The aim of this contract is to ensure that the Environment Agency’s Cotswolds Groundwater model period is extended and refined to improve the model’s calibration, allowing a more accurate representation of the current state of the Cotswolds aquifer. This numerical MODFLOW-96 model covers the complex geology and hydrogeology of the Cotswolds Oolitic limestones. The model is regularly used for the strategic assessment of available water resources and making water abstraction licensing decisions in the Cotswolds. To keep the model up to date and fit for purpose, both in terms of capturing recent climatic conditions and local abstraction licence changes, the model requires updating. From using the model since it was delivered in 2013, some model refinement has been identified in order to improve its calibration.