Temporal and spatial variation of rainstorms and the impact of flood disasters due to rainstorms in China in the past 25 years

Rainstorms have a high frequency and flood disaster is one of the major natural hazards in China. Extreme precipitation events are projected to increase in frequency and intensity in the future according to the results of global climate models. Based on survey data of floods at county-level and daily precipitation data at weather stations, the temporal-spatial variation of rainstorms and the consequences of floods caused by rainstorms were analyzed for last 25 years. Meanwhile, the change trend of the flood consequences and its regional difference were highlighted. The results suggest that the range of rainstorms was increasing on the scale of country. It shows a spatial pattern of greater in the Southeast than in the Northwest for the intensity of rainstorms. The mid-late 1990s was a high-frequent period during this research period. The direct economic loss of floods due to rainstorm floods had an increasing tendency, but the ratio of direct loss to the annual Gross Domestic Product (GDP) was decreasing. The loss amounts are evaluated at 57.3 billion Yuan per year over the period. These higher loss counties were mainly located in southern China because of higher frequency of rainstorms and more prosperous economy. In China, the counties where the per year loss amounts exceed 20 million Yuan got about 15% loss of the total. There were 34 counties at more expensive loss, which per year amounts exceed 100 million Yuan. During the period, the total population who suffered the flood caused by rainstorms was increased. However, the death toll was in decline.. It reflects the capacity to coping flood disasters has improved. Our results also show that agriculture was affected greatly by rainstorms and flood disasters, both the affected areas and devastated areas have slight increasing trends in the period. The annual mean areas of cultivated land influenced by rainstorm floods were nearly 9 million hm², and the fail areas were 1.3 million hm², which is consistent with the increasing trend of rainstorms. This research not only displays the impact of rainstorms and floods in the temporal-spatial patterns which have high consistency of the pattern of rainstorms, but also suggests climate change and human activities do have impact on the consequences of floods. More attention should be paid on climate change adaptation and disaster risk management of floods in the future.