Submitted on: 22 February 2002.
Revised on: 12 April 2002.
Accepted on: 09 June 2002.
___________________Journal of Hydrology---ELSEVIER
Submitted on: 15 February 2012.
Revised on: 19 May 2012.
Accepted on: 13 June 2012.
___________________Journal of Hydrology---ELSEVIER
http://reply.papertrans.cn/2/173/17286/17286-33.png
http://reply.papertrans.cn/2/173/17286/17286-34.png
http://reply.papertrans.cn/2/173/17286/17286-35.png
http://reply.papertrans.cn/2/173/17286/17286-36.png