STAGE: STAtistical modelling of Groundwater Extremes

Dr Ben Marchant1, Dr John Bloomfield1,  Dr Emma Eastoe2, Dr Jennifer Wadsworth2

1The British Geological Survey, Lancaster University 

The primary aim of the STAGE project is to establish a sustainable collaborative relationship between earth scientists at the British Geological Survey (BGS) and extreme value statisticians at Lancaster University.  To this end, the participants are exploring how extreme value methodologies can quantify risk and give insight into earth science systems that are subject to extreme events such as earthquakes, landslides, space weather, groundwater droughts and floods and sink holes. The project is centred on a case study exploring the drivers of extreme groundwater levels.

Researchers from BGS and Lancaster have met twice to discuss potential collaborations. These discussions have led to three proposals for potential MSc projects which will be offered to Lancaster students later in the year. The proposals are concerned with (i) the occurrence of extreme space weather events that have to potential to disrupt terrestrial communication and navigation systems (ii) a multi-scale analysis of the relationships between rainfall, river levels and groundwater levels and (iii) the potential to sequester carbon in the soil. A PhD proposal regarding the use of machine learning methodologies in soil mapping is also being formulated. Preparations are in hand for the end-of-project workshop where the Lancaster statisticians will meet with a wider group of BGS scientists to discuss the capabilities of extreme value methodologies and additional opportunities for future research.

With regards to the case study, the Lancaster researchers have completed initial analysis of the longest records of groundwater levels held by BGS. They have fitted models to the tails of the marginal distributions that describe relationships with various explanatory variables, and explored the strength and nature of the temporal dependence between measurements in the upper and lower tails. Now, both parties will explore what insights these models offer regarding the risk of groundwater droughts and floods, how the severity of these events has changed over time and the potential for further changes of severity in a changing climate.

Final Report and talk given at SECURE Annual Conference 2016 can be viewed below: