Bernhard Lehner’s research while affiliated with McGill University and other places

What is this page?


This page lists works of an author who doesn't have a ResearchGate profile or hasn't added the works to their profile yet. It is automatically generated from public (personal) data to further our legitimate goal of comprehensive and accurate scientific recordkeeping. If you are this author and want this page removed, please let us know.

Publications (126)


Figure 4. MAmax and MAmin maps of GIEMS-MCISW (1992 to 2020), GIEMS-MCISW+P (1992 to 2020), and WAD2M (2000 to 2020) over the Ob, as well as GLWDv2 (static) peatland map. Low MAmin are due to the snow mask.
Figure 5. MAmax and MAmin maps over the Sudd region of GIEMS-MCISW, GIEMS-MCISW+P (1992 to 2020), WAD2M (2000 to 2020) and CYGNSS-based estimates from Gerlein-Safdi et al. (2021) (2017-Jun to 2020-Apr) and Zeiger et al. (2023) (2018-Aug to 2020-Jul). The available periods differ between the products.
Figure 6. MAmax and MAmin maps of GIEMS-MCISW (1992 to 2020), GIEMS-MCISW+P (1992 to 2020), and WAD2M (2000 to 2020) over the Amazon basin.
Figure 7. MAmax and MAmin maps of GIEMS-MCISW (1992 to 2020), GIEMS-MCISW+P (1992 to 2020), and WAD2M (2000 to 2020) over South-East Asia.
Figure 8. Left: Monthly mean seasonal cycle of GIEMS-MCISW, GIEMS-MCISW+P, and WAD2M over different regions. Right: Deseasonalized monthly anomalies of the same three variables. To derive the deseasonalized monthly anomalies, the average monthly seasonal cycle was subtracted from the long term monthly time series. For the Sudd basin seasonality comparison, estimations from Gerlein-Safdi et al. (2021) (2017-06 to 2020-04) and Zeiger et al. (2023) (2018-08 to 2020-07) are added.

+2

The GIEMS-MethaneCentric database: a dynamic and comprehensive global product of methane-emitting aquatic areas
  • Preprint
  • File available

October 2024

·

105 Reads

Juliette Bernard

·

·

·

[...]

·

The Global Inundation Extent from Multi-Satellites (GIEMS) database first published in 2001 (Prigent et al., 2001) was a key advance toward the accurate representation of wetlands globally by providing dynamic time series of global surface water based on passive microwave observations. This study supplements the second version of GIEMS (GIEMS-2) with other datasets to produce GIEMS-MethaneCentric (GIEMS-MC), a dynamically mapped dataset of methane-emitting waterlogged and inundated ecosystems. We separated open water from wetlands in GIEMS-MC by using the Global Lakes and Wetlands Database version 2 (GLWDv2), while adding unsaturated peatland areas undetected by GIEMS-2. Rice paddies are identified using the Monthly Irrigated and Rainfed Crop Areas (MIRCA2000) product. A specific coastal zone filtering is applied to avoid ocean artifacts while preserving coastal wetlands. GIEMS-MC covers the period 1992–2020 on a monthly scale at 0.25°x0.25° spatial resolution. The GIEMS-MC product includes two layers of monthly wetland time series – one for flooded and saturated wetlands and another for all wetlands and peatlands – together with seven layers of compatible static maps of open water bodies (lakes, rivers, reservoirs) and seasonal rice paddy maps used in its production. The dominant vegetation and wetland types per pixel are also provided in GIEMS-MC variables. GIEMS-MC is compared to Wetland Area and Dynamics for Methane Modelling (WAD2M), a dataset providing dynamic wetland information. In terms of wetland extent, GIEMS-MC all wetlands and peatlands and WAD2M show similar results, with a mean annual maximum of 7.8 Mkm2 for GIEMS-MC and 6.8 Mkm2 for WAD2M, and similar spatial patterns in most regions. The GIEMS-MC seamless time series represents a significant advance in wetland representation for methane modelling, although limitations remain in the accurate identification of rice, coastal and peatland areas. This resource provides harmonized dynamic maps of aquatic methane emitting surfaces and is available at https://zenodo.org/records/13919645.

Download

The Global Dam Watch database of river barrier and reservoir information for large-scale applications

October 2024

·

481 Reads

·

4 Citations

Scientific Data

There are millions of river barriers worldwide, ranging from wooden locks to concrete dams, many of which form associated impoundments to store water in small ponds or large reservoirs. Besides their benefits, there is growing recognition of important environmental and social trade-offs related to these artificial structures. However, global datasets describing their characteristics and geographical distribution are often biased towards particular regions or specific applications, such as hydropower dams affecting fish migration, and are thus not globally consistent. Here, we present a new river barrier and reservoir database developed by the Global Dam Watch (GDW) consortium that integrates, harmonizes, and augments existing global datasets to support large-scale analyses. Data curation involved extensive quality control processes to create a single, globally consistent data repository of instream barriers and reservoirs that are co-registered to a digital river network. Version 1.0 of the GDW database contains 41,145 barrier locations and 35,295 associated reservoir polygons representing a cumulative storage capacity of 7,420 km³ and an artificial terrestrial surface water area of 304,600 km².



