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Multi-scale analysis of the fluxes between terrestrial water storage, groundwater, and stream discharge in the Columbia River Basin
Citation:
Sproles, E., S. Leibowitz, P. Wigington, S. Patil, J. Reager, AND J. Famiglietti. Multi-scale analysis of the fluxes between terrestrial water storage, groundwater, and stream discharge in the Columbia River Basin. Presented at American Geophysical Union, San Francisco, CA, December 09 - 13, 2013.
Impact/Purpose:
Snow that accumulates during the wet winters of the Columbia River Basin (CRB) melt in the spring to recharge aquifers and fill streams. These streams and aquifers provide critical water resources during the summer, when demand is at its peak. Because the supply and demand of water in the CRB are seasonally misaligned, it is critical to understand the storage and fluxes of water in the region. Our research provides a clarified understanding of the regional fluxes of terrestrial water storage (TWS) and its transition to streamflow in the Snake River (182,000 km¬¬2), Upper Columbia (155,000 km¬¬2), and the greater CRB (614,000 km¬¬2). These three watersheds represent distinct climatic and geologic provinces found in the region. Our findings show regional-scale loops of the hydrologic cycle that are characteristic of each basin. These loops quantify the timing and influence of snowmelt to aquifer recharge, and show how this transition is expressed in streamflow. This more nuanced understanding of the fluxes of water across and through the landscape can help identify scarcity and surplus with regards to time and space. In turn, this knowledge can help develop adaptive use and management strategies to deal with potential scarcity in present and projected climates. An improved systematic understanding of the interconnections between TWS and streamflow help provide a better foundation for quantifying and understanding the impacts of projected climates on water surplus and scarcity.
Description:
The temporal relationships between the measurements of terrestrial water storage (TWS), groundwater, and stream discharge were analyzed at three different scales in the Columbia River Basin (CRB) for water years 2004 - 2012. Our nested watershed approach examined the Snake River (182,000 km¬¬2), Upper Columbia (155,000 km¬¬2), and the greater CRB (614,000 km¬¬2). These three watersheds represent distinct climatic and geologic provinces found in the region. TWS (the vertically-integrated sum of snow, soil moisture, surface water, and groundwater) was measured remotely by NASA’s Gravity Recovery and Climate Experiment (GRACE). Results show that over the course of a water year, TWS and discharge exhibit a characteristic counter clockwise hysteresis pattern for each of the three regional watersheds. Similarly, in each of the three watersheds groundwater and discharge also exhibit a characteristic hysteresis pattern over the course of a water year—only in a clockwise direction. Our findings provide regional characteristics that quantify and describe the fluxes between snow, groundwater, and discharge, and also identify the out-of-phase relationship between the region’s wet winters and groundwater recharge from during the spring. The methods and results presented in this study provide an analytic framework to incorporate remotely-sensed measurements of TWS to better understand how regional watersheds function as an integrated system, and also to identify potential water surplus and scarcity in the CRB and other regional watersheds.