Baseflow separation combined with stratified sampling serving the accurate estimation of pollutant loads—the example of a small catchment with high anthropogenic pressures
- 1Department of Sanitary and Environmental Engineering, Budapest University of Technology and Economics
Abstract
This study presents a modified baseflow separation framework for stratified pollutant load estimation in managed catchments subject to substantial point-source wastewater discharge, applied to the Koppány stream (Hungary), a system characterized by intensive agricultural and wastewater-derived pollution. Three established baseflow separation methods were evaluated, namely the Lyne–Hollick, Eckhardt, and Rimmer–Hartmann approaches. Where the standard Rimmer–Hartmann method yielded physically unrealistic results, a modified three-component formulation was developed by incorporating wastewater as an explicit end-member in the electrical conductivity (EC)-based mixing equation. The modified method produced baseflow-index (BFI) values of 0.80 at Törökkoppány and 0.83 at Tamási, consistent with the Eckhardt filter result of 0.80 at both stations. Event classification thresholds of 0.77 and 0.82 were selected through a sensitivity analysis across nine candidate values per station, yielding non-event volume fractions of 75% and 76%, respectively—in close agreement with the long-term regional BFI of 0.72–0.75 reported for the catchment. Annual loads of metals, nutrients, pharmaceuticals, and per- and polyfluoroalkyl substances were partitioned between event and non-event conditions using a stratified sampling design combining weekly grab samples, event-based automatic sampling, and continuous monitoring of discharge and EC. Load estimates carry inherent uncertainty arising from the binary classification of event and non-event periods and from the assumption of constant wastewater EC and discharge during calibration. The modified framework offers a practical and transferable tool for catchments where point-source discharges substantially alter the natural flow regime.
Related
- Comparison of machine learning and spatial interpolation methods for hourly rainfall data imputation in the Oliwski Stream catchment
- The effects of climatic changes on plant physiological and catchment ecohydrological processes in the high-rainfall catchments of the Murray-Darling Basin: A scoping study
- Long-term observatory of groundwater, soil moisture and rainfall in a French urban catchment
- Environmentally Relevant Concentrations of Nanomaterials Drive Photochemical Production of Reactive Species and Pollutant Degradation in Surface Waters
- Enhancing pollutant removal from contaminated soils using yield stress fluids as selective blocking agents
BibTeX
@article{lajko2026baseflow,
title = {{Baseflow separation combined with stratified sampling serving the accurate estimation of pollutant loads—the example of a small catchment with high anthropogenic pressures}},
author = {Tímea Lajkó and Adrienne Clement and Máté Krisztián Kardos},
journal = {Applied Water Science},
year = {2026},
month = oct,
doi = {10.1007/s13201-026-02986-9},
url = {https://doi.org/10.1007/s13201-026-02986-9},
note = {CC BY},
}
RIS
TY - JOUR
TI - Baseflow separation combined with stratified sampling serving the accurate estimation of pollutant loads—the example of a small catchment with high anthropogenic pressures
AU - Tímea Lajkó
AU - Adrienne Clement
AU - Máté Krisztián Kardos
PY - 2026
DA - 2026/10/25
JO - Applied Water Science
DO - 10.1007/s13201-026-02986-9
UR - https://doi.org/10.1007/s13201-026-02986-9
AB - This study presents a modified baseflow separation framework for stratified pollutant load estimation in managed catchments subject to substantial point-source wastewater discharge, applied to the Koppány stream (Hungary), a system characterized by intensive agricultural and wastewater-derived pollution. Three established baseflow separation methods were evaluated, namely the Lyne–Hollick, Eckhardt, and Rimmer–Hartmann approaches. Where the standard Rimmer–Hartmann method yielded physically unrealistic results, a modified three-component formulation was developed by incorporating wastewater as an explicit end-member in the electrical conductivity (EC)-based mixing equation. The modified method produced baseflow-index (BFI) values of 0.80 at Törökkoppány and 0.83 at Tamási, consistent with the Eckhardt filter result of 0.80 at both stations. Event classification thresholds of 0.77 and 0.82 were selected through a sensitivity analysis across nine candidate values per station, yielding non-event volume fractions of 75% and 76%, respectively—in close agreement with the long-term regional BFI of 0.72–0.75 reported for the catchment. Annual loads of metals, nutrients, pharmaceuticals, and per- and polyfluoroalkyl substances were partitioned between event and non-event conditions using a stratified sampling design combining weekly grab samples, event-based automatic sampling, and continuous monitoring of discharge and EC. Load estimates carry inherent uncertainty arising from the binary classification of event and non-event periods and from the assumption of constant wastewater EC and discharge during calibration. The modified framework offers a practical and transferable tool for catchments where point-source discharges substantially alter the natural flow regime.
SN - 2190-5487
SN - 2190-5495
ER -