Integrating lysimeter drainage and eddy covariance flux measurements in a groundwater recharge model.

Field-scale water balance is difficult to characterize because controls exerted by soils and vegetation are mostly inferred from local-scale measurements with relatively small support volumes. Eddy covariance flux and lysimeters have been used to infer and evaluate field-scale water balances because they have larger footprint areas than local soil moisture measurements. This study quantifies heterogeneity of soil deep drainage (D) in four 12.5-m2repacked lysimeters, compares evapotranspiration from eddy covariance (ETEC) and mass balance residuals of lysimeters (ETwbLys), and modelsDto estimate groundwater recharge. Variation in measuredDwas attributed to redirection of snowmelt infiltration and differences in lysimeter hydraulic properties caused by surface soil treatment. During the growing seasons of 2010, 2011 and 2012, ETwbLys(278, 289 and 269 mm, respectively) was in good agreement with ETEC(298, 301 and 335 mm). Annual recharge estimated from modelledDwas 486, 624 and 613 mm for three calendar years 2010, 2011 and 2012, respectively. In summary, lysimeterDand ETECcan be integrated to estimate and model groundwater recharge.Editor D. Koutsoyiannis [ABSTRACT FROM AUTHOR]