Numerical comparison of streamflow drought index (SDI) and standardized streamflow index (SSI) for evaluation of Isfahan drought status

Abstract

ABSTRACTHydrological droughts are the most serious and alarming variation of droughts due to their numerous long-term negative impacts on natural ecosystems, agricultural capacities, and the water regime of a specific region. Isfahan province, in Iran, is highly prone to this type of drought, and its arid climate has already made the efficient water management in this area a challenging task. Due to the lack of a uniform method for drought evaluation, various indices have been suggested by different researchers over the last few decades. The streamflow drought index (SDI) and standardized streamflow index (SSI) are the two primary hydrological drought indices that have been used in many regions with similar climatic conditions to Isfahan province. Their reliability in previous case studies and the easy computational process have made them suitable drought measurement tools for Isfahan. In this study, these two indices are calculated based on the obtained data from 10 hydrometric stations in Isfahan, for the timeframe (1988–2018). The analysis of SSI and SDI in this region shows consistent and station-specific drought patterns, with moderate drought conditions prevailing. These findings offer valuable insights for regional water resource management and climate adaptation, guiding policies to mitigate the impact of droughts.

Keywords

• Streamflow drought index
• standardized streamflow index
• Pearson probability distribution type III
• hydrometric stations
• Isfahan province