Watershed memory at the Coweeta Hydrologic Laboratory: The effect of past precipitation and storage on hydrologic response

The rainfall‐runoff response of watersheds is affected by the legacy of past hydroclimatic conditions. We examined how variability in precipitation affected streamflow using 21 years of daily streamflow and precipitation data from five watersheds at the Coweeta Hydrologic Laboratory in southwestern...

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Bibliographic Details
Published in:Water resources research 2016-03, Vol.52 (3), p.1673-1695
Main Authors: Nippgen, Fabian, McGlynn, Brian L., Emanuel, Ryan E., Vose, James M.
Format: Article
Language:English
Subjects:
Annual
Annual precipitation
Annual runoff
Atmospheric precipitations
Brackish
Correlation
Coweeta
Daily
Dormancy
Evapotranspiration
Hydrologic data
Hydrology
Laboratories
Monthly
Nonlinearity
Precipitation
Precipitation and runoff
Precipitation data
Precipitation estimation
Rain
Rainfall
Rainfall-runoff relationships
Ratios
Regression
Runoff
Seasons
Soil
Soils
Storage
Stream discharge
Stream flow
Time
Variability
Vegetation
water balance
watershed
watershed memory
Watersheds
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Summary:The rainfall‐runoff response of watersheds is affected by the legacy of past hydroclimatic conditions. We examined how variability in precipitation affected streamflow using 21 years of daily streamflow and precipitation data from five watersheds at the Coweeta Hydrologic Laboratory in southwestern North Carolina, USA. The gauged watersheds contained both coniferous and deciduous vegetation, dominant north and south aspects, and differing precipitation magnitudes. Lag‐correlations between precipitation and runoff ratios across a range of temporal resolutions indicated strong influence of past precipitation (i.e., watershed memory). At all time‐scales, runoff ratios strongly depended on the precipitation of previous time steps. At monthly time scales, the influence of past precipitation was detectable for up to 7 months. At seasonal time scales, the previous season had a greater effect on a season's runoff ratio than the same season's precipitation. At annual time scales, the previous year was equally important for a year's runoff ratio than the same year's precipitation. Estimated watershed storage through time and specifically the previous year's storage state was strongly correlated with the residuals of a regression between annual precipitation and annual runoff, partially explaining observed variability in annual runoff in watersheds with deep soils. This effect was less pronounced in the steepest watershed that also contained shallow soils. We suggest that the location of a watershed on a nonlinear watershed‐scale storage‐release curve can explain differences in runoff during growing and dormant season between watersheds with different annual evapotranspiration. Key Points: Watershed memory effects quantifiable at varying time scales Variability in annual runoff largely explained by previous year's storage state Storage‐release curve explains differences in Q for watersheds with different ET
ISSN:0043-1397
1944-7973
DOI:10.1002/2015WR018196