The requirements of the Land-Ocean Interaction Study (LOIS) to model a
large number of river systems are considered and an approach outlined
that is compatible with data availability and LOIS objectives. The fu
nctionality of software to assist data preparation and model applicati
on is discussed and compared with the existing QUASAR model. The under
lying rationale behind the development of a new software suite, QUESTO
R, is described. As an example, the application of QUESTOR to the mode
lling of the River Wharfe is presented. This includes the method used
to define the extent of the network to be modelled and the ways in whi
ch tributaries, industrial discharges and abstractions were to be repr
esented. Model calibration procedures are discussed and model validati
on results presented. (C) 1998 Elsevier Science B.V.