ABSTRACT
The use of hydrological catchments as a basis for environmental research is related to their functional role in integrating chemical, biological and physical processes. This chapter focuses on the issues of using such lumped data in the modelling of catchments. It presents an analysis of the consistency and reliability of catchment delimitation based upon topographic maps of different scale for selected catchments. The catchments are used as areal units for which the average annual volume of rainfall are estimated by intersecting the rainfall and catchment datasets and calculating the product of the proportion of each cell within a catchment and the rainfall levels. As the soils in a catchment have a major impact on both river flows and stream chemistry, a hydrological model, HOST, has been used to apportion incoming precipitation to surface runoff and to infiltration.
