SUPERVISOR: Christine STUMPP 

PROJECT ASSIGNED TO: Hatice TÜRK 

Runoff generation by rainfall is a fundamental catchment process that provides details of the impact and risk associated with water resource management in a river basin. However, quantitatively estimating rainfall-runoff relations particularly in complex and heterogeneous catchments is a challenging task.The proposed research aims at a better characterization of the influence of hydrometeorological variables on runoff generation and catchment-wide water flow. The main focus is on using naturally reoccurring patterns in hydrological flux and state variables as repeated tests. To achieve this, hydrologically similar water transit time measures which are the transit time distribution (TTD), and the fraction of young water (Fyw) will be defined. While TTD represents the diverse set of flow paths of precipitation through a catchment and their associated velocities, Fyw is a strong indicator of the proportion of stream flow that is younger than approximately three months. Those two variables are essential catchment features that give information about storage, flow paths, and water sources of a catchment. Along these lines, the objectives of this research are:

• To define TTD and Fyw similarity.

• To investigate hydrological conditions that lead to similar water transit times and explain the similarities/differences using hydrometeorological variables

• To investigate water transit times for hydrologically similar conditions and explain the similarities/differences with hydrometeorological variables

The conceptual DYNAMIT modeling framework Hrachowitz et al. (2013)and statistical analysis will be used to test the effect of synthetic TTDs on the isotope response in runoff, and the sine wave method Kirchner (2016) will be used with synthetic data to define similar Fyw. Finally, the results will be used to search hydrologically similar TTD and Fyw in real-world data and compare their respective hydrometeorological variables. The present project contributes to the ”Connectivity” research cluster as it investigates hydrological processes related to solute transport and transformation, as well as the ”Vulnerability” research cluster, as the quantity and quality of freshwater are affected by transit times.

Bibliography

Hrachowitz Markus, Savenije H, Bogaard TA, Tetzlaff D, Soulsby C. What can flux tracking teach us about water age distribution patterns and their temporal dynamics? // Hydrology and Earth System Sciences. 2013. 17, 2. 533–564.

Kirchner James W. Aggregation in environmental systems–Part 1: Seasonal tracer cycles quantify young water fractions, but not mean transit times, in spatially heterogeneous catchments // Hydrology and Earth System Sciences. 2016. 20, 1. 279–297.