Evaluation of a socio-hydrological water resource model for drought management in groundwater-rich areas
Abstract. Groundwater is a drought resilient source of water supply for many water users globally. Managing these highly-used groundwater stores is complicated by the episodic nature of droughts and by our limited understanding of water systems’ response to extreme events. Models are useful tools to simulate a range of prepared drought interventions, however, we need to ensure robust representation of surface water and groundwater storage, their users, and management interventions for drought resilience. A robust modelling approach is therefore essential for decision-making in groundwater management.
In this study, we present a Socio-Hydrological Water Resource (SHOWER) model for drought management in groundwater-rich regions. We evaluate SHOWER using a response-based and a data-based model evaluation in Great Britain which considers the modelling uncertainty, dynamic impact of management and modelling setups available. In the response-based evaluation, we first examined the model consistency with our understanding of the system functioning and the influence of modelled management scenarios on model simulations. Secondly, we tested the accuracy of heavily influenced discharge and groundwater level simulations in three catchments representative of typical hydrogeological conditions and water management practices in Great Britain (data-based evaluation). In the response-based method, we have found consistent simulations for all model setups and identified which parameters were influential to model output at what times. The data-based analysis shows that calibration can be focused on either source-specific or combined model outputs using a ‘best overall’ calibration approach that captures groundwater levels and low flows. The source-specific calibrations result in the highest and narrowest KGE ranges for discharge and groundwater (KGE: 0.75–0.84 and 0.62–0.95 respectively) with larger ranges using a `best overall' approach (KGE: 0.55–0.79 and 0.27–0.91). Integrated water management interventions have significant impact on flows and groundwater beyond parameter uncertainty and show leverage to reduce droughts by minimising shortages in water demand. With the modular and open-access structure of SHOWER we aim to provide a useful new tool for groundwater managers to explore their management interventions further, increasing drought resilience strategies using a robust modelling approach.