Title: Integrating land surface and groundwater models to assess the impacts of land use change on the British water cycle
Lead Supervisor: Dr Marco Bianchi, British Geological Survey
Email: marcob@bgs.ac.uk
Co-supervisors: Prof. Anne Verhoef, Department of Geography and Environmental Science, University of Reading
UKRI funding only covers Home fees which increase annually. International students may still apply to this project, but will be required to meet the difference between the International and Home student fees themselves.
The water cycle is controlled by a combination of atmospheric, surface, and subsurface processes. To understand the impacts of climate and other human induced changes on the hydrological system and to design effective water resources management strategies, it is essential to adopt a multidisciplinary integrated approach that accounts for these interactions. Land use changes have significant effects on the water cycle by altering evapotranspiration, infiltration, and runoff processes [e.g. 1,2]. These in turn affect groundwater recharge, storage, and river-aquifer interactions.
Although robust predictions of these impacts at regional and national scales are critical for sustainable land use planning and water resource management, developing modelling tools that capture the complex interplay between vegetation, climate, and surface/subsurface water systems remains a major challenge. Most available models focus on simulating only certain components or present oversimplifications of certain processes.
The recently developed British Groundwater (BGWM) is a national-scale, high resolution (1 km), numerical model of groundwater flow dynamic across the British mainland capturing complex groundwater processes including river/aquifer interactions, abstractions, and lateral groundwater flows [3]. However, the representation of groundwater recharge in BGWM does not account for dynamic land – atmosphere feedbacks or the influence of vegetation on the water balance fluxes. By contrast, land surface models (LSM) such as the Community Land Model (CLM) or the Joint UK Land Environment Simulator (JULES) can simulate land-atmosphere interactions in detail, including energy and water fluxes, vegetation dynamics, and soil processes. Yet, LSMs typically include a simplified representation of groundwater dynamics and are unable to fully resolve lateral subsurface flows and storage for closing the water budget in catchments and estimating the buffering effect of groundwater during hydrological extremes.
The complementary strengths and weakness of BGWM and LSMs present an opportunity to develop an integrated model of Britain’s water cycle. This PhD project aims to couple BGWM and land surface models to build a physically based, national-scale modelling framework to simulate both vegetation-driven processes and detailed groundwater dynamics. The coupled model will be applied to investigate how land use changes (e.g., arable to urban; grass to woodland) and related vegetation species choice (e.g., needleleaf versus broadleaf trees; temperate versus ‘warm-climate’ crops or pasture species) will influence groundwater recharge, river baseflows, and water availability under current and future climates. During the PhD, expected scenarios of land-use change in the UK in response to socio-economic pressures (housing, infrastructure, food, energy) and climate mitigation and adaptation strategies [4] will be developed using national-scale datasets and policy targets. These scenarios will be considered by coupled model simulations as well as both present-day and future climate conditions (e.g. UKCP18 climate projections). Present and historical conditions will be simulated to test the coupled model outputs against multiple datasets including groundwater level, river flow, and evapotranspiration data. Uncertainty and sensitivity analysis will be performed to understanding how different land use transitions affect spatial and temporal patterns of recharge at the national scale and to what extent they impact groundwater resilience under natural and anthropogenic stress.
By quantifying the influence of land use change on the British water cycle, the project will provide evidence to inform policy decisions, climate adaptation, and water resource management. The project will also contribute to some critical open questions in integrated hydrological modelling including coupling strategies, spatial and temporal scaling issues, highly parameterised calibration approaches, uncertainty and model performance evaluation, and computational efficiency.
Training opportunities:
The student will join the BGS Environmental Modelling group of Bianchi and Department of Geography and Environmental Science research group of Verhoef. They will work closely with experts in groundwater, land surface modelling, hydrometeorology, and land use/climate change impacts. They will receive training in soil- and groundwater physics theory, groundwater modelling (MODFLOW-6), land surface modelling (JULES or equivalent), and integrated hydrological modelling. Additional skills in high-performance computing, uncertainty quantification, model calibration and evaluation, and geospatial data analysis will be developed. The student will acquire advanced interdisciplinary and computational expertise, preparing them for careers in academia, applied research, and environmental policy.
Student profile:
This project would be suitable for students with a strong academic background in Earth and Environmental Sciences, Hydrology, Environmental Engineering, Physical Geography, Physics, or a closely related discipline. A solid foundation in hydrogeological, hydrological or environmental modelling is desirable, alongside an interest in understanding interactions between climate, land use, vegetation and groundwater systems. UKRI funding only covers Home fees which increase annually. International students may still apply to this project, but will be required to meet the difference between the International and Home student fees themselves.
References:
• Bianchi, M., et al. (2024). Simulation of national-scale groundwater dynamics in geologically complex aquifer systems: An example from Great Britain. Hydrological Sciences Journal, 69(5), 572–591. https://doi.org/10.1080/02626667.2024.2320847
• Buechel, K., et al. (2022). Hydrological impact of widespread afforestation in Great Britain using a large ensemble of modelled scenarios. Communications Earth & Environment, 3(10), 6. https://doi.org/10.1038/s43247-021-00334-0
• Collins, S., et al. (2023). Modelling the effectiveness of land-based natural flood management in a large, permeable catchment. Journal of Flood Risk Management, 16(2), e12896. https://doi.org/10.1111/jfr3.12896
• UK Parliament. (2023). The land use in England: meeting net zero goals—Report. Retrieved from https://publications.parliament.uk/pa/ld5803/ldselect/ldland/105/10502.htm
