Climate-driven disturbances in the San Juan River sub-basin of the Colorado River
Accelerated climate change and associated forest disturbances in the southwestern USA are anticipated to have substantial impacts on regional water resources. Few studies have quantified the impact of both climate change and land cover disturbances on water balances on the basin scale, and none...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-01-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/22/709/2018/hess-22-709-2018.pdf |
| Summary: | Accelerated climate change and associated forest disturbances in the
southwestern USA are anticipated to have substantial impacts on regional
water resources. Few studies have quantified the impact of both climate
change and land cover disturbances on water balances on the basin scale, and
none on the regional scale. In this work, we evaluate the impacts of forest
disturbances and climate change on a headwater basin to the Colorado River,
the San Juan River watershed, using a robustly calibrated (Nash–Sutcliffe efficiency
0.76) hydrologic model run with updated formulations that improve estimates
of evapotranspiration for semi-arid regions. Our results show that future
disturbances will have a substantial impact on streamflow with implications
for water resource management. Our findings are in contradiction with
conventional thinking that forest disturbances reduce evapotranspiration and increase
streamflow. In this study, annual average regional streamflow under the
coupled climate–disturbance scenarios is at least 6–11 % lower than
those scenarios accounting for climate change alone; for forested zones
of the San Juan River basin, streamflow is 15–21 % lower. The monthly
signals of altered streamflow point to an emergent streamflow pattern related
to changes in forests of the disturbed systems. Exacerbated reductions of
mean and low flows under disturbance scenarios indicate a high risk of low
water availability for forested headwater systems of the Colorado River
basin. These findings also indicate that explicit representation of land
cover disturbances is required in modeling efforts that consider the impact
of climate change on water resources. |
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| ISSN: | 1027-5606 1607-7938 |