STATISTICAL ANALYSIS OF ATMOSPHERIC CONDITIONS FAVOURING EXTREME PRECIPITATION AND FLASH FLOODS (CASE STUDY: SUMATRA 2011 - 2021)

• Main Author: Nabila Fadiyah, Nurul
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/74889
• Institution: Institut Teknologi Bandung

Sumatra is a region with frequent flash flooding problems. According to The Disaster Management Capacity of National Agency for Disaster Management (BNPB), there were 190 events of flash floods in Sumatra from 2011–2021. Atmospheric instability affects extreme precipitation which can trigger flash floods. However, studies regarding the increase in extreme precipitation and atmospheric conditions on the increase of flash floods have not been widely studied. Therefore, this study was conducted to identify and analyze atmospheric conditions that occurred during extreme precipitation and flash floods in Sumatra from 2011–2021. This study used the Generalized Extreme Value (GEV) method to calculate the threshold value of precipitation in a given return period according to the centroid of the flash flood events. Global Precipitation Measurement (GPM) data is used to calculate extreme precipitation values. Reanalysis ERA5 data for calculating proxy parameters are Convective Available Potential Energy (CAPE), Convective Inhibition (CIN), k-index, total column water vapor, specific humidity, relative humidity, wind speed, low level wind shear, and deep-layer wind shear. Three categories are used to identify the thresholds of each proxy parameter and selected which are sensitive in identifying triggers for extreme precipitation and flash floods. The results of this study during 2011–2021 on Sumatra were at least 93 flash floods events that generally occurred during the MAM season (March-April-May). The K-Index (? 28.3?) or Total Column Water Vapor (? 39.67 ???????? ?????2 ) parameter are sensitive proxy parameter in identifying triggers for extreme precipitation and flash floods rather than the Convective Available Potential Energy (CAPE), Convective Inhibition (CIN), specific humidity, relative humidity, wind speed at level 700 hPa, low-level wind shear, and deep-layer wind shear. The percentage of K-Index and Total Column Water Vapor parameters for flash floods events are 81.5% and 77.7% respectively.