In connection with environmental impact assessments for the purpose of landuse planning, investigations on the hydrological site conditions and their possibe changes are of vital importance for einvironmental decision-making. In many cases long-term measurements must be carried out on various water balance components and parameters of hydrological processes, including substance deposition caused by air pollution. Such monitoring must take into account the large spatial and temporal variation and correlation of measured quantities (see Brechtel, 1989).
Dat from a forest-ecological investigation in the Rhine-Main Valley are used to demonstrate how patterns in field measurements over space and time can be analysed statistically. From a great number of methods used, two that proved useful for several major problems are chosen and explained: repeated measures analysis and time series models with interventions and input variables.