Client: Environment Agency
Services: Groundwater Modelling
Issues: Management of groundwater abstraction within Merseyside
Summary: Historic over-abstraction of the Permo-Triassic Sandstone aquifers beneath Merseyside resulted in falling groundwater levels and upflow of saline water from depth and intrusion from the Mersey Estuary. A groundwater model was developed by ESI to significantly improve the technical basis of groundwater abstraction licensing decisions in the study area.
The Permo-Triassic Sandstones of the Liverpool and Ormskirk and Lower Mersey Basin aquifer units are a significant groundwater resource for both industrial and public water supply. Intensive abstraction of groundwater started in the 19th Century and over-abstraction in some parts of the aquifer has resulted in falling groundwater levels and the upflow of saline water from depth and intrusion from the adjacent Mersey Estuary.
In 2004, the Environment Agency commissioned ESI to carry out a scoping study to identify the key issues in the area and to develop an appropriate approach to tackle them.
ESI was then appointed to carry out the main study, working with BV under the NEECA contract. The overall objective of the project was to carry out a phased water resource assessment to deliver a significantly improved technical basis for groundwater abstraction licensing decisions in the study area.
In Phase 1 of the project, ESI reviewed the data for the study area and developed an improved conceptual model. A regional groundwater model was then constructed to implement this understanding of the aquifer. The process of model refinement led to further improvements in understanding, particularly regarding the role of faults in compartmentalising the aquifer. The model is now being used as a water management tool to assist the Environment Agency and United Utilities to determine the most appropriate way of managing the groundwater abstractions in the area.