Publications

Kang, M; Hao, Y; Choi, M (2023). The effects of flash drought on the terrestrial ecosystem in Korea. JOURNAL OF HYDROLOGY, 624, 129874.

Abstract
Typified by rapid intensification in a short time, flash droughts (FDs) have attracted increasing attention because of their effects on water resources and ecosystems. Water use efficiency (WUE) is a key indicator for understanding the interaction between the carbon dynamic and water cycle. However, the effects of FDs on terrestrial ecosystems in Korea remain mostly unknown. Therefore, we identified FD events in Korea using the soil moisture (SM)-based rate of intensification (RI) and the evapotranspiration (ET)-based Standardized Evaporative Stress Ratio (SESR) with flux tower data. Continuous satellite data from the Moderate Resolution Imaging Spectroradiometer (MODIS) were used to examine spatiotemporal patterns and trends in FD-related factors, Potential ET (PET), Actual ET (AET), Gross Primary Productivity (GPP), Evaporative Stress Ratio (ESR), and WUE from 2001 to 2020. The frequency, duration, and intensity of FDs in Korea were investigated and responses in WUE to FDs in different landcover types were examined. The SESR and RI had a similar performance in capturing FD events in flux tower site data. At the regional scale, a lower ESR was mainly observed in the western and southern parts of the study area, indicating progressively drier climate conditions. The mean frequency percentage and number of Korean FD events in the past 20 years were 61.3% and 16, respectively. In addition, more FD events occurred in the northern and eastern regions of the study area, where the main landcover type is forest, and northeastern Korea suffered from long FD events (over 30 days). FDs caused a positive response of WUE in most of the study area. However, the change in WUE after FD events varied by FD severity and landcover type. The changes in WUE after moderate FD events were largely driven by the change in GPP, and the highest sensitivity of WUE to FD intensity was found in croplands. These findings highlight the characteristics and effects of FDs on WUE across landcover types, which will be helpful in managing potential environmental risks in Korea.

DOI:
10.1016/j.jhydrol.2023.129874

ISSN:
1879-2707