Hydrological drought assessment in Nam Oon basin based on Streamflow Drought Index (SDI)

Abstract

Drought is a widespread natural phenomenon throughout. It occurs at a time when streamflow availability in the watershed shows a trend that is lower than the annual average, causing insufficient demand and affecting the reservoir's water resource management. The objective of this study was to determine the occurrence of hydrologic drought related to streamflow using the Streamflow Drought Index (SDI) of the Nam Oon Reservoir in Sakon Nakhon Province. The SDI values were calculated over time periods of 3, 6, and 9 months, comparing the upstream area above the reservoir and the downstream area of the reservoir with regulating over water allocation. The results of hydrological drought analysis using SDI in both areas showed trends in the same direction. At site station of dam and station KH108, HK54. The number of months of drought-phenomena at station KH108 ranged between 55.32% -65.91% of time periods 6 months. The SDI values were mainly expressed in Mild Drought between 21.8%-33.9%. In addition, the SDI at the upstream area illustrates a higher chance of drought than the downstream area due to reservoir management. The methodology and results obtained from this study are expected to be used as statistical data for decision-making in drought mitigation planning during the recurrence period in the watershed area.