Analyzing the Spatiotemporal Variability of Precipitation Over Khyber Pakhtunkhwa in Changing Climate

Abstract

This study investigates the spatiotemporal variability of precipitation in Khyber Pakhtunkhwa (KPK), Pakistan, from 1981 to 2024 using Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) data. The Mann–Kendall test, Sen’s slope estimator, and precipitation indices, Precipitation Concentration Index (PCI), Extreme Precipitation Index (EPI), Consecutive Wet Days (CWD), and Consecutive Dry Days (CDD) were applied to assess trends and extremes. The province has a complex topography and transitional subtropical climate, which makes it highly susceptible to precipitation variability affecting water resources, agriculture, and disaster risk management. Results reveal a statistically significant (p < 0.05) increasing trend in annual precipitation across most of Upper and Middle KPK, with Sen’s slope values ranging between +0.28 and +0.67 mm/year, while a decreasing trend (–0.15 to –0.42 mm/year) was observed in Lower KPK. PCI values varied between 12% and 24%, indicating moderate to strong irregularity, with the highest concentration observed in the southern districts. EPI analysis showed an increase of 12–18% in extreme rainfall events (>25 mm/day) in Middle KPK, confirming intensification of shortduration heavy precipitation. The CWD index revealed prolonged wet spells (>30 days) in northern districts (Swat, Shangla, Mansehra), whereas CDD values exceeded 100–120 days in southern districts (D.I. Khan, Bannu, Karak), suggesting increasing drought recurrence. Future ensemble projections (2025–2055) indicate a 7–14% rise in monsoon rainfall in Upper and Middle KPK and a 10–20% reduction in precipitation in southern areas, implying growing hydro-climatic disparities. Overall, precipitation in KPK is becoming increasingly erratic and spatially polarized, highlighting the urgent need for region-specific adaptation, flood control in the north, drought-resilient agriculture in the south, and integrated water resource management in the central districts.