Research Information System
Theoretical and Applied Climatology, vol.156, no.11, 2025 (SCI-Expanded)
Due to a changing climate, the impacts of nonstationarity on drought assessment are becoming critical, yet have not been studied in Pakistan. To address this critical research gap, the study quantifies the effects of nonstationarity on drought assessment in Pakistan. It evaluates stationary and time-nonstationary reconnaissance drought index (RDI) for two distinct periods (1951–1986 and 1986–2021) using gamma distribution, which was a better fit than the log-normal distribution. The drought and wet classifications analysis reveals a significant reversal effect of nonstationarity between period-1 and period-2. Under nonstationarity, drought conditions were increased in the northern high mountains, sub-mountainous, and agricultural plain areas of Pakistan, with the impact reaching up to + 4.05% for extreme, + 5.95% for severe, and + 7.62% for moderate droughts, respectively, during the second period. Conversely, the wet conditions are decreasing in these regions, with the negative impact values of -2.38% for extreme, -5.48% for severe, and − 10.00% for moderate wet classification. However, the western mountainous and coastal regions of Pakistan experience a decrease in the nonstationarity magnitude impact of droughts during period-2, reaching up to -7.14% for extreme, -11.43% for severe, and − 9.29% for moderate droughts, while the wet conditions are increasing in these areas, with the impact reaching up to + 0.48%, + 8.33%, and + 11.90% for extreme, severe, and moderate wet classification, respectively. The nonstationary impacts are amplified during the dry months. The study suggests that accounting for nonstationarity is crucial for improved drought assessments, as it reveals significant zonal and temporal shifts in drought and wet conditions.