Splicing recharge and groundwater flow models in the Environment Agency National Groundwater Modelling System

Abstract

AbstractThis paper explains the background and development of the Environment Agency National Groundwater Modelling System (NGMS) to integrate recharge functionality with the existing groundwater modelling (Modflow functionality).The Environment Agency groundwater models were originally developed primarily as a tool for making high-level strategic decisions but their use for short-term extreme event scenarios, such as drought or flood, has been relatively limited. This functionality has been constrained by the format of the rainfall/recharge input datasets. Undertaking scenario runs based on change in climate and weather has only been possible by direct manual alteration of those input datasets, which is not always practical on a day-to-day basis.Full implementation of recharge models into NGMS changes this, allowing the recharge models to be run in the NGMS environment and output to be generated. The fusion aspect of the process involves that output being processed in such a way that it can be used by NGMS as input into a Modflow scenario run. This process is explained using the example of a recent drought scenario in the Wessex Basin groundwater model.