The trend of natural disasters in Iran in the last 100 years follows the global natural disasters trend. Globally, while from 1900 to 1980, fewer than 100 disasters are reported annually, the number of disasters in the period of 2000 to 2019 is between 300 and 400 disasters annually [49]. Natural disasters that were reflected in Iran’s budget allocation regulations have the same trend where both disaster frequency and the associated budget significantly rose until 2009. The increase in the frequency of natural disasters can be motivated by improved reporting by governments in addition to the emergence of anthropogenic climate change. The findings of this study show that the most frequent natural disasters in Iran in the last 100 years are floods, earthquakes, and droughts. According to Centre for Research on the Epidemiology of Disasters (CRED) [49], between 1970 and 2019, floods are the most frequent disaster in the world, followed by extreme weather conditions, droughts, earthquakes, landslides, and wildfires.
Floods are the most frequent climate-related disasters in the last 100 years in Iran, according to budget regulations and the second in the amount of budget (20%). Floods usually bring mass destruction associated with economic, physical, and social losses. Neglecting floods for governments is very difficult mainly because of the social pressure. Nevertheless, it could be hypothesized that the statistics of floods in the budget regulations are true. In Iran, heavy temporary rainfall, and in some regions, the combination with sudden snow melt are the main reasons for flooding. Heavy rainfall especially happens in the North of Iran (north of Alborz Mountains), Southwest (Zagros Mountain), south (near Persian Gulf), and South East (The Hirmand river) [29]. From 2015 to 2020, eight major floods occurred in Iran [29, 50,51,52]. The worst flood in Iran in a recent decade was in 2019 that affected to 26 provinces of Iran out of the total 31 provinces [51]. A flood in 2001 in Golestan province in the north of Iran was another major flood [29]. Floods are more predictable compared to other disasters, and mitigation and prevention have significant roles in risks reduction. For example, there were many articles discussing flood prone regions in Iran before the great flood in 2019 [53,54,55,56,57,58] which could have used by the Iranian government to prevent such high damages. However, mass destruction of infrastructure and allocating a significant amount of budget to flood affected provinces in 2019, is a proof for underestimating flood risks by the government [59].
According to the findings, earthquakes are the second disasters in both of frequency (25%) and budget (23%) during the last 100 years. West of Iran (along the Zagros collision) is earthquake prone because of the collision of Arabian and Eurasian plates. In addition, the south of Iran is along the Makran subduction is also seismically active [60]. Examples of tragic earthquakes in Iran can be seen in Qazvin earthquake in 1962, Khorasan earthquake (1948), Khakhk earthquake in 1968, Dashti Biaz earthquake in Khorasan province (in 1931,1941,1947, and 1962), Tabas earthquake (1978), Manjil–Rudbar earthquake in 1990, Bam earthquake in 2003, Kermanshah earthquake in 2017 [61,62,63,64]. In the budgeting in Iran during the last 100 years, two earthquakes were more significant, including Manjil–Rudbar earthquake in 1990 and Bam earthquake in 2003. As shown in Fig. 4, there are two jumps in government expenditures in 1990’s and 2000’s. These two jumps are related to two earthquakes in Manjil (1990) and Bam (2003).
Droughts are the most expensive disasters for the Iranian government in the last 100 years and more than 47% of disasters costs belongs to droughts. Drought is referred to water resources shortage over a large geographical area in a significant period [65]. Iran is an arid and semi-arid country. Despite of deserts, other regions of Iran are experiencing an increase in climate change toward less precipitation [29]. Drought is the most complex disaster and the least understandable one [66]. Iran is struggling with droughts for the decades, and therefore Iran must take key steps in addressing droughts. Most of expenditures related to droughts are dedicated to response. Nevertheless, in comparison to other disasters such as flood and earthquake, its frequency and visible devastation are slow, leading to less sensitivity of mass media and people. In contrast to other disaster types, there are not reliable reports from losses resulted from drought (economic, socially, physically). Thus, the reliability of drought budget allocation is very difficult. Two provinces including Isfahan and Sistan & Baluchistan gained drought-related budgets compared to other provinces. Many provinces in Iran, such as Yazd and Far, have been suffering from droughts during the last decades in the similar scale as the Isfahan and Sistan provinces [66]. For example, Yazd province, which is one the most drought-affected regions in Iran, is in the bottom of the list in terms of drought budget [67]. Unfortunately, budget allocation for drought disasters, is mainly related to political issues such as members of Iranian parliament, the share of this province in the power hierarchy, security issues, and media. Thus, an integrated energy-water-food analysis and management plans (such as that performed in [68]) are necessary in water management plans and drought mitigation plans in Iran.
In terms of disaster frequency based on budget allocation, top five provinces are Kerman (5%), Isfahan (5%), Gilan (4%), East Azerbaijan (5%), and Sistan Baluchistan (5%). However, it is not true to conclude that these provinces necessarily have experienced more disasters than other provinces. For instance, Gilan province experienced several floods during the last 100 years in addition to a devastating earthquake in 1990 that the Iranian government allocated a large budget for the response and recovery of that earthquake [69]. Kerman is the second province in terms of disaster budget allocation mainly because of earthquake frequency in this province. An enormous earthquake occurred in Bam city in Kerman province in 2003 is one of the deadliest earthquakes in this province that killed more than 26,000 [70].
Due to climate change, the current resources such as facilities, water consumption policies and technologies, and construction standards are not enough to response to disasters under climate change such as drought, flood, and extreme weather. Thus, Iran must invest more into preparing it infrastructures for the coming disasters [71]. More importantly, the disasters stemmed from climate change are not solo events. Climate change related disasters are strongly coupled and act as dominos. For example, drought and heatwave occur together. Drought leads to dry soils and as a result, solar energy from evaporation will end to increase surface warming and consequent increased evaporation rates [72]. Drought and heatwave will increase the risk of wildfires. Furthermore, sandstorms, haze, and water conflicts are other consequences of drought. Iran, like many other countries, has a disaster management plan as an isolated event and a solo hazard, while it should be managed as cascading hazards [72]. A cause of increasing cascade effects of major disasters is critical infrastructure failures such as transportation, water supply, energy, and communication [14]. Infrastructure and hazards are correlated and failure in providing through infrastructures enhances disasters’ impacts while disaster lead to failure in infrastructures. This interrelationship makes a vicious cycle or trap that if not addressed properly, its impacts will be bigger and bigger like an avalanche in many unprepared countries including the disaster-prone unprepared Iran.