Contact

Postal
Address:
Institute of Environmental Physics
Im Neuenheimer Feld 229
Heidelberg University
D-69120 Heidelberg
Room: 202
Phone: (+49) 6221 54-6379
E-Mail: Lukas.Riedel@iup.uni-heidelberg.de
ORCID ID: 0000-0002-4667-3652
LinkedIn: https://linkedin.com/in/lukas-riedel/
GitHub: https://github.com/peanutfun

Current Research

As postdoctoral researcher at the STRUCTURES Cluster of Excellence of Heidelberg University I research computational methods for modeling cell elasticity in the research project CP3: "From Molecules to Cells and Tissue".

PhD Project

During my PhD i focused on computational methods for modeling and simulating environmental systems.

Soil Hydrology and Data Assimilation

Classical environmental physics focuses on hydrology and fluid dynamics. The partial differential equations describing these dynamics are typically solved computationally by using finite element methods. I follow this route of computational science in soil hydrology, where soil water flow is described by the Richards equation. Although these dynamics have been established for several decades, the highly non-linear soil hydraulic properties pose a severe challenge to numerical models and require advanced, modern methods for retrieving accurate solutions. As a maintainer of DORiE, a software package for solving the Richards equation and the passive transport equation with discontinuous Galerkin methods, I strive to make accurate, high-order numerical methods available to soil physicists without a strong background in numerics.

Given the correct parameters and boundary conditions, simulations can produce precise forecasts for limited time periods. But in soil hydrology, boundary conditions, system states, and hydraulic properties are difficult to observe. To improve the accuracy of predictions, we work on combining observations and simulation results through data assimilation methods. In a recent, synthetic study, we investigate the effects of small-scale soil heterogeneity which is not resolved by local measurements on the predictive capabilities of an estimated soil profile, using DORiE and an ensemble Kalman filter.

Retrieve the digital version of my doctoral thesis from the University Library of Heidelberg University: https://doi.org/10.11588/heidok.00029401.

Complex and Evolving Environmental Systems

We observe that many, if not all, environmental systems are strongly interconnected and comprise agents and entities operating on very different spatial and temporal scales. The study of these complex, adaptive systems is both conceptually and operationally challenging. The non-linear, sometimes even irregular interactions can rarely be formulated in classical physical equations. Observations of entire ecosystems with the required precision are equally out of our reach.

Research on complex and evolving environmental systems therefore relies on heuristic computer models and mostly qualitative statements and predictions. This requires an agile development of vastly different computer models. Among the most established methods for investigating these systems are cellular automata, agent-based models, and network models. Our software project Utopia is the effort to join these disparate model types, exploit their similarities, and create a development environment for complex and evolving environmental systems, with a focus on computational performance, high flexibility in model development, and a collaborative workflow.

Find more information on Utopia on our official website: https://utopia-project.org/.

Software Projects

Teaching

Publications

Peer Reviewed Publications:

  • Lukas Riedel, Benjamin Herdeanu, Harald Mack, Yunus Sevinchan, and Julian Weninger. 2020. “Utopia: A Comprehensive and Collaborative Modeling Framework for Complex and Evolving Systems.” Journal of Open Source Software 5 (53): 2165. https://doi.org/10.21105/joss.02165.
  • Lukas Riedel, Santiago Ospina De Los Ríos, Dion Häfner, and Ole Klein. 2020. “DORiE: A Discontinuous Galerkin Solver for Soil Water Flow and Passive Solute Transport Based on DUNE.” Journal of Open Source Software 5 (52): 2313. https://doi.org/10.21105/joss.02313.
  • Hannes H. Bauser, Lukas Riedel, Daniel Berg, Peter A. Troch, and Kurt Roth. 2020. “Challenges with Effective Representations of Heterogeneity in Soil Hydrology Based on Local Water Content Measurements.” Vadose Zone Journal 19 (1): e20040. https://doi.org/10.1002/vzj2.20040.

Doctoral Thesis:

Conferece and Workshop Contributions

Peer Reviewed Conference Papers:

  • Yunus Sevinchan, Benjamin Herdeanu, Harald Mack, Lukas Riedel, and Kurt Roth. 2020. “Boosting Group-Level Synergies by Using a Shared Modeling Framework.” In Computational Science – ICCS 2020, edited by Valeria V. Krzhizhanovskaya, et al., 12143:442–456. Lecture Notes in Computer Science. Cham, Switzerland: Springer International Publishing. https://doi.org/10.1007/978-3-030-50436-6_32.

Conference Presentations:

Seminar Contributions: