1. Dep. of Environ. Science and Eng.Faculty of Eng., Hiroshima Univ.Higashi‐Hiroshima724Japan
2. Environ. Eng. Lab., Dep. of Civil Eng., Univ. of AalborgSohngaardsholmsvej 57DK‐9000AalborgDenmark
3. Dep. of LandAir, and Water Resour., Univ. of CaliforniaDavisCA95616