1. UK Centre for Ecology & Hydrology (UKCEH), Wallingford, Oxfordshire OX10 8BB, U.K.
2. Lancaster Environment Centre (LEC), Lancaster University, Lancaster LA1 4YQ, U.K.
3. National Oceanography Centre, European Way, Southampton SO14 3ZH, U.K.
4. Department of Civil Engineering, Aalborg University, Thomas Manns Vej 23, Aalborg 9220, Denmark