield to agricultural management. However, the simulation also suggests that wheat is more resilient to climate change than maize. Therefore to say if wheat or maize is more favourable in the NCP depends on the conditions in the future. Finally, in order to mitigate the impacts of climate change on agricultural water use and realize its sustainable utilization, the key adaptive water management strategies in the agriculture sector and how to improve efficiency of agricultural water use through reforming agricultural water management and policies were examined. The following measures can be implemented to reform agricultural water management and policies: improving the performance of participatory irrigation management reform, establishing a water rights system, reforming agricultural water price, and promoting the adoption of agricultural water-saving technology.