Publication Date:
2014-03-26
Description:
Warming will affect snowline elevation, potentially altering the timing and magnitude of streamflow from mountain landscapes. Presently, the assessment of potential elevation-dependent responses is difficult because many gauged watersheds integrate drainage areas that are both snow- and rain-dominated. To predict the impact of snowline rise on streamflow, we mapped the current snowline (1980 m) for the Salmon River watershed (Idaho, USA) and projected its elevation after 3 °C warming (2440 m). This increase results in a 40% reduction in snow-covered area during winter months. We bolster this analysis by collecting streamflow records from a new, elevation-stratified gauging network of watersheds contained within high (2250 – 3800 m), mid (1500 – 2250 m) and low (300 – 1500 m) elevations that isolate snow, mixed, and rain-dominated precipitation regimes. Results indicate that lags between percentiles of precipitation and streamflow are much shorter in low elevations and that their annual percentiles (Q 25 & Q 75 ) of streamflow occur 30 – 50 days earlier than in mid- and high-elevation watersheds. Extreme events in low elevations are dominated by low- and no-flow events whereas mid- and high-elevations experience large magnitude floods. Only mid- and high-elevation watersheds are strongly cross-correlated with catchment-wide flow of the Salmon River, suggesting that changes in contributions from low-elevation catchments may be poorly represented using mainstem gauges. As snowline rises, mid-elevation watersheds will likely exhibit behaviors currently observed only at lower elevations. Streamflow monitoring networks designed for operational decision making or change detection may require modification to capture elevation-dependent responses of streamflow to warming. This article is protected by copyright. All rights reserved.
Print ISSN:
0885-6087
Electronic ISSN:
1099-1085
Topics:
Architecture, Civil Engineering, Surveying
,
Geography
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