Uncertainty in annual streamflow and change in reservoir content data from selected surface-water gaging stations on the lower Colorado River

Fact Sheet ◽  
2002 ◽  
Author(s):  
David W. Anning
Keyword(s):  
Surface Water ◽  
Colorado River ◽  
Annual Streamflow ◽  
Lower Colorado River

scholarly journals Winter Inputs Buffer Streamflow Sensitivity to Snowpack Losses in the Salt River Watershed in the Lower Colorado River Basin

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 3
Author(s):  
Marcos D. Robles ◽  
John C. Hammond ◽  
Stephanie K. Kampf ◽  
Joel A. Biederman ◽  
Eleonora M. C. Demaria
Keyword(s):  
River Basin ◽  
Colorado River ◽  
Snow Accumulation ◽  
Colorado River Basin ◽  
Scale Model ◽  
Annual Streamflow ◽  
Basin Scale ◽  
Salt River ◽  
Lower Colorado River Basin ◽  
Lower Colorado River

Recent streamflow declines in the Upper Colorado River Basin raise concerns about the sensitivity of water supply for 40 million people to rising temperatures. Yet, other studies in western US river basins present a paradox: streamflow has not consistently declined with warming and snow loss. A potential explanation for this lack of consistency is warming-induced production of winter runoff when potential evaporative losses are low. This mechanism is more likely in basins at lower elevations or latitudes with relatively warm winter temperatures and intermittent snowpacks. We test whether this accounts for streamflow patterns in nine gaged basins of the Salt River and its tributaries, which is a sub-basin in the Lower Colorado River Basin (LCRB). We develop a basin-scale model that separates snow and rainfall inputs and simulates snow accumulation and melt using temperature, precipitation, and relative humidity. Despite significant warming from 1968–2011 and snow loss in many of the basins, annual and seasonal streamflow did not decline. Between 25% and 50% of annual streamflow is generated in winter (NDJF) when runoff ratios are generally higher and potential evapotranspiration losses are one-third of potential losses in spring (MAMJ). Sub-annual streamflow responses to winter inputs were larger and more efficient than spring and summer responses and their frequencies and magnitudes increased in 1968–2011 compared to 1929–1967. In total, 75% of the largest winter events were associated with atmospheric rivers, which can produce large cool-season streamflow peaks. We conclude that temperature-induced snow loss in this LCRB sub-basin was moderated by enhanced winter hydrological inputs and streamflow production.

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