Submitted on: 15 August 2008.
Revised on: 16 November 2008.
Accepted on: 05 December 2008.
___________________Journal of Hydrology---ELSEVIER
Submitted on: 07 July 2002.
Revised on: 20 September 2002.
Accepted on: 27 October 2002.
___________________Journal of Hydrology---ELSEVIER
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