Understanding the sensitivity of karst groundwater recharge to climate and land cover changes at a large-scale

Abstract

Karst aquifers are an important source of fresh water for agricultural activities and domestic use in many regions of the world. However, groundwater depletion has already started to occur in some karst regions, while future changes in climate, land cover and population will likely exacerbate this issue. Karst areas are highly permeable and produce large amounts of groundwater recharge. As a result, groundwater recharge in these systems may be particularly sensitive to climate and land cover changes compared to less permeable systems. Yet, little effort has been directed toward assessing the impact of climate and land cover change in karst areas at large-scales. This research aims to fill this gap by investigating and developing novel methodologies and a novel hydrological model that enable such an assessment and by analysing the sensitivity of simulated recharge over carbonate rock areas in Europe, the Middle East and Northern Africa.

Firstly, we examine the implementation of Global Sensitivity Analysis (GSA) that has been identified as a key methodology in the context of this thesis to support model development and to identify modelled controls. We introduce novel criteria to assess the robustness of GSA results. Secondly, we propose the first large-scale hydrological model including an explicit representation of vegetation and karst properties (V2Karst). We demonstrate the plausibility of the model predictions at carbonate rock FLUXNET sites using GSA. Thirdly, we apply the V2Karst model and GSA techniques to assess the relative sensitivity of recharge to climate and land cover change across Europe, the Middle East and Northern Africa. Our results reveal that the degree of subsurface heterogeneity of the karst system, the precipitation intensity and the land cover type are important controls of recharge that should be carefully considered in future modelling experiments and in future water and land cover management strategies.

Date of Award	25 Sept 2018
Original language	English
Awarding Institution	University of Bristol
Supervisor	Francesca Pianosi (Supervisor) & Thorsten Wagener (Supervisor)