Peak drought severity time analysis of Cheongmicheon watershed using meteorological and hydrological drought index

This study analyzed the peak drought severity time of the Cheongmicheon watershed according to evaluation period based on 1) Past (period from 1985 to 2015) and 2) Future Climate Change scenarios (RCP 4.5 & 8.5 period from 2011 to 2100). In order to assess the peak drought severity of lag time and relationships between various drought indices, we used meteorological and hydrological drought index. Standardized Precipitation Index (SPI) was based on precipitation and Standardized Precipitation Evapotranspiration Index (SPEI) was based on precipitation and
evapotranspiration, were applied as meteorological drought index. Stream Drought Index (SDI) based on Runoff data was applied as hydrological drought index. In the case of SDI, we used Soil and Water Assessment Tool (SWAT) model for simulation of daily runoff data and SWAT Calibration and Uncertainty Procedures (SWAT-CUP) for optimization of SWAT parameters. In order to analyze the relationship between meteorological and hydrological drought index, SDI was selected in the case of less than -1.5. We compared SPI, SPEI and SDI’s peak drought severity time. As a result, in case of RCP 4.5, the differences of peak drought point between SDI and SPI and between SDI and SPEI were 0.8 months and 0.54 months. In case of RCP 8.5, the differences of peak drought point between SDI and SPI and between SDI and SPEI were 0.89 months and 0.99 months. As the duration was increased, the frequency of drought was decreased. This confirmed that SPEI gives a significant impact on SDI more than SPI.