MEFC — A future pan-European Minimum residual flow
assessment tool
The Minimum Ecological Flow Calculator (MEFC) is an interactive tool developed in cooperation between the Czech University of Life Sciences in Prague and the T.G. Masaryk Water Research Institute to evaluate and
compare different approaches to calculate Minimum Residual Flow (MRF) or Minimum Ecological Flow (MEF) and to provide additional flow data analysis for the end user. The Danube River Basin (DRB) was chosen to evaluate different approaches to calculating MEF because it is the most international river basin in Europe. There are several methods of calculating the MRF or MEF (essence is the same) throughout European states due to different climatological or hydrological conditions. Several states (such as the Czech Republic) are developing new methodologies
either to comply with legislation or to improve their environmental standards [1]. A document issued by the European Commission summarises the current progress within the EU and, in accordance with the Water Framework Directive, defines the guidelines for the development of new methodologies [2]. The latest version of MEFC is available on the website https://shiny.vuv.cz/mefc/.
MEF calculation
The current version of calculation is based on the methodology developed by Petr Balvín et al. [1]. This new methodology replaces the old one from year 1979, where minimum residual flows were derived from actual values of Q97. The final version of MEFC is still under development. The main issue is to collect information about methodologies from all countries participating in this project. The purpose is to allow the end user to choose the state methodology to calculate the MEF and display the actual value in the actual plot shown. In other words, the user can switch between different approaches within the same visualised observed data and vice versa.
Data analysis
The MEFC application provides several analyses of available data from gauging stations located throughout the Danube basin.
The Time series section provides a visualisation of the streamflow during the selected period. The values are not only visualised by a line graph, but also differentiated on a colour scale. Additional functions can display other useful changes such as the logarithmic axis or critical quantiles, which are crucial for the calculation of the MEF (Figure 1) or point measurements. These functions make it easier for the end user to work with selected data and calculated values of the MEF. Another feature for the analysis of
calculated MEF data is the calculation of the total deficit volume from a given time range, which could be useful for water management authorities or water abstraction applicants or interested layman. Total deficit volume would be calculated based on values of MEF or on the critical quantiles.
The Seasonal section (figure 2) shows the seasonal decomposition of the discharge by month and its maximum values. Seasonal decomposition of discharge is visualised in the selected period (coloured part) and also over the whole available period (white part). This could be useful in developing methodologies for calculating MEF that are split due to seasonal conditions. A similar visualisation is provided by the Parde coefficient, which shows the percentage of total annual runoff in each month. This section is still under development (current version is avaliable in the app).
Flow duration curves show the cumulative frequency, which is the percentage of time that specified discharges have been equalled or exceeded during a given period. Related to the flow duration curve is a section called M-day discharge (figure 3) which compares the selected duration curve with the WMO reference datasets. There are two WMO 20 year reference periods within the MEFC — the first starting in 1980 and the second in 1990.
Each section will have an optional output in the form of a short plot summary as text and a summary of the theory associated with each plot or statistical method. Last but not least, information about gauging station and its basin will also be part of optional text output. The references section briefly summarises the different methodologies of the participating countries.
Acknowledgements
The Minimum Ecological Flow Calculator is being developed within the framework of the Danube River Lighthouse Action (DALIA), an international project that gathers multidisciplinary information in the field of Danube River Basin Management in order to solve complex environmental problems related to river basins. There are 22 organisations such as universities, authorities or research institutes etc. from all over Europe participating in this project. The DALIA project is part of the EU mission “Restore our oceans and waters by 2030”.
This text was originally published as a poster at the Kostelecke Inspirovani 2023 conference and then transferred to this Medium story with the kind permission of all the authors.
Bibliography
[1] Vizina, Adam & Balvin, Pavel & Hanel, Martin & Moravec, Vojtech & Nesladkova, Magdalena & Blocher, Johanna. (2021). Minimum Residual Flows for Catchments in the Czech Republic. Water. 13. 10.3390/w13050689.
[2] European Commission. Directorate-General for the Environment. 2016. Ecological flows in the implementation of the Water Framework Directive guidance document n 31. Publications Office.
