Temporal and spatial scale of response area and groundwater variation in Till

The main objective of this study has been to test the theories describing the pathways and the processes generating runoff from rainfall. A small forest catchment in south‐eastern Norway has been used as a research area. The results of this study agree with previous work (Myrabø, 1986), suggesting that the response area concept gives a good description of the behaviour of the processes in small catchments in moraine terrain in Norway. Maps of the areal distribution of groundwater levels at different stream discharges are used, derived from measurements at more than 100 observational sites. The saturated area and response area in the catchment are controlled by the position of the groundwater level. The variations of the measured groundwater level, obtained automatically each hour, and at various stream discharges, are therefore thoroughly investigated. Correlation analysis and comparisons of discharge–groundwater level relationships, show distinct hysteresis effects. Threshold groundwater levels that indicate the limit for quick runoff from particular parts of the catchment have been identified. The behaviour of the discharge–groundwater relationship is dependent on location, antecedent conditions and size of response area before each precipitation event. © 1997 John Wiley & Sons, Ltd.