Underground Connection (IMAGE) University of Freiburg Caption Blue circles indicate that the effective catchment area is larger than the topographic catchment area, while red circles illustrate the opposite. The dark blue and dark red circles indicate large deviations. Credit Credit: Andreas Hartmann Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.