Abstract
Study Region: The River Frome, a chalk stream in West Dorset, UK.
Study Focus: High-resolution hydrological models are required to integrate with the current wave of high-frequency data and advance our understanding of pollutant sources, pathways, and sinks. This presents several challenges in chalk streams, as their high-permeability and unique hydrogeological characteristics often leads to complex models that are overparameterized and computationally burdensome. In this article, we develop a novel and parsimonious modelling approach to describe the surface hydrology for a chalk stream in high resolution (15-minute frequency, ≤ 100 m cross-section spacing), using groundwater levels as a proxy for spring discharges.
New Hydrological Insights for the Region: Our results show that chalk stream dry-weather flows can be simulated accurately and parsimoniously at high-resolution (Nash-Sutcliffe efficiency = 0.97, mean relative error = 2.86 %, for a five-year period). We also show that spring discharges are the dominant form of flow accretion in all seasons and are critical to dilute sewage treatment inputs during the ecological growing season, whilst runoff and quick-flow pathways in the river valley corridor contribute a small proportion to annual flow accretion (< 5.2 %). Due to its simplicity and few parameters to calibrate, this modelling approach has broad applicability in lowland permeable catchments. Management implications include expeditious investigations of high-resolution freshwater quality responses to pollution and informing abstraction limits to sustain robust ecological conditions.
Study Focus: High-resolution hydrological models are required to integrate with the current wave of high-frequency data and advance our understanding of pollutant sources, pathways, and sinks. This presents several challenges in chalk streams, as their high-permeability and unique hydrogeological characteristics often leads to complex models that are overparameterized and computationally burdensome. In this article, we develop a novel and parsimonious modelling approach to describe the surface hydrology for a chalk stream in high resolution (15-minute frequency, ≤ 100 m cross-section spacing), using groundwater levels as a proxy for spring discharges.
New Hydrological Insights for the Region: Our results show that chalk stream dry-weather flows can be simulated accurately and parsimoniously at high-resolution (Nash-Sutcliffe efficiency = 0.97, mean relative error = 2.86 %, for a five-year period). We also show that spring discharges are the dominant form of flow accretion in all seasons and are critical to dilute sewage treatment inputs during the ecological growing season, whilst runoff and quick-flow pathways in the river valley corridor contribute a small proportion to annual flow accretion (< 5.2 %). Due to its simplicity and few parameters to calibrate, this modelling approach has broad applicability in lowland permeable catchments. Management implications include expeditious investigations of high-resolution freshwater quality responses to pollution and informing abstraction limits to sustain robust ecological conditions.
Original language | English |
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Article number | 102022 |
Journal | Journal of Hydrology: Regional Studies |
Volume | 56 |
Early online date | 19 Oct 2024 |
DOIs | |
Publication status | E-pub ahead of print - 19 Oct 2024 |
Data Availability Statement
Data supporting this study are openly available from the NERC EDS Environmental Information Centre at https://doi.org/10.5285/0d5c7e45–2c43–4276-af0d-8d941db2e124Acknowledgements
We are grateful to Wessex Water Ltd. for providing effluent flow data from their assets, and to Ian Colley, specifically for his expertise in hydrogeology and useful feedback.We are grateful to DHI for providing a licence to MIKE powered by DHI software products (MIKE Zero software package).
Flow gauging data and groundwater level from observation boreholes were made available by the Environment Agency (EA) under the Open Government Licence v3.0 https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/.
The use of 1 m composite digital terrain model (DTM) 2022 data to derive a DEM of the river valley corridor is acknowledged with the following attribution statement: © Environment Agency copyright and/or database right 2022. All rights reserved.
Keywords
- Chalk stream
- Groundwater level
- High-resolution
- Hydrological model
- Parsimonious
- Proxy
ASJC Scopus subject areas
- Water Science and Technology
- Earth and Planetary Sciences (miscellaneous)