After the heat wave, drought has gripped the southern region, spreading damage from shortages of agricultural, domestic, and industrial water to algal blooms. Experts diagnosed this as a compounding disaster caused by climate change that has altered the way rain falls. They noted that when long dry spells and short, intense downpours repeat, it is difficult for the existing water management system to respond to drought and flooding at the same time.
According to the Korea Meteorological Administration on the 6th, nationwide precipitation in July was 72.3% of the norm. In particular, South Gyeongsang Province saw only 21.9% of its usual rainfall, making it the driest July on record. In mid-month, meteorological drought centered on the Gyeongsang region gradually expanded to the Jeolla region.
Guk Jong-seong, a professor in the Department of Earth and Environmental Sciences at Seoul National University, said, "This southern-region drought shows not just a temporary lack of rain, but that the way rain falls itself is changing after climate change." He explained that as dry spells lengthen while rainfall, when it comes, arrives as short, intense cloudbursts, the likelihood of alternating droughts and downpours could grow.
Even if a lot of rain falls at once, drought does not immediately ease. Rain that pours down in a short time tends to run off into rivers and the sea before it can sufficiently seep into the ground or be stored in reservoirs. By contrast, when rainless periods lengthen, soil moisture declines, raising the risk of shortages of agricultural and domestic water.
Cho Cheon-ho, former head of the National Institute of Meteorological Research, said, "The number of rainy days is decreasing while downpours are increasing, intensifying the temporal concentration and intermittency of precipitation," adding, "Even as total rainfall increases, drought risk is also growing—the so-called 'getting wetter yet drying at the same time' paradox is becoming a characteristic of Korea's summer climate."
This situation also shows the features of a "drought–heat wave compound disaster," in which heat and drought interact and worsen damage. When soil dries, less energy is used for evaporation, and more heat warms the surface and the air. The higher temperature, in turn, depletes soil moisture faster, worsening the drought.
Yeo Sang-uk, a professor in the Department of Climate and Energy Systems Engineering at Ewha Womans University, said, "Heat from ground surfaces baked by drought is strengthening the heat wave, and the intensified heat wave is again depleting soil moisture at the surface."
He went on, "In recent years in Korea, the frequency of compound disasters in which drought and heat waves occur simultaneously or consecutively has surged since the 2010s," emphasizing, "We need to improve the accuracy of compound-disaster forecasts and build a separate risk alert system."
◇ "Managing floods and droughts separately has limits… Water management must change to match altered rainfall"
Experts also said existing water resources policy, which has treated droughts and floods as separate disasters, must change. Quickly channeling water to the sea to prepare for floods can increase vulnerability to a subsequent drought. Conversely, storing as much water as possible to prepare for drought can raise the risk of inundation during sudden downpours.
Cho Cheon-ho, former head of the National Institute of Meteorological Research, said, "Droughts and floods are no longer separate disasters in Korea," adding, "We need a new water resources paradigm that treats floods and droughts as one continuous system and responds to the speed and magnitude of precipitation variability itself."
There was also a proposal to move away from water management based on past average precipitation and instead consider regional rainy-day counts, the intensity of heavy rains, and changes in soil moisture together.
Guk Jong-seong, a professor in the Department of Earth and Environmental Sciences at Seoul National University, said, "We must reflect climate outlooks in medium- to long-term national disaster mitigation policies such as dam and reservoir operations, allocation of agricultural and industrial water, and expansion of urban drainage and retention facilities," adding, "Policy benchmarks should be redesigned not to the past average climate but to the changing characteristics of precipitation."
Gu Ja-ho, a professor in the Department of Atmospheric Sciences at Yonsei University, said, "Meteorology and climate, architecture and civil engineering, and health and environment experts need to discuss more deeply than before how to build cities that secure more domestic water," proposing, "Cities should process and provide information so residents can easily see the amount of water resources secured, and build systems and platforms to prepare in advance for emergencies."