Assessment of Hydrological Drought in Anthropocene: A Case of Reservoir’s Effect in Arid Region

Drought is a critical natural hazard that can cause severe environmental and social economic damages special in arid region like Pothohar region of Pakistan. Analysis of observation data is useful in progressing this knowledge as these human activities and feedback are intrinsically included. Hence, in current study, the impact of Simly dam on Hydrological drought characteristic at downstream has been analyzed. Two drought analysis methods i.e., 50th and 80th percentiles (TL-50 and TL-80) threshold level method and standardized index approach were used for hydrological drought calculation and upstream-downstream approach was used for assessment of impact of Simly dam. For upstream-downstream approach the entire data period was divided into two sub periods i.e. pre dam (1970-1982) and post dam (1983-2012). Based on the analysis, it was concluded that during post-dam period there was a decrease in total duration by 1.88%, frequency by 15.24% and maximum severity by 69.5% of drought events occurred at downstream as compared to upstream. The Simly dam reservoir may have mitigated the short-term drought at downstream, however, unable to reduce the impact of long-term drought. Moreover, in the presence of dam a delay in drought occurrence was observed at downstream. This study also showed an applicable way forward with quantifying the human influence on hydrologic drought.