Stable water isotopes in precipitation and rivers (18O and 2H) have been frequently used as environmental tracers to understand processes and timescales in precipitation-runoff transformations. It has become increasingly apparent, that long-term data sets are required to fully understand such runoff processes in terms of regional climate variability and climate change. Stable isotopes of water are an ideal tracer to not only investigate changes in water flow but also in transport. In Germany, we have one of the world’s densest national networks for long-term isotopic analysis in precipitation and rivers. The latter covers monthly isotopic composition at 9 locations of the last 10-25 years. These data will be used to identify the average as well as the temporal evolution of isotopic composition in German rivers and how it is related to meteorological, geographical and hydrological parameters.

The objective of the thesis is (1) to identify the national distribution of average water isotopes in German rivers, (2) to compare average ratios in rivers to average ratios in precipitation considering difference in the climatic and geographic conditions in the catchments, (3) to investigate the variability of isotopic composition in rivers and its influencing factors (climate, precipitation, runoff) over time and (4) how it is related to long-term changes in isotopic composition in precipitation.

The work will include the analysis of long-term data of monthly stable isotopic composition in German rivers (25 a: Rhine, Mosel; 10 a: Danube, Neckar, Main, Ems, Weser, Elbe, Oder). Changes in the long-term data sets will be compared to long-term changes in isotopic composition in precipitation, discharge, and climate. Regional differences and similarities will be identified.

Christine Stumpp

The master student’s office is in Munich (Helmholtz Zentrum München, Institute of Groundwater Ecology).

Christine Stumpp christine.stumpp@helmholtz-muenchen.de Tel. +49 89 3187 4165

long-term dataset analysis, isotope hydrology, P-Q relationship, global change

English

- Dutton, A., Wilkinson, B.H., Welker, J.M., Bowen, G.J. and Lohmann, K.C., 2005. Spatial distribution and seasonal variation in O-18/O-16 of modern precipitation and river water across the conterminous USA. Hydrol. Process., 19: 4121-4146 - Rozanski, K., Araguás-Araguás, L. and Gonfiantini, R., 1992. Relation between long-term trends of oxygen-18 isotope composition of precipitation and climate. Science, 258: 981-985 - Stumpp, C., Klaus, J., and Stichler, W.,. Long-term data set analysis of stable isotopic composition in German precipitation. In review .