Responses of ET and GPP to Climate Variability and Management over the North China Plain

English Abstract:

Insufficient water resource is a major constraint on sustainable development of agriculture and socio-economy, and an imminent threat to national food supply security. Strategy and policy of regional water management demand reliable prediction of areal evapotranspiration (ET) and water use efficiency (WUE). Here the process-based VIP eco-hydrological model integrating remote sensing information are applied to predict areal ET and crop productivity (GPP) over the North China Plain (NCP) from 1981 to 2012. Results show that latitudinal gradient pattern was quite noticeable for both ET and GPP distribution, especially in winter wheat growing season. With respect to water resources deficits, it is revealed that fields with ET higher than precipitation are mainly located in the north of Yellow River, while the southern NCP showed a rainfall surplus at annual level. It is found that both annual ET and GPP are increasing during the study period. Affected and regulated by both climatic variability and crop responses in terms of vegetation growth and phenology, both ET and GPP illustrate noticeable inter-annual variability. The contributions of climate change, atmospheric CO₂ enrichment and human activities to ET and GPP trends are separated. The estimated ET and water use efficiency (GPP/ET) are used to assess the suitability of crop system under the current conditions of climate and water resources availability, and some adapted cropping pattern and systems are suggested for policy decision.