| Title: | Hydrological modeling of the Upper Indus Basin: A case study from a high-altitude glacierized catchment Hunza |
| Authors: | Garee, K., X. Chen, A. Bao, Y. Wang and F. Meng |
| Year: | 2017 |
| Journal: | Water |
| Volume (Issue): | 9(1) |
| Pages: | |
| Article ID: | 17 |
| DOI: | 10.3390/w9010017 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic only |
| Primary Application Category: | snowmelt, frozen soil and/or glacier melt processes |
| Secondary Application Category: | climate change assessment |
| Watershed Description: | 13,567.25 km^2 Hunza River, located in the Karakoram Mountain Range and in the Upper Indus Basin headwaters region in northeast Pakistan. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | The Soil and Water Assessment Tool (SWAT) model combined with a temperature index
and elevation band algorithm was applied to the Hunza watershed, where snow and glacier-melt are
the major contributor to river flow. This study’s uniqueness is its use of a snow melt algorithm
(temperature index with elevation bands) combined with the SWAT, applied to evaluate the
performance of the SWAT model in the highly snow and glacier covered watershed of the Upper Indus
Basin in response to climate change on future streamflow volume at the outlet of the Hunza watershed,
and its contribution to the Indus River System in both space and time, despite its limitation; it is not
designed to cover the watershed of heterogeneous mountains. The model was calibrated for the years
1998–2004 and validated for the years 2008–2010. The model performance is evaluated using the four
recommended statistical coefficients with uncertainty analysis (p-factor and r-factor). Simulations
generated good calibration and validation results for the daily flow gauge. The model efficiency
was evaluated, and a strong relationship was observed between the simulated and observed flows.
The model results give a coefficient of determination (R2) of 0.82 and a Nash–Sutcliffe Efficiency
index (NS) of 0.80 for the daily flow with values of p-factor (79%) and r-factor (76%). The SWAT
model was also used to evaluate climate change impact on hydrological regimes, the target watershed
with three GCMs (General Circulation Model) of the IPCC fifth report for 2030–2059 and 2070–2099,
using 1980–2010 as the control period. Overall, temperature (1.39 C to 6.58 C) and precipitation
(31%) indicated increased variability at the end of the century with increasing river flow (5%–10%);
in particular, the analysis showed smaller absolute changes in the hydrology of the study area towards
the end of the century. The results revealed that the calibrated model was more sensitive towards
temperature and precipitation, snow-melt parameters and Curve Number (CN2). The SWAT results
also provided reliable information for the daily runoff from the sub-basin watersheds responding
to changing climatic conditions. SWAT can thus be used to devise effective strategies for future
sustainable water management in the region, while combating vulnerabilities against floods and
water storage in downstream water reservoirs such as the Diamer-Basha dam. |
| Language: | English |
| Keywords: | Soil and Water Assessment Tool (SWAT); hydrological modelling; Hunza river;
Upper Indus Basin; snow and glacier-melt |