Umar (2025) Climate change adjustment factor on rainfall depths in river basins of Khyber Pakhtunkhwa, Pakistan

Identification

• Journal: Climatic Change
• Year: 2025
• Date: 2025-10-28
• Authors: Muhammad Umar
• DOI: 10.1007/s10584-025-04041-z

Research Groups

• Water & Agriculture Division, National Engineering Services Pakistan (Pvt.) Limited (NESPAK), Lahore, Pakistan
• Centre of Excellence in Water Resources Engineering (CEWRE), University of Engineering and Technology (UET), Lahore, Pakistan

Short Summary

This study assesses the impact of climate change on future intense rainfall events in the river basins of Khyber Pakhtunkhwa, Pakistan, to inform flood management and infrastructure planning. It projects an increase in design rainfall adjustment factors ranging from 1.0% to 24.3% for a 100-year return period under various climate change scenarios.

Objective

• To assess the influence of future intense rainfall events to enhance the incorporation of climate change in the planning of flood management and infrastructure development in Khyber Pakhtunkhwa, Pakistan.

Study Configuration

• Spatial Scale: Seven major river basins in Khyber Pakhtunkhwa province, Pakistan: Swat, Panjkora, Chitral, Kabul, Kurrum, Gomal, and DI Khan.
• Temporal Scale:
  • Baseline period: 1985–2014 (30 years)
  • Future projection period: 2025–2099

Methodology and Data

• Models used:
  • 20 Coupled Model Intercomparison Project Phase 6 (CMIP-6) General Circulation Models (GCMs), shortlisted to 5 representative GCMs per basin.
  • Statistical downscaling technique: Quantile Delta Mapping (QDM) for bias correction.
  • Frequency analysis: Generalized Extreme Value (GEV) distribution.
  • Software: R-programming language (downscaleR package), HEC-SSP.
• Data sources:
  • Observed daily rainfall data from Kalam, Dir, Chitral, Kabul, Bannu, Zhob, and DI Khan weather stations (1985–2014).
  • CMIP-6 GCM data downloaded from the Copernicus Climate Change Service, utilizing Shared Socioeconomic Pathways (SSP) 2–4.5 and SSP 5–8.5 scenarios.
  • Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) for catchment area estimation.

Main Results

• Climate change adjustment factors for design rainfall under a 100-year return period in Khyber Pakhtunkhwa, Pakistan, are projected to range from 1.0% to 24.3%.
• For the SSP 2–4.5 scenario (100-year return period), projected increases in 1-day maximum rainfall are: Swat (3.10%), Panjkora (0.80%), Chitral (0.80%), Kabul (2.5%), Kurrum (5.0%), Gomal (13.8%), and DI Khan (3.3%).
• For the SSP 5–8.5 scenario (100-year return period), projected increases in 1-day maximum rainfall are: Swat (12.1%), Panjkora (12.0%), Chitral (10.8%), Kabul (12.3%), Kurrum (16.3%), Gomal (24.3%), and DI Khan (15.6%).
• Overall, daily maximum rainfall is projected to increase by 0.7% to 13.8% for return periods of 2.33 to 100 years under SSP 2–4.5, and by 2.9% to 24.3% under SSP 5–8.5.
• The study identified CMCC-CM2-SR5, NorESM2-MM, CESM2, EC-Earth3-Veg-LR, and BCC-CSM2-MR as the five most frequently shortlisted GCMs across the river basins.

Contributions

• Provides specific, regionally tailored climate change adjustment factors for design rainfall in the river basins of Khyber Pakhtunkhwa, Pakistan, which are crucial for flood management and infrastructure development.
• Offers a robust methodology for selecting representative GCMs and applying bias correction (QDM) and frequency analysis (GEV) to project extreme rainfall events under CMIP-6 scenarios.
• Highlights the importance of considering local variations and characteristics of river basins, suggesting that a general Clausius-Clapeyron scaling factor of 7% may not be universally applicable.
• Serves as a valuable reference point for engineers, planners, and future climate change investigations in the region, aiding in the development of effective adaptation strategies.

Funding

No funding involved.

Citation

@article{Umar2025Climate,
  author = {Umar, Muhammad},
  title = {Climate change adjustment factor on rainfall depths in river basins of Khyber Pakhtunkhwa, Pakistan},
  journal = {Climatic Change},
  year = {2025},
  doi = {10.1007/s10584-025-04041-z},
  url = {https://doi.org/10.1007/s10584-025-04041-z}
}