[Reading Science] Today's Spring Rain Falling Is Worth 1 Trillion Won

Increased Value of Spring Rain Due to Spring Drought and Worsening Air Pollution
Significant Effects on Water Supply, Fine Dust, Wildfires, and Agricultural Products

"Today's spring rain is worth '1 trillion won.'

On the 5th and 6th, when the country was suffering from a long drought and large-scale wildfires, a welcome spring rain fell nationwide. On Saturday the 15th, spring rain was forecasted with around 5mm in the metropolitan area and 40mm in the inland areas of Gyeongnam. Such spring rain is becoming an increasingly precious guest. Due to climate warming, extreme weather events are becoming 'commonplace,' worsening spring droughts and wildfires, while fine dust from China is also rampant, causing the marginal utility people feel from a single spring rain to surge rapidly. So, how much economic value does spring rain actually hold?

On the 9th, with showers falling across various inland areas, citizens hurried their steps on the streets near Yonsei University in Seodaemun-gu, Seoul. Photo by Mun Ho-nam munonam@

The most recent official research data analyzed the economic value of the spring rain that fell on March 31, 2015, by the Korea Meteorological Administration's National Institute of Meteorological Sciences. Although some time has passed, it is possible to estimate the current situation based on those figures. At that time, since December 2014, regions such as Gangwon Province and other central and northern areas had been suffering from severe drought. Rainfall was only 20-40% of the average, with no rain for several months. On March 31, an average of 4.5mm of rain fell nationwide. Farmers anxious about drought before the farming season, industries troubled by water shortages, the entire population suffering from fine dust, and firefighters working hard to suppress and prevent wildfires all breathed a sigh of relief.

At that time, the National Institute of Meteorological Sciences evaluated that even the mere 5.5mm of spring rain had an economic value of as much as 250 billion won. The average nationwide fine dust concentration decreased by about 68.3㎍/㎥, resulting in an air quality improvement effect worth approximately 230 billion won. Additionally, 241,058 households escaped drought damage such as water restrictions, generating about 7 billion won in benefits. In terms of securing water resources and wildfire prevention, values of about 3.27 billion won and 300 million won respectively were generated. However, the value of that spring rain was not limited to 250 billion won. Since the rainfall was so small, only minimal effects were calculated, and items difficult to quantify such as the growth of crops, trees, and plants were excluded. Medical cost reductions due to improved air quality, indirect costs from wildfire damage, effects from water quality improvement, and urban temperature reduction effects were not accounted for. Also, the calculation was based on rain that fell only for one day, minimizing the amount of secured water resources.

[Image source=Yonhap News]

The spring rain on the 5th and 6th also fell under similar circumstances, relieving the public. Due to persistent clear and dry weather, the average temperature in March was the highest since 1973. The number of rainy days was 3.7, 4.3 days fewer than average, worsening the drought. As a result, in Jeollabuk-do, the average reservoir storage rate was 58.7%, about 20 percentage points lower than the average storage rate of 78.5%. An emergency situation was expected around July due to the depletion of agricultural water.

The forest also dried out severely, and before the spring rain fell, wildfires were rampant. On the 2nd, Inwangsan in central Seoul caught fire. Large wildfires simultaneously broke out in Hongseong and Geumsan in Chungnam, Seo-gu in Daejeon, and Hampyeong and Suncheon in Jeonnam, causing tremendous damage including the destruction of forest areas equivalent to 875 soccer fields and some houses. In this regard, the National Institute of Forest Science announced a study in March 2021 showing that if 5.5mm of spring rain falls, it can prevent wildfires for 1.1 days, which has an economic value of up to 12.1 billion won. Since wildfire damage is concentrated in spring, the utility value of spring rain is high. In fact, over the recent 10 years from 2011 to 2020, wildfires occurring during the spring wildfire caution period accounted for 66% (3,110 cases) of all wildfires and 93% of the damage area (35.8 times the area of Yeouido).

The economic value estimation study of artificial rainfall published in 2010 also indirectly estimates the utility of spring rain. This study analyzed that in the Andong and Imha Dam basins, representative areas with insufficient rainfall in Korea, artificial rainfall could secure 348 million won annually in water resources, prevent wildfires worth 22.458 billion won, and reduce drought damage worth 28.458 billion won. The air quality improvement effect for the metropolitan area due to artificial rainfall was estimated at 5.689 billion won.

Moreover, as climate extremes intensify, spring droughts and wildfires are becoming more severe, increasing human and property damage such as firefighting helicopter crashes. Public health costs due to fine dust are also becoming increasingly serious. Considering these factors, experts analyze that the economic effect of a generous day of spring rain can nowadays be estimated at around 1 trillion won.

[Image source=Yonhap News]