Temporal distribution and trend prediction of agricultural flood and drought disasters in China

This article analyzes the temporal distribution characters of agricultural flood and drought disasters during the period from 1970 to 1999 in China. It can be seen from the analysis that agricultural natural disasters increased in the research period. Two phases can be evidently indicated: total disasters and flood and drought had lower harm to agriculture before the middle of 1980s; great disaster, influenced area and losses increased evidently after the middle of 1980s. Drought and flood were the more harmful natural disasters to agriculture and drought was the most in particular. The area suffered from drought were not changed in general. The ratio of drought-affected area fluctuated evidently and the ratio of disaster-suffering area increased year after year. This trend may relate to the slow development of farmland irrigation facilities. The ratio of flood-affected area was synchronous with the ratio of the disaster-suffering area. It shows that flood can easily causes disaster once it happens. The increase of harmfulness caused by flood may attribute to the lower capacity of protection and the deterioration of eco-environment. The ratio of suffering area and the ratio of affected area for all kinds disasters are positive correlative. This indicates the resistance capacity of agriculture system in China is faintish in general. Based upon the gray system method, models are established for predicting the ratios of affected area to suffering area in agricultural total disaster, flood and drought, and their trends in the future ten years. Gray modeling results indicate that heavy disasters will occur in all the ten years except for 2003 and 2006. The ratios of disaster affected area and of disaster suffering area will be over the average levels in the past 30 years. Great flood will happen in 2004 and 2007, and drought and flood will occur simultaneously in 2002 and 2009.