TEMPORAL AND SPATIAL SCALE OF RESPONSE AREA AND GROUNDWATER VARIATIONIN TILL

The main objective of this study has been to test the theories describ ing the pathways and the processes generating runoff from rainfall. A small forest catchment in south-eastern Norway has been used as a rese arch area. The results of this study agree with previous work (Myrabo, 1986), suggesting that the response area concept gives a good descrip tion of the behaviour of the processes in small catchments in moraine terrain in Norway. Maps of the areal distribution of groundwater level s at different stream discharges are used, derived from measurements a t more than 100 observational sites. The saturated area and response a rea in the catchment are controlled by the position of the groundwater level. The variations of the measured groundwater level, obtained aut omatically each hour, and at various stream discharges, are therefore thoroughly investigated. Correlation analysis and comparisons of disch arge-groundwater level relationships, show distinct hysteresis effects . Threshold groundwater levels that indicate the limit for quick runof f from particular parts of the catchment have been identified. The beh aviour of the discharge-groundwater relationship is dependent on locat ion, antecedent conditions and size of response area before each preci pitation event. (C) 1997 John Wiley & Sons, Ltd.