Streamflow Intermittence in Europe: Estimating High‐Resolution Monthly Time Series by Downscaling of Simulated Runoff and Random Forest Modeling

July 2024

·

174 Reads

·

3 Citations

Knowing where and when rivers cease to flow provides an important basis for evaluating riverine biodiversity, biogeochemistry and ecosystem services. We present a novel modeling approach to estimate monthly time series of streamflow intermittence at high spatial resolution at the continental scale. Streamflow intermittence is quantified at more than 1.5 million river reaches in Europe as the number of no‐flow days grouped into five classes (0, 1–5, 6–15, 16–29, 30–31 no‐flow days) for each month from 1981 to 2019. Daily time series of observed streamflow at 3706 gauging stations were used to train and validate a two‐step random forest modeling approach. Important predictors were derived from time series of monthly streamflow at 73 million 15 arc‐sec (∼500 m) grid cells that were computed by downscaling the 0.5 arc‐deg (∼55 km) output of the global hydrological model WaterGAP, which accounts for human water use. Of the observed perennial and non‐perennial station‐months, 97.8% and 86.4%, respectively, were correctly predicted. Interannual variations of the number of non‐perennial months at non‐perennial reaches were satisfactorily simulated, with a median Pearson correlation of 0.5. While the spatial prevalence of non‐perennial reaches is underestimated, the number of non‐perennial months is overestimated in dry regions of Europe where artificial storage abounds. Our model estimates that 3.8% of all European reach‐months and 17.2% of all reaches were non‐perennial during 1981–2019, predominantly with 30–31 no‐flow days. Although estimation uncertainty is high, our study provides, for the first time, information on the continent‐wide dynamics of non‐perennial rivers and streams.


Mapping the world’s inland surface waters: an update to the Global Lakes and Wetlands Database (GLWD v2)

July 2024

·

983 Reads

·

2 Citations

In recognition of the importance of inland waters, numerous datasets mapping their extents, types, or changes have been created using sources ranging from historical wetland maps to real-time satellite remote sensing. However, differences in definitions and methods have led to spatial and typological inconsistencies among individual data sources, confounding their complementary use and integration. The Global Lakes and Wetlands Database (GLWD), published in 2004, with its globally seamless gridded depiction of major vegetated and non-vegetated wetland classes, has emerged over the last decades as a foundational reference map that has advanced research and conservation planning addressing freshwater biodiversity, ecosystem services, greenhouse gas emissions, land surface processes, hydrology, and human health. Here, we present a new iteration of this map, termed GLWD version 2, generated by harmonizing the latest ground- and satellite-based data products into one single database. Following the same design principle as its predecessor, GLWD v2 aims to avoid double-counting of overlapping surface water features while differentiating between natural and non-natural lakes, rivers of multiple sizes, and several other wetland types. The classification of GLWD v2 incorporates information on seasonality (i.e., permanent vs. intermittent vs. ephemeral); inundation vs. saturation (i.e., flooding vs. waterlogged soils); vegetation cover (e.g., forested swamps vs. non-forested marshes); salinity (e.g., salt pans); natural vs. non-natural origins (e.g., rice paddies); and a stratification of landscape position and water source (e.g., riverine, lacustrine, palustrine, coastal/marine). GLWD v2 represents 33 wetland classes and—including all intermittent classes—depicts a maximum of 18.2 million km2 of wetlands (13.4 % of the global land area excluding Antarctica). The spatial extent of each class is provided as the fractional coverage within each grid cell at a resolution of 15 arc-seconds (approximately 500 m at the equator), with cell fractions derived from input data at resolutions as small as 10 m. The updated GLWD v2 offers an improved representation of inland surface water extents and their classification for contemporary conditions. Despite being a static map, it includes classes that denote intrinsic temporal dynamics. GLWD v2 is designed to facilitate large-scale hydrological, ecological, biogeochemical, and conservation applications, aiming to support the study and protection of wetland ecosystems around the world.





Global Lake Health in the Anthropocene: Societal Implications and Treatment Strategies

April 2024

·

941 Reads

·

5 Citations

The world's 1.4 million lakes (≥10 ha) provide many ecosystem services that are essential for human well‐being; however, only if their health status is good. Here, we reviewed common lake health issues and classified them using a simple human health‐based approach to outline that lakes are living systems that are in need of oxygen, clean water and a balanced energy and nutrient supply. The main reason for adopting some of the human health terminology for the lake health classification is to increase the awareness and understanding of global lake health issues. We show that lakes are exposed to various anthropogenic stressors which can result in many lake health issues, ranging from thermal, circulatory, respiratory, nutritional and metabolic issues to infections and poisoning. Of particular concern for human well‐being is the widespread lake drying, which is a severe circulatory issue with many cascading effects on lake health. We estimated that ∼115,000 lakes evaporate twice as much water as they gain from direct precipitation, making them vulnerable to potential drying if inflowing waters follow the drying trend, putting more than 153 million people at risk who live in close vicinity to those lakes. Where lake health issues remain untreated, essential ecosystem services will decline or even vanish, posing a threat to the well‐being of millions of people. We recommend coordinated multisectoral and multidisciplinary prevention and treatment strategies, which need to include a follow‐up of the progress and an assessment of the resilience of lakes to intensifying threats. Priority should be given to implementing sewage water treatment, mitigating climate change, counteracting introductions of non‐native species to lakes and decreasing uncontrolled anthropogenic releases of chemicals into the hydro‐, bio‐, and atmosphere.


