The use of GIS (geographical information systems) in hydrology and wat
er management has its roots in ideas about the relationship between cl
imate, catchment, channel and society that emerged more than a hundred
years ago. From these beginnings, hydrological GIS has come to be def
ined primarily by modelling in the science domain and by asset (notabl
y infrastructure) management in the water and river management domain.
In both contexts it can be demonstrated that data quality represents
the ultimate constraint, but that the quest for higher resolution may
carry with it some significant problems. These constraints are develop
ed through an examination of the potential use of high resolution spat
ial data in flood insurance applications of GIS. While the issues rais
ed have clear technical implications, they also have important profess
ional and ethical ramifications which are worthy of consideration as a
backdrop to the current and future status of GIS in hydrology and wat
er management. (C) 1998 John Wiley & Sons, Ltd.