Author(s): D. M. C. S. Mimrose; L. N. N. Jayasuriya; M. A. Bhuiyan; M. A. Bari
Linked Author(s):
Keywords: Hydrological drought; Threshold level; Standardized hydrological drought index
Abstract: Drought indices based on meteorological and hydrological properties and the associated threshold level method are popular for assessing and forecasting drought events. When the drought index is below a pre-defined threshold level, the study area is considered to be in drought condition. Translating the drought index level to a streamflow or rainfall value is a more quantifiable expression of drought. In this study, the streamflow based Standardized Hydrological Drought Index (SHDI) was used to identify hydrological drought hazards in Victoria, Australia. The 12 month cumulative streamflow level was defined as the threshold value which was identified using the cumulative distribution function, translating the gamma distributed SHDI values to the cumulative streamflow level. The aim of this study is to examine the sensitivity of the length of the time series data to streamflow threshold. The use of the full set of time series data, when compared to a minimum of 30years of data was shown to vary the cumulative 12 month streamflow by more than 100%, consequently affecting the identification of drought onset, termination, duration and severity. Therefore, the selection of time period should be carefully carried out depending on the specific objectives of the study. Further, study confirms that the streamflow threshold levels are site specific and depends on long term climatic and catchment characteristics.
Year: 2016