Topic 5: Water transit time distributions as indicators for the vulnerability of riverine ecosystems under different pressures from social metabolism

Introduction/background

Rivers receive water from different flow paths and sources with a wide range of transit times, particular during extreme events. Solutes that impair river water quality are transported along the different flow paths. How transit times change over time and how this influences the chemical and biological status of river systems is not well known but it would offer the possibility of using transit time information for assessing the vulnerability of rivers.

Main objective

The goal of this PhD project is to use transit times of water as an indicator of riverine ecosystems’ vulnerability to pollutants. Therefore, the objectives are to calculate time-variable transit time distributions, to investigate how transit time distributions are affected by extreme events, and how this affects river water quality considering social metabolism as a factor for different pollutants and their sources. The results will be used to define water transit time indices that can be used for assessing the river’s ecosystem vulnerability to different pressures from social metabolism.

Approach

Stable and radioactive water isotope time series from large river basins will be used with hydrological modelling to estimate water transit times. Transit times from different river basins will be compared, and changes under extreme conditions will be related to flow conditions. Statistical methods will be used to compare transit times with river water quality data. River basins will be divided into threat classes by analysing the agricultural intensification and urbanization within the Industrialized Riverine Landscapes. Different transit time based indices will be developed to relate information on water flow paths to the water quality status of rivers.