Modelling impact of agro-drought on grain production in China

Agro-drought is a powerful natural force shaping significant impacts on food security in a country like China with huge population and relatively limited cropland resources. Quantitatively modelling the relationship between agro-drought and Chinese grain production had not been reported in scientific literature. In this paper we developed an applicable approach to model the impact of agro-drought on grain production in China using the statistical data on agro-drought at various levels of severity. Our hypothesis was that grain production in China should be higher than the actual one shown in statistical yearbooks for the same cropping structure and farming inputs if there was no drought. To test the hypothesis, a modelling procedure to link agro-drought at various levels with grain production had been established at provincial level of China. Statistical data on agro-drought and grain production with consideration of cropping structure were used for the modelling. Our results indicated that the impact was very obvious. Each year ~24 Mha (million hectares) of cropping land in China were under drought attacks at various levels. Average drought intensity defined as ratio of grain acreage under drought attacks to total grain acreage was 13% during 1990–2011 taking moderate attack as a unity, which is defined as grain loss of ~45% under drought attack according to statistics system in China. Annual loss of grain production as a result of drought attacks was ~26 Mt (million tons), shaping an impact of 5.2% to grain production in China. The loss is almost equal to the total grain production of such a big grain producer as Hebei, Jilin or Hunan in China and can feed ~75 million people. Spatially intensive impacts of agro-drought on grain production were observed in northeastern, northwestern and southwestern provinces, where drought intensity was higher than 15% and the impact was over 6%. Our study reveals that food security of China under drought attacks is with a probability of above 92% and grain storage of ~20 Mt is required for China to minimize the threat of drought attacks on its food security. This significant impact of agro-drought on grain production might suggest the risk for Chinese food security that needs to be globally concerned under circumstance of climate change.