## 4 Discussion  
In recent years, despite increased attention and management efforts towards mitigating heavy rain disasters in the studied region, the proportion of direct economic losses from heavy rain disasters remains high relative to other meteorological disasters. We believe the reasons may include the following:  
1. Between 2000 and 2010, the areas classified as relatively high and high-risk zones accounted for 40-50% of the total area, primarily located in southern and eastern Hebei Province and Beijing. This may be due to low density of drainage network construction, frequent industrial activities, high density of factory buildings, and inadequate planning, design, and management of flood control and drainage facilities during this period. These issues led to the drainage systems operating beyond capacity, with rainfall intensity in some areas exceeding the design standards of drainage pipes, resulting in widespread waterlogging and flooding of main roads, severely disrupting transportation and causing extensive heavy rain disaster losses. 2. In 2012, the Beijing-Tianjin-Hebei region experienced a three-day extreme heavy rain event. Assessment results showed that the persistent rainfall significantly impacted medium and relatively high-risk areas, which were highly concentrated in Qinhuangdao, Tangshan, Baoding in Hebei Province, Tianjin, and southeastern Beijing. These areas, located on the flat and low-lying North China Plain, suffered from inadequate planning and construction of flood control and drainage facilities, incomplete urban drainage systems, and prominent issues of drainage network aging, damage, and siltation. These factors slowed rainwater infiltration and significantly increased surface runoff, exacerbating the extent of heavy rain disaster losses. This also exposed deficiencies in the disaster prevention and mitigation systems and the collaborative control capabilities of engineering facilities in response to extreme precipitation events, causing severe disruptions to urban transportation and residents' lives. 3. In 2016, high-risk zones in Hebei Province emerged in the foothill areas at the junction of the North China Plain and the mountains, such as western Handan, western Shijiazhuang, central Xingtai, and east-central Chengde. This may be due to the obstructive and uplifting effects of mountainous terrain, which caused intense surface runoff to form in local areas during heavy rain, quickly converging into mountain streams and leading to road collapses, landslides, and other disasters, significantly elevating the risk levels of heavy rain disasters in these regions. Additionally, based on disaster risk assessment results, high-risk zones for heavy rain disasters mainly appeared in river networks such as the Ziya New River, South Canal, and Chaobai River, as well as in southeastern floodplain areas. This spatial distribution is closely related to regional topography: on one hand, these areas are located in low-lying alluvial plains with poor drainage conditions; on the other hand, some upstream areas have mountainous terrain, where intense rainfall causes mountain floods to rapidly flow downstream, creating significant flood overlay effects. This hydrological process not only increases downstream disaster risk but also causes losses to agricultural production and other socio-economic systems. Risk assessment results form the basis for devising measures to reduce disaster risks. To mitigate future potential risks, it is essential to proactively implement disaster prevention and mitigation measures based on the assessment results to minimize losses. Based on our analysis of heavy rain events and disasters, we suggest the following strategies to reduce risk and enhance response capabilities:  
1. In urban planning and management, strengthen the construction, renovation, and risk assessment of flood control and drainage facilities to improve infrastructure quality. 2.