ESI was commissioned by the Environment Agency to develop a numerical model of the East Yorkshire Chalk aquifer. The model was used for managing water resources in the area, particularly for WFD and CAMS purposes.
The East Yorkshire Chalk forms an important aquifer for the supply of groundwater for public water supply for Yorkshire Water. Discharge from the Chalk comprises the primary source of baseflow to local watercourses, particularly the Gypsey Race and the River Hull. Baseflow is also critical for the maintenance of some groundwater dependent ecosystems. However, peak winter groundwater flows can also exacerbate flooding in downstream areas such as Hull.
ESI was commissioned by the Environment Agency to develop a numerical model of the East Yorkshire Chalk aquifer which would help them to manage water resources, balancing the pressure of water demand and maintaining baseflow to groundwater dependant watercourses.
The project consisted of two separate phases, firstly to undertake a conceptual study of the aquifer, and subsequently to develop a numerical groundwater model.
The Conceptual Model
Initially all the relevant literature and hydrological/hydrogeological data was collated and reviewed. A detailed analysis of the groundwater system, including groundwater level behaviour, river-aquifer interactions and an assessment of recharge processes was performed, culminating in the calculation of a quantitative aquifer-scale water balance.
ESI prepared a detailed report presenting the conceptual model as a basis to inform the construction of the numerical groundwater model.
A regional, transient recharge and groundwater model running from 1970 to 2007 was developed and calibrated against groundwater levels and stream flows. This was initially used to aid the CAMS appraisal for the aquifer.
The model was configured to be compatible for uploading into the National Groundwater Modelling System. This enabled the Environment Agency to examine the impact of proposed abstraction applications/variations on the groundwater system.
ESI also developed a series of future climate scenarios. These examined the impact of potential changes in recharge on the aquifer, reviewing the implications for water resources and flows in groundwater dependant surface waters. Results of the climate scenarios will help the Environment Agency strategy for the future management of water resources across the aquifer.
Model output was also used for the River Hull flood model, providing baseflow inputs for a range of groundwater level return periods for the Chalk groundwater fed tributaries of the Hull.