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A stochastic approach to the evaluation of residence times
Author(s) -
Maran Stefano
Publication year - 2002
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 - 10.1029/2001wr000975
Subject(s) - residence time (fluid dynamics) , inflow , outflow , autocorrelation , stochastic differential equation , stochastic process , stochastic modelling , constant (computer programming) , residence , mathematics , environmental science , statistics , hydrology (agriculture) , mechanics , geology , physics , geotechnical engineering , meteorology , computer science , demography , sociology , programming language
Residence times of conservative pollutants in a lake or a reservoir are studied without the usual approximation of constant inflow/outflow. The effects of a random discharge flushing out a reservoir are investigated with the techniques of stochastic differential equations. Stochastic properties of the concentration in the reservoir are derived from stochastic properties of discharge (moments, autocorrelation function, and probability distribution function), and some approximations are analyzed. The major results are two simple and usable corrections for the residence time in two limiting cases: when autocorrelation time of discharge is much shorter than reservoir residence time and, at the opposite, when it is much longer.