ASSESSMENT OF DROUGHT INDICES AND WATER AVAILABILITY USING STATISTICAL Z-SCORE AND MOCK MODEL

Abstract

The phenomenon of drought and water scarcity due to climate change is a major problem in many countries. Assessing drought conditions and water availability in a watershed helps the government and communities implement sustainable watershed management. The study was conducted in Krueng Jreue Sub Watershed, Krueng Aceh Watershed, Aceh Province, Indonesia. The meteorological and hydrological indices in the watershed were analyzed using statistical Z-Score for Precipitation (ZSP) and Discharges (ZSD). Discharges originated from Mock model was used to examine the water availability in a watershed. The results showed the ZSP and ZSD indices from 2008 to 2017 were almost categorized as normal. In certain months, drought indices with the criteria of extreme wet (EW), very wet (VW), and severe drought (SD) also occurred. In general, the ZSP and ZSD indices were consistent, but for certain months (April 2008, November 2010, and March 2017) inconsistencies were found due to differences in signs and index classes. The Mock model parameters for the proportion of surface soil uncovered by vegetation (m), infiltration factor (IF), initial soil moisture (ISM), and flow reduction coefficient (Rc) were 20 %, 0.4, 200 mm month-1, and 0.6, respectively. The average monthly discharge during the period of 2008-2017 ranged from 3.16-31.18 m3s-1. The total water needs of 5.041 m3 s-1 per month. The water availability per month was surplus in the rainy season (October-April), but deficit in the dry season (May-September). This research not only contributes to enriching references for similar research in Krueng Aceh Watershed, Indonesia but can also be applied to other watersheds according to the current conditions of watershed characteristics.