ABSTRACT
This chapter focuses on processes transforming precipitation over the catchment into stream runoff-usually called runoff processes. From measurements of precipitation and estimates of stream runoff, he showed that the volume of precipitation over the Seine River catchment was more than enough to feed the river with water. For any point along a water course, and for any other point in the landscape, a catchment can be defined. It is the area within which all water flowing through the point as surface runoff or groundwater flow has been collected from precipitation. Precipitation falling within a catchment boundary can be stored in the catchment temporarily, return to the atmosphere as evapotranspiration or be transported out of the catchment as stream or groundwater runoff.
