Léonard El-Hokayem


My Research Project


Identifying threatened groundwater dependent ecosystems as local biodiversity hotspots in Saxony-Anhalt and globally via remote sensing

Groundwater resources are biodiversity hotspots, and provide crucial ecosystems services. Yet, groundwater dependent ecosystems (GDEs) are exposed to several anthropogenic threats, including climate change. Tackling these threats requires improving the on-the-ground identification of GDEs at the global scale. In order to close critical gaps in current global GDE monitoring capacity, we will use existing vegetation databases and tap the potentials of remote sensing together with the ever-emerging variety of global datasets from different disciplines to map GDEs at the global scale and assess threats to these local hotspots of biodiversity. The approach will combine elaboration, analysis and interpretation of existing global hydrological data sets regarding ecosystems reliant on emerging groundwater and a novel designed methodology to identify those ecosystems reliant on resident groundwater (terrestrial vegetation).

The following research questions will be addressed to test the hypothesis:

1) Which biome-specific indicator sets and tools must be specified to develop a GDE mapping framework applicable to the global scale?

2) How could GDEs be detected globally with an ecosystem-based, combined vegetation related and hydrological approach?

3) How can existing but heterogeneous together with novel validation data (e.g. polygons vs. in situ point records, hydrological vs. ecological observations) complement one another to enable robust, global-scale validation of GDE maps?

4) Which GDEs that are assessed as hotspots of biodiversity are threatened by and vulnerable to land use change and climate change?

PAC TEAM: Christopher Conrad (MLU, iDiv), Francesco Maria Sabatini (University of Bologna, iDiv), Carsten Meyer (iDiv), Jonathan Everts (MLU), Muhammad Usman (MLU)

Short CV


since 01/2022Doctoral researcher at the Martin Luther University Halle-Wittenberg in cooperation with iDiv
08/2019 – 12/2019Semester abroad at the Western Norway University of Applied Sciences
10/2018 – 12/2021

M.Sc. Geography at the Martin Luther University Halle-Wittenberg with focus on Geoecology and Geospatial Data Handling;

Master thesis: ‘Identification of groundwater dependent vegetation using remote sensing data – a Mediterranean case study’

10/2017 – 10/2020Funding through the Deutschlandstipendium for talented and high-performing students

10/2015 – 09/2018

B.Sc. Geography at the Martin Luther University Halle-Wittenberg;

Bachelor thesis: ‘Extreme habitat city - Historical change of tree species in single-family housing estates in Leipzig with evaluation of the suitability for the scenario anthropogenic climate change.’



Link, A., El-Hokayem, L., Usman, M., Conrad, C., Reinecke, R., Berger, M., Wada, Y., Coroama, V., Finkbeiner, M.

(2023): Groundwater-dependent ecosystems at risk - global hotspot analysis and implications. Environmental Research Letters

El-Hokayem, L., De Vita, P., Conrad, C.

(2023): Local identification of groundwater dependent vegetation using high-resolution Sentinel-2 data – A Mediterranean case study. Ecological Indicators
Icon institutes

Martin-Luther-Universität Halle-Wittenberg

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