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 km2, 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.
Highlights
Dune system hydrologyDunes are an important feature of the British coastline
The aim of this paper is to demonstrate how differing approaches to developing groundwater models can lead to a) better understanding and improved conceptual models of the groundwater systems, b) identifying the key drivers that affect water table levels and changes such as recharge and boundary conditions, c) the suitability of existing data to validate and test the conceptual models, including identification of additional data requirements and d) being able to simulate adequately seasonal, inter annual and longer term trends in groundwater levels
We have described two independent approaches for modelling dune groundwater systems, (1) a three-dimensional, numerical groundwater flow model (ZOOMQ3D) with spatially distributed parameters for dune system properties and (2) a one-dimensional single-point / lumped parameter model, to simulate groundwater flow in small sand dunes systems at Braunton Burrows and Ainsdale, respectively
Summary
Dunes are an important feature of the British coastline. In England and Wales, they often form shallow rain-fed aquifers draining to the periphery of the dune system; to the fore dunes and the beach and inland to low-lying land (Fig. 1). An important aspect of groundwater data collection and monitoring is to understand and quantify the different components of the hydrological water balance (Fig. 1) This includes understanding the temporal and spatial distribution of groundwater heads (such as water table and pond levels), flow directions, rainfall recharge inputs as well as aquifer discharge, i.e. inland seepage or groundwater flow towards the sea. The aim of this paper is to demonstrate how differing approaches to developing groundwater models can lead to a) better understanding and improved conceptual models of the groundwater systems, b) identifying the key drivers that affect water table levels and changes such as recharge and boundary conditions, c) the suitability of existing data to validate and test the conceptual models, including identification of additional data requirements and d) being able to simulate adequately seasonal, inter annual and longer term trends in groundwater levels. (1) Grid construction and initial parameterisation (2) Sensitivity analysis (3) Dynamic balance simulation (4) Model calibration
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
