Hydrologic Response to Changes in the Timing and Rate of Snowmelt: Implications for Water Resource Management in the Western U.S.
Abstract
Regional warming over the Western U.S. has profoundly impacted land surface hydrology by decreasing the proportion of snowfall versus rainfall and by shifting the timing of snowmelt earlier in spring. Remote sensing of the mountain snowpack has transformed our ability to understand the hydrologic sensitivity to this regional warming. In this regard, improved characterization of snowmelt through remote sensing and modeling has led to important new findings, notably: i) that earlier snowmelt associated with warming leads to slower snowmelt; and ii) that slower snowmelt decreases runoff generation due to decreases in subsurface flow. In this presentation, example studies from local to regional scales will be used to illustrate the novelty and robustness of these findings. Examples from headwater alpine systems using high resolution remotely sensed data and distributed snowmelt models indicate that the timing of snowmelt explains 40 - 60% of the interannual variability in snowmelt rate. Analyses of SNOTEL data at the regional scale corroborate this signal with a 10 day shift in the timing of snowmelt resulting in an approximately 7 mm change in snowmelt rate. Finally, regional-scale analysis of runoff and baseflow estimates from the Variable Infiltration Capacity model indicate that baseflow and runoff are strongly controlled by snowmelt rate (R2 = 0.73 and 0.42 for baseflow and runoff as dependent variables, respectively). As regional warming may continue to decrease the magnitude of snow accumulation and shift the timing of snowmelt earlier in spring, further decreases in snowmelt rate and associated decreases in proportional runoff production should be expected. The implications of these changes in snowmelt partitioning are far-reaching in the context of the mountain water balance, ecosystem function, and water resource management. Application of these findings toward improved water resource management at annual to decadal time scales will be discussed via example stakeholder co-production studies in California, Colorado, and Wyoming.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.U42A..06M
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 1833 Hydroclimatology;
- HYDROLOGYDE: 1880 Water management;
- HYDROLOGYDE: 6309 Decision making under uncertainty;
- POLICY SCIENCES