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Old water contribution to streamflow: Insight from a linear Boussinesq model
Author(s) -
Fiori A.
Publication year - 2012
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2011wr011606
Subject(s) - streamflow , precipitation , aquifer , groundwater , hydrology (agriculture) , environmental science , dimensionless quantity , geology , meteorology , geography , mechanics , drainage basin , physics , geotechnical engineering , cartography
Old water contribution to streamflow is studied by the means of a simple groundwater model. The principal aim is not to develop a tool for applications but rather to understand some of the dynamics of old and new water after a rainfall event by using a simple model with a minimum set of variables. Event water is traced by solute transport analysis. Adopting a simple rainfall pulse of finite duration, the method identifies two key dimensionless parameters ruling the old water contribution to streamflow: a dimensionless rainfall time δ , ratio between the rain duration and the characteristic response time of the aquifer, and the ratio ρ between rainfall volume and the water volume present in the aquifer at the beginning of rainfall. It was found that the ρ parameter is crucial in the old water contribution to a rainfall event; less so are the temporal dynamics of rainfall, expressed through δ . For typical values of ρ it is expected that old water contributes more than 50% of the total streamflow. These findings suggest that the groundwater dynamics may have a strong influence on the way that the hillslope responds to the rainfall input, and hence the partition between new (precipitation) and old (pre‐event) waters.