ABSTRACT:

This dataset is a by-product of my doctoral research on the hydrological impacts of climate change in the Upper Indus Basin (UIB).

The data provided here covers the full extent of UIB and is provided as bias-corrected and downscaled versions of 5 RCM-GCM experiments (by CORDEX-SA). The "Precipitation" (PCP), and "Temperature" (TMP) projections are in the shape of “point data” for 173 sub-basin centroids, in a ready-to-use format for input to SWAT hydrological model. Additionally, data (with future dates) for other required parameters by the Hydrological Model “SWAT”, such as "Humidity" (RHU), "Solar-radiation" (SLR), and "wind" (WND) is also provided.

It includes bias-corrected and downscaled projections from selected General Circulation Models (GCMs) under the RCP 4.5 and RCP 8.5 scenarios. The selection process involved evaluating GCMs based on mean and extreme changes, as well as their ability to reproduce past climate. To account for uncertainties in high mountainous regions like the UIB, a wide range of future GCM climate projections, including wet-warm, wet-cold, dry-warm, and dry-cold scenarios, were considered. The final selection of GCMs was based on a weighted score assigned to each criterion.

It was found that the Coordinated Regional Downscaling Experiment (CORDEX) already had RCM data for our “top-ranked” GCMs, therefore Dynamically downscaled climate projections from five CORDEX-SA experiments *(IPSL-CM5A-MR_RCA4, MPI-ESM-LR_RCA4, NorESM1-M_RCA4, Can ESM2_RegCM4-4, and GFDL-ESM2M_RCA4)* were downloaded and further statistically downscaled (bias-corrected) over the UIB. These experiments used two different Regional Climate Models (RCMs), RCA4 and RegCM4, resulting in finer-scale outputs (0.44°) than the source GCMs.

The downscaled projections for the year 2100 indicate temperature increases ranging from 2.3°C to 9.0°C and precipitation changes ranging from a slight annual increase of 2.2% under drier scenarios to a high increase of 15.9% in wet scenarios. In all scenarios, future precipitation is expected to be more extreme, with a decrease in the probability of wet days and an increase in precipitation intensities. Spatially, there is a distinct precipitation decrease over the southeastern parts of the basin and an increase in the northeastern parts, particularly pronounced in "Dry-Warm" and "Median" scenarios over the late 21st century.

Full details of the study can be found at:

Khan, A.J.; Koch, M. Selecting and Downscaling a Set of Climate Models for Projecting Climatic Change for Impact Assessment in the Upper Indus Basin (UIB). Climate 2018, 6, 89. https://doi.org/10.3390/cli6040089

ABSTRACT:

This dataset stems from my PhD research on climate change hydrological impacts in the Upper Indus Basin (UIB). The available hydro-meteorological data for UIB, typical of challenging mountainous terrains, suffer from coverage and quality issues, especially at higher altitudes where weather stations are scarce. Consequently, the existing data fail to capture winter precipitation at higher altitudes and temperature variations in elevated areas.
To address these limitations, the provided data was generated and used as input for the SWAT hydrological model. This adjusted dataset, suitable for direct input to SWAT or similar models, was interpolated to sub-basin centroids (173 sub-basins). It includes "precipitation," "Temperature," "Humidity," "Solar-radiation," and "wind."
The methodology used for data generation is detailed in two publications:
• Khan, A.J.; Koch, M. "Correction and Informed Regionalization of Precipitation Data in a High Mountainous Region (Upper Indus Basin) and Its Effect on SWAT-Modelled Discharge," Water 2018, 10, 1557. https://doi.org/10.3390/w10111557
• Khan, A.J.; Koch, M. "Generation of a long-term daily gridded precipitation dataset for the Upper Indus Basin (UIB) through temporal Reconstruction, Correction & Informed Regionalization-‘ReCIR’," International Soil and Water Conservation Research, Volume 9, Issue 3, 2021, Pages 445-460, ISSN 2095-6339, https://doi.org/10.1016/j.iswcr.2021.01.005.
In summary, this study aimed to create a realistic daily gridded precipitation dataset (1961–2010) for UIB, incorporating orographic adjustments. The procedure involved temporal reconstruction of precipitation series, regionalization, and adjustments for orographic effects and glacier storage changes. The resulting dataset was validated through SWAT-modelled streamflow responses, demonstrating consistency with observed flows across the UIB. The spatial distribution pattern of the reconstructed (1961–1996) and reference (1997–2008) precipitation also aligns with the atmospheric circulation pattern in the region.