Dosa


Die Bodenkultur - Journal for Land Management, Food and Environment

M. Dóša, L. Holko and Z. Kostka:

Estimation of the mean transit times using isotopes and hydrograph recessions

Summary

We have calculated mean transit times (MTT) of streamflow in three mountain catchments of different orders (areas 22, 45 and 1095 km², respectively) by means of isotopic method (δ18O) and by the method based on hydrograph recession during the warm period of the year. Data from years 2005–2008 were used in calculations. MTTs calculated by isotopes (the sine-curve approach) varied between 13–19 months. Seeming correlation of MTT with catchment area reflects rather differences in runoff formation at different scales. Hydrograph recession provided two typical recessions. MTTs calulcated from the shorter hydrograph recessions for the two larger catchments were comparable with those given by δ18O. Longer runoff data series are necessary in applying the hydrograph recession method due to the relatively small number of uninterrupted recessions in individual years.

Key words: Mean transit time, isotopes, hydrograph recession, topography.