Evaluating the disaster risk levels associated with “Dragon Boat Water” in Guangdong China

Abstract. Dragon Boat Water (DBW) is a period characterized by abundant precipitation and concentrated precipitation process in Guangdong province, China. The period often leads to severe flood disasters, resulting in substantial losses to both livelihoods and production. However, a comprehensive assessment of disaster risk during DBW has been lacking.

In this study, we utilized daily precipitation data spanning the years from 1995 to 2020, coupled with related disaster data from Guangdong. The Precipitation Comprehensive Intensity Index (PCII) and the DBW Comprehensive Disaster Index (CDI) were established. PCII and CDI were categorized into three levels using the percentile method. Moreover, we delved into the intricate relationship between these two indexes.

The results revealed that PCII falls into the three levels: extreme heavy, heavy, and normal, representing 19.2 %, 30.8 %, and 50 %, respectively, with the peak occurring in 2008. Meanwhile, CDI comprises three levels: high, medium and low, accounting for 19.2 %, 30.8 % and 50.0 %, respectively, with peak years closely aligning with those of PCII. Our calculations demonstrated a positive correlation between PCII and CDI, as well as between PCII and the occurrence of five types of disasters. Notably, heavier PCII levels had a more pronounce impact on crop damage, affected population numbers, and the direct economic loss, with the most substantial influence observed on the affected population. Though disaster data for 2022 has yet to be fully collated, based on PCII and CDI, we determined that 2022 experienced the fourth-highest precipitation and fifth-highest disaster level since 1995. This assessment concurs with the actual conditions observe in 2022. As a result, we propose that in the future, PCII and CDI can be invaluable tools for pre-disaster risk assessment, ongoing disaster monitoring, and expedited post-disaster evaluation.