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Connected rivers and their floodplains provide important ecosystem services to humans, such as clean drinking water, sources of nutrition, transportation and recreation. Yet human activity directly or indirectly threatens the aquatic systems’ capacity to provide these services due to structural changes of the river system, such as dam and reservoir construction, or by activities that decrease water quantity and quality.

During my Ph.D. at McGill University, I developed a global river routing model, HydroROUT, to investigate the cumulative impacts of anthropogenic activity at large scales. This approach – grounded in Geographic Information Systems and Science –  integrated the currently best global datasets into a new framework to create novel regional and global-scale, high resolution eco-hydrological models.

As a Post-Doctoral Fellow at McGill, I continue to investigate anthropogenic impacts on the status of rivers, by approaching the topic from three different angles:

1) an essential goal of my work is to create a methodology to assess the connectivity status of global rivers. Together with a group of conservationists and practitioners, I am leading the scientific and technical development of a high-resolution framework to identify Free-Flowing Rivers at the global scale.  The outcome will provide data, tools and methods to integrate connectivity assessments into conservation planning, river health assessments, integrated ecological assessments or strategic hydropower planning at regional or basin scales.

2) in addition, I am interested in estimating the impact of dam development scenarios at basin and global scales and to develop scenario planning models to identify hydropower development scenarios that minimize the impact on environmental and social benchmarks. I recently co-authored a global study on the environmental impact of the currently unfolding global hydropower expansion. The key message of this research is that there are substantial opportunities to reduce the environmental impact by better spatial planning, and other mitigation measures.

3) water quality modelling and environmental risk assessment of contaminants is another focus of my work. Recent work has focused on risk from commonly prescribed pharmaceuticals in the Saint Lawrence River, and natural and synthetic hormones in China and India. As part of a UNESCO pilot project on emerging contaminants, I work towards developing a contaminant Fate Model for continental and global scales.

Publications

Grill, G., Lehner, B., Thieme, M., Geenen, B., Tickner, D., Antonelli, F., Babu, S., Borrelli, P., Cheng, L., Crochetiere, H., Ehalt Macedo, H., Filgueiras, R., Goichot, M., Higgins, J., Hogan, Z., Lip, B., McClain, M., Meng, J., Mulligan, M., Nilsson, C., Olden, J., Opperman, J., Petry, P., Reidy Liermann, C., Saenz, L., Salinas-Rodríguez, S., Schelle, P., Schmitt, R.J.P., Snider, J., Tan, F., Tockner, K., Valdujo, P.H., van Soesbergen, A., Zarfl C. (2019): Mapping the world’s free-flowing rivers. Nature. doi: 10.1038/s41586-019-1111-9

Grill, G., Li, J., Khan, U., Zhong, Y., Lehner, B., Nicell, J., Ariwi, J. (2018) Estimating the eco-toxicological risk of estrogens in China’s rivers using a high-resolution contaminant fate model. Water Research 145, 707-720. doi: 10.1016/j.watres.2018.08.053

Opperman, J., J. Hartmann, J. Raepple, H. Angarita, P. Beames., E. Chapin, R. Geressu, G. Grill, J. Harou, A. Hurford, D. Kammen, R. Kelman, E. Martin, T. Martins, R. Peters, C. Rogéliz, and R. Shirley (2017): The Power of Rivers: A Business Case. The Nature Conservancy: Washington, D.C

Messager, M.L., Lehner, B., Grill, G., Nedeva, I., Schmitt, O. (2016): Estimating the volume and age of water stored in global lakes using a geo-statistical approach. Nature Communications: 13603. doi: 10.1038/ncomms13603 (open access)

Grill, G., Khan, U., Lehner, B., Nicell, J., Ariwi, J. (2015): Risk assessment of down-the-drain chemicals at large spatial scales: Model development and application to contaminants originating from urban areas in the Saint Lawrence River Basin. Science of the Total Environment 541, 825-838.

Opperman, J., Grill, G. and Hartmann, J. (2015): The Power of Rivers – Finding balance between energy and conservation in hydropower development (Washington, DC: The Nature Conservancy). Download key findings here, full white paper here.

Grill, G., Lehner, B., Lumsdon, A.E., MacDonald, G.K., Zarfl, C., Reidy Liermann, C. (2015): An index-based framework for assessing patterns and trends in river fragmentation and flow regulation by global dams at multiple scales. Environmental Research Letters 10 015001. doi:10.1088/1748-9326/10/1/015001 (Open Access)

Grill, G., Ouellet Dallaire, C., Fluet-Chouinard, E., Sindorf, N., Lehner, B. (2014): Development of new indicators to evaluate river fragmentation and flow regulation at large scales: a case study for the Mekong River Basin. Ecological Indicators 45: 148-159. doi: 10.1016/j.ecolind.2014.03.026

McDonald, R.I., Weber, K., Padowski, J., Flörke, M., Schneider, C., Green, P.A., Gleeson, T., Eckman, S., Lehner, B., Balk, D., Boucher, T., Grill, G., Montgomery, M. (2014). Water on an urban planet: Urbanization and the reach of urban water infrastructure. Global Environmental Change 27, 96-105. doi:10.1016/j.gloenvcha.2014.04.022 (Open Access)

Lehner, B. & Grill, G. (2013): “Global river hydrography and network routing: baseline data and new approaches to study the world’s large river systems”. Hydrological Processes 27 (15), 2171-2186. doi: 10.1002/hyp.9740

Selected presentations 

Lehner B., Grill G., Shakya R., Nicell J., and Khan U. (2018): Prediction of household pharmaceutical concentrations in global rivers using a large-scale contaminant fate model. EGU General Assembly. Vienna, Austria (8–13 April 2018)

Grill, G., Lehner, B., Thieme, M.L. et al.: “Global mapping of Free-flowing rivers: Preliminary results”. Invited speaker at International River Symposium, New Delhi (Sept 12-14, 2016).

Grill, G., Thieme, M.L., B. Lehner et al.: “Free-Flowing Rivers: Concept, Assessment and Application”. Invited speaker and panelist at Greater Mekong Forum on Water, Food and Energy, Bangkok (Nov 9-11, 2016).

Thieme, M.L., G. Grill, B. Lehner et al.: “Tracking the status of free-flowing rivers: creating a global registry”. Poster presentation at International Society for River Science (ISRS) Symposium. La Crosse, Wisconsin, USA (Aug. 23-28, 2015).

Grill, G.: “An index-based framework to assess river fragmentation and flow regulation and its application in basin-scale strategic dam planning”. Panel presentation at Fish Passage Conference 2015 in Groningen, Netherlands (June 22-24, 2015).

Grill, G. & Lehner, B.: “Assessing fluvial ecosystem fragmentation at the global scale using high resolution hydrographic and hydrological data.” GWSP Conference in Bonn, Germany: Water in the Anthropocene – Challenges for Science and Governance (May 21-24, 2013).

Grill, G. & Lehner, B.: “HydroSHEDS – New data and tools to assess status and change of the Global River Network and implications for the world’s cities.” World Water Week in Stockholm 2011: Science and Tools for Freshwater Conservation in an Urbanising World (Aug. 25, 2011).

Grill, G., Khan, U, Nicell, J.A. & Lehner, B.: “Assessing the fate and transport of chemicals in rivers and lakes using global scale models: Informing chemical management plans in Canada”. GWSP Conference in Bonn, Germany: Water in the Anthropocene – Challenges for Science and Governance (May 21-24, 2013).

Additional project links: WWF, TNC