2015, a Year without Snow in the Oregon Cascades: Recession Response of Small Watersheds
Abstract
In the Oregon Cascades, the winter snow conditions in 2015 were equivalent to 4 degree Celsius climate warming scenario, representing a unique opportunity to test fundamental hypotheses of headwater streams response to changes in the amount and timing of recharge. The Cascade Mountain range is characterized in two groups: 1) the Western Cascades are old volcanic flows with well-defined drainage basins and high snowmelt runoff, and 2) the High Cascades are younger volcanic flows where precipitation infiltrates into deep aquifer system. Each system responds differently to yearly precipitation patterns. With the Oregon Cascade Mountain range receiving less than 20% of their average snowfall in the winter of 2015, we seek to describe the hydrological responses of such anomalous - but near future normal - recharge conditions. A total of six small watersheds were investigated. Continuous stage measurements were combined with discrete streamflow discharge measurements to create discharge rating curves and a continuous hydrographs. While summer stream did meet or drop below historic records, they did not go as low as predicted by established models, revealing some specific hydrological properties of the aquifers that sustains the river flow in such recharge conditions. Watersheds that were predominantly surface fed has stream flows an order of magnitude lower than previous years, while the spring fed stream in new volcanic systems have only slightly lower stream flows compared to last year. Recession analysis of stream flows (Brutsaert and Niebert 1977) were used to quantify the hydraulic properties of the aquifers and draw hypothesis regarding regional responses of river flows to low snow recharge processes. Surface fed streams exhibited overall late time recession behavior while feeling the effects of aquifer boundary conditions and spring fed systems exhibited early time recession behaviors without feeling the effects of aquifer boundary conditions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.H43E1499J
- Keywords:
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- 1807 Climate impacts;
- HYDROLOGYDE: 1829 Groundwater hydrology;
- HYDROLOGYDE: 1831 Groundwater quality;
- HYDROLOGYDE: 1866 Soil moisture;
- HYDROLOGY