Integrated Environmental Modeling applied at the basin scale: linking different types of models using the OpenMI standard to improve simulation of groundwater processes in the Thames Basin, UK.

The Thames Basin in the south-east of England consists of multiple and separate aquifer systems, which are used for public and private water supply and also provide baseflow to the River Thames and its tributaries. The most important aquifer is the Chalk, a pure white fractured limestone, which has been extensively studied over the past decades to understand its hydraulic characteristics. A distributed numerical model can be built, therefore, to simulate the groundwater flows within this aquifer. Groundwater processes in other aquifer systems such as the Jurassic limestone (Great and Inferior Oolite Groups) in the north-west of the basin are complex and less well understood. These aquifers also support river baseflow under drought conditions. This paper presents the results of using the Open Modeling Interface (OpenMI) standard to allow appropriate models to be linked. The composition consists of a fully distributed groundwater flow model of the Chalk, a simplified groundwater model of the Jurassic limestones and a river model. OpenMI allows the different types of models to communicate during run-time. This approach allows an appropriate representation of the flow processes within the Thames basin and consequently improves the simulation of groundwater flows, enabling better management of groundwater and surface water resources under future climate scenarios.