Development of Alarm Grit Ratio for Drought Forecasting and Its Application to the 2021–2023 Drought

The frequency and severity of droughts are increasing due to climate change and environmental disturbances brought on due to human development, making drought warning an essential tool in mitigating their effects. Drought warning can, however, be easily overlooked if people disregard its significance or repress water managers with the result of the drought warning. Therefore, in the current study, we developed an Alarm Grit Ratio (AGR) for drought warning to assess how active these have been thus far, and was estimated the ratio for the current drought in Korea from 2021 to 2023. The Korea Meteorological Administration issued three drought warnings, which were classified as agricultural, meteorological, and residential and industrial droughts. We proposed two indices to indicate how an institution issues a drought warning as a forecast for the actual drought warning that follows. These indices were AGR and Transitional Alarm Grit Ratio (TAGR). AGR measures how frequently an institute issues a drought warning forecast based on the number of actual warning conditions. Analysis of the current drought (2021–2023) indicates the issuance of warnings, while TAGR indicates the ratio of the drought warning issuance at each drought. The AGR and TAGR for the agricultural and meteorological droughts indicate underissuance of drought warnings, whereas warnings for residential and industrial droughts were appropriately issued due to the drought impact on residences and industries. Overall, we concludes that AGR and TAGR can be useful indicators of how actively an institution issues drought warnings. An institution in charge of drought warning can track these measurements and control the frequency of drought warnings by including AGR and TAGR data.