Leveraging Stable Water Isotopes to Characterize Precipitation and Streamflow Generation in a Headwater Watershed System
Abstract
Understanding the current climate's governing mechanisms for a snow dominant catchment in the Pacific Northwest (PNW) may provide clues for what is to come for the South Fork Palouse (SFP) watershed as climate changes. The SFP is a headwater system relevant to ecosystem health downstream. Previous studies on SFP hydrology focused on the understanding of regional hydrology and baseflow generation processes. We will use stable water isotopes to characterize short term governing processes for precipitation and understand how water is stored and released during large precipitation events. The equilibrium and kinetic fractionation of stable water isotopes are primarily dependent on temperature and the source of water vapor for the PNW. The change in stable isotope composition along air mass paths from the ocean and overland reflect complex hydrologic and atmospheric processes. A recent study in the SFP found that seasonal influences dominated isotopic signals in precipitation whereas surface waters were relatively stable throughout the year. We will characterize water vapor sources, storm tracks and diagnose short term governing processes for both rain and snow. As large precipitation events occur, some fraction of pre-event water is released to runoff as infiltration occurs and hydraulic gradients change. This process varies considerably based on surface and soil structure as well as precipitation type and snowmelt intensity. Our data set includes pre-event, event and post-event isotopic compositions, which allows for separating storm runoff contribution of pre-event and event water at the field scale. Using these data in concert with hydrometric data, we will reflect on conceptual models for streamflow generation to determine dominant runoff mechanisms.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMH127...09M
- Keywords:
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- 1630 Impacts of global change;
- GLOBAL CHANGE;
- 1807 Climate impacts;
- HYDROLOGY;
- 1863 Snow and ice;
- HYDROLOGY;
- 1879 Watershed;
- HYDROLOGY