Groundwater ecohydrology: GIScience tools to forecast change and sustainability of global ecosystems, studies in Africa, Europe and North America

Abstract. This study examines the interface between groundwater hydrology and ecology, and addresses a scientific grand challenge to develop a comprehensive, systematic understanding of continental water dynamics by linking the hydrosphere and biosphere. There exists a current lack of data interoperability between groundwater modeling tools due to differences in numerical techniques – Analytic Element Method (AEM), Finite Difference Method (FDM), and Finite Element Method (FEM) – which lend themselves well to either vector or raster data, and legacy input/output file formats that are not well suited across models. Nonetheless, investigative computational tools are all founded in the same conceptualization of hydrologic properties associated with mass, flux, pathways and residence time. A consistent framework is developed using modern Geographic Information Science (GIScience) methods to organize and archive important information from international datasets and previous groundwater ecohydrology studies organized around aquifer and water point, line, polygon and raster features. Case studies illustrate the efficacy of this platform to address existing data interoperability issues for representative groundwater ecohydrology problems of global significance including the impact of human-induced forcings, change in species, and forcings by natural processes on groundwater ecohydrology. In North America, we study the relationships between groundwater pumping in the Ogallala Aquifer and changes in riparian habitat and phreatophyte species composition. In Europe, we study the impacts of changes in forest species composition on groundwater recharge and baseflow to biologically diverse fens and wetlands in the Veluwe sand hill region of The Netherlands. In Africa, we study the wetlands of the Okavango Delta in Botswana that forms an oasis in the midst of the Kalahari Desert and the role of groundwater in flushing salts from this freshwater ecosystem. In each study, we document the current state of knowledge, identify pertinent datasets and previous studies, develop new conceptual and computer models, and summarize findings. This computational platform provides a framework to study sustainability, to forecast the impacts of changes in forcings, and to provide a scientific underpinning that informs management and public policy debate.