Modelling small groundwater systems: experiences from the Braunton Burrows and Ainsdale coastal dune systems, UK

Abstract

Coastal dunes are delicate systems that are under threat from a variety of human and natural influences. Groundwater modelling can provide a better understanding of how these systems operate and can be a useful tool towards the effective management of a coastal dune system, e.g. by identifying strategically important locations for flora and fauna and guiding the planning of management operations through predicting impacts from climatic change, sea level rise and land use management. Most dune systems are small, typically of the size 10-100 km 2 , compared with inland groundwater systems. Applying conventional groundwater modelling approaches to these small systems presents a number of challenges due to the local scale of the system and the fact that the system boundaries (sea, drains, ponds etc.) are close to the main body of the aquifer. In this paper, two case studies will be presented using different modelling approaches to understand the groundwater balance in two dune systems in the UK. The studies demonstrate that, although conventional hydraulic models can describe the general system behaviour, a fuller understanding of the recharge mechanisms and system boundaries is needed to represent adequately system dynamics of small groundwater systems.

Use of point scale models to improve conceptual understanding in complex aquifers: An example from a sandstone aquifer in the Eden valley, Cumbria, UK

“…This can be achieved with a variety of data analysis approaches. Typically these involve a series of activities: a combination of data gathering and monitoring, the interpretation of these data to develop a conceptual understanding of surface and groundwater flow regimes and the subsequent testing of that understanding using mathematical modelling, for example Abesser et al (2017). The refinement of the conceptual model and its encapsulation in the numerical model is, by its nature iterative and benefits from the use of different data types to develop understanding and to compare model outputs (Schilling et al, 2019).…”

Recruitment of Melaleuca quinquenervia (Myrtaceae) in the fringing forests of the Myall Lakes, NSW, Australia

“…Of note, at Paperbark Picnic Area and One Horse Sands, the foreshore zone is backed by remnant dunes that have a deep sandy profile. Rainfall accumulating in the dune sand would create an underlying, freshwater table in the foreshore zone with a considerable amount of downward pressure towards the lake, as described by Stratford et al (2013) and Abesser et al (2017). Hence, it was often the case that when the lake water was quite saline here, the underlying groundwater, often right up to the water's edge, remained quite fresh.…”

Fine‐scale hydrological niche segregation in coastal dune slacks

“…Ainsdale NNR has an extensive hydrological monitoring network, where the water table depth (WTD) has been measured monthly since 1972 (Clarke & Ayutthaya 2010;Abesser et al, 2017). The names (numbers) used for dune slacks in this study follow the naming convention of the ongoing water table data collection.…”