Brief Report

Starting from August 6, 2022, a phenomenon characterized by sudden and heavy rainfall, severe lightning, and dust storms became active in various regions of Iran, resulting in significant loss of life and property. ² Recent monsoon rains of summer 2022 until the middle of August almost caused the death of more than 90 people ⁶ and affected approximately 136 cities, 958 districts, 133 counties, and 1344 villages across Iran. ⁷ Among the areas most severely impacted by this phenomenon was the Imamzadeh Davood recreational pilgrimage site located in the northwest of Tehran, Iran (latitude and longitude: 35.87677, 51.33744). This area has a seasonal river that passes through the middle of houses and Imamzadeh by a concrete waterway (Figure 1).

Figure 1. Imamzadeh Davood area and its seasonal river.

On August 6, 2022, at 1:30 PM, there was a heavy rain that lasted for 20 minutes, followed by a massive flood in the Imamzadeh Davood area. The flood originated from the north side of Imamzadeh place and the old bazaar, passing through restaurants and various shops from 2 locations—the main entrance of Imamzadeh and the passage of the water channel under the Imamzadeh building. The flood destroyed the roof of the river, which was located under Imamzadeh, and entered the courtyard of Imamzadeh, causing significant human injuries and financial damage. Unfortunately, 24 people lost their lives in this area (Figure 2).

Figure 2. Imamzadeh Davood after the flash flood (A, B, C, D).

Official reports, field evidence, and documents indicated that some of the causes of these tragic deaths following the 20 minutes of heavy rain were as follows:

• Failure to learn from previous events. Historical records reveal that in 1954, a similar sudden rainfall and ensuing flood transpired at the same location, resulting in the complete devastation of Imamzadeh and claiming the lives of over 500 individuals within the courtyard and over 2000 people along the flood path (Supplementary 1: Figure 1). One crucial aspect of emergency and disaster management is the use of lessons learned from past incidents. If the lessons learned from the previous event had been taken seriously at this location and implemented to reduce the risk of disasters, the health, economic, and social consequences of this incident may have been less severe.

• Inadequacy of certain aspects of the emergency and disaster management program. Despite having accurate weather forecasts predicting the occurrence of sudden monsoon rains, weaknesses in various processes of the disaster management program, including some aspects of the early warning system and prompt evacuation of people at risk, were evident. In this incident, there was a lack of proper notification to those at risk, failure to evacuate on time, and failure to observe traffic restrictions in high-risk areas. An effective early warning system is critical for disaster management. According to the World Health Organization, the first component of the response plan is to establish a comprehensive early warning system that operates simultaneously to notify those at risk before exposure to the hazard. The system comprises 4 parts: risk knowledge, monitoring and warning, communication, which is the core of the system, and response capability. It is essential to note that the notifications sent by the early warning system should be clear, understandable, and disseminated to all individuals who are at risk.

• Lack of proper emergencies and disaster risk perception and insufficient investment in reducing the risk of incidents. As previously noted, the physiography of this area indicates that it is prone to repeated floods, and this region is considered high risk. Despite the historical records of floods in this region and its high vulnerability, there appears to be inadequate risk perception among both the exposed population and regional authorities to prevent disasters and minimize the damage caused by floods. Moreover, scientific and practical investments to mitigate the impact of floods in this region have been insufficient, based on the historical records of floods and the occurrence of new climate events. It is crucial to prioritize scientific and practical investments based on evidence to reduce the risk and minimize the damage caused by floods in this region.

• Lack of respect for the waterway boundary by human intervention and unauthorized construction in the river. ⁸ As evident in the descriptions and pictures, the disregard for the boundary of the river and unauthorized construction for personal gain was one of the primary causes of this incident.

• Inadequacy of watershed and aquifer management plans to manage the type and intensity of risks in the region. ⁹ Evidence and reports suggest that several flood control projects have been implemented in the past in the watershed and seasonal river of this region, which were successful in controlling a significant volume of floods. However, the tragic outcomes of this flood indicate that this level of activity was not effective and needs to be reviewed and strengthened in light of the type of hazards, vulnerable points and factors, and the level of risk posed by regional hazards. It is crucial to develop and implement effective watershed and aquifer management plans that consider the intensity and type of risks in the region to minimize the damage caused by floods.

• The last contributing factor was the seasonal river’s capacity and route not corresponding to the risks in the region, including all risks and consequences. ¹⁰ One of the other causes of this incident is the blockage of the seasonal river in this area with the destroyed remains of some stone-mortar and gabion dams of the seasonal river, the flow of mountain erosion remnants in the water path, and a car that entered the flood from the upper reaches of the river. These factors caused an obstacle in the way of water flow, rising water, destruction of water channel, and, ultimately, water entering the Imamzadeh courtyard and surrounding buildings.