Temporal and Spatial Distribution Characteristics of Flood Disasters with Different Intensities in Arid-Semiarid Region in Northern Xinjiang, China

Floods have devastating environmental and socioeconomic consequences. Flood disaster management is critical for the long-term management of water resources and agriculture in arid areas. Using the data on the number of deaths, destroyed homes, collapsed sheds, livestock deaths, and the crops affected area caused' by 1394 regional floods in Northern Xinjiang (As a typical arid-semiarid region of NorthWest China) from 1981 to 2019, the ratio-weight method and the dimensionless linear summation method was used to calculate the actual disaster damage exponent of flood disaster events. The damage exponent is further used to categorize the severity of disaster events into four grades: normal, moderate, severe, and extremely severe. The analysis results indicated that Bortala Mongolian Autonomous Prefecture experienced the highest frequency of catastrophic occurrences, while Ili River Valley experienced the highest intensity. The flood happened most often in Wenquan County. And Yining County suffered the worst calamity. The occurrence frequency and intensity of disasters from Grades 1 to 3 exhibited a unimodal distribution, with the majority and most vital occurrences in July, whereas the occurrence frequency and intensity of Grade 4 disasters followed a bimodal distribution, with the most occurrences in July and the strongest in April. The annual frequency of heavy rain and flood disasters in Northern Xinjiang increased by 7.7 times every 10 years, indicating a significant linear increase trend. The yearly occurrences of Grades 1 and 2 also increased linearly, by 5.2 and 2.0 times per decade, respectively. There was no linear tendency to increase or decrease flood disasters in Grades 3 and 4. The analysis and division of actual disaster damage are conducive to flood risk management, efficient prevention, and reducing disaster losses.