HydroFATE (v1): a high-resolution contaminant fate model for the global river system

April 2024

·

111 Reads

·

1 Citation

Pharmaceuticals and household chemicals are neither fully consumed nor fully metabolized when routinely used by humans, thereby resulting in the emission of residues down household drains and into wastewater collection systems. Since treatment systems cannot entirely remove these substances from wastewaters, the contaminants from many households connected to sewer systems are continually released into surface waters. Furthermore, diffuse contributions of wastewaters from populations that are not connected to treatment systems can directly (i.e., through surface runoff) or indirectly (i.e., through soils and groundwater) contribute to contaminant concentrations in rivers and lakes. The unplanned and unmonitored release of such contaminants can pose important risks to aquatic ecosystems and ultimately human health. In this work, the contaminant fate model HydroFATE is presented, which is designed to estimate the surface-water concentrations of domestically used substances for virtually any river in the world. The emission of compounds is calculated based on per capita consumption rates and population density. A global database of wastewater treatment plants is used to separate the effluent pathways from populations into treated and untreated and to incorporate the contaminant pathways into the river network. The transport in the river system is simulated while accounting for processes of environmental decay in streams and in lakes. To serve as a preliminary performance evaluation and proof of concept of the model, the antibiotic sulfamethoxazole (SMX) was chosen, due to its widespread use and the availability of input and validation data. The comparison of modelled concentrations against a compilation of reported SMX measurements in surface waters revealed reasonable results despite inherent model uncertainties. A total of 409 000 km of rivers were predicted to have SMX concentrations that exceed environmental risk thresholds. Given the high spatial resolution of predictions, HydroFATE is particularly useful as a screening tool to identify areas of potentially elevated contaminant exposure and to guide where local monitoring and mitigation strategies should be prioritized.


Citations (80)


... Since hydrological and environmental phenomena occur with a time lag compared to meteorological phenomena; consequently, climate change may cause unforeseen effects on other phenomena affecting the water cycle and environmental factors such as precipitation infiltration, surface runoff, evaporation and land cover, and so on. These phenomena may also influence the quantity and quality of groundwater resources (Sharafati et al. 2020;Cuthbert et al. 2019;Trichakis et al. 2011;Döll 2009). Moreover, the effects of global warming and climate change on the hydrosphere and biosphere are currently being observed, threatening the sustainability of water resources and ecosystems (Liu et al. 2020). ...

Reference:

Groundwater level prediction based on GMS and SVR models under climate change conditions: Case Study—Talesh Plain
Global patterns and dynamics of climate–groundwater interactions
  • Citing Article
  • January 2019

Nature Climate Change

... With input from several hundred contributors, from government departments to local stakeholders, this database includes over 100,000 recorded river barriers of all sizes and types, demonstrating that such efforts are possible-at least on a national scale and providing that there is a state-of-art baseline on which to continue building the database for future monitoring and management. 50 . One drawback of this approach is that the information on barriers is often dispersed across various agencies and reports (in some cases from different countries and languages), making it challenging to access. ...

The Global Dam Watch database of river barrier and reservoir information for large-scale applications

Scientific Data

... Considering the uncertainties of UpCH4 in the tropics due to limited site samples, we also calculated CH 4 emissions using observational data from a specific FLUXNET-CH4 site in Brazil's Pantanal wetland (BR-Npw) (Vourlitis et al., 2020). Although the Sudd and the Pantanal are located on two different continents, they are both categorized into riverine seasonally flooded wetlands in the latest Global Lakes and Wetlands Database version 2 (Lehner et al., 2024), and their wetland dynamics are both highly sensitive to precipitation during wet seasons (Gerlein-Safdi et al., 2021). More information about the similarity between these two wetlands is provided in Table S1 in Supporting Information S1. ...

Mapping the world’s inland surface waters: an update to the Global Lakes and Wetlands Database (GLWD v2)

... This makes them particularly useful for addressing the curse of dimensionality in logistic regression and for modeling data with complex patterns. This model has been used to produce LSWT products [44]. These steps are carried out at the pixel level. ...

Surface water temperature observations and ice phenology estimations for 1.4 million lakes globally

Remote Sensing of Environment

... 13 This transition is accompanied by a decline in taxonomic and functional diversities while nutrient availability increases, leading to ecological degradation, economic losses, and threats to drinking water safety. 10,43,44 Our study provides a sign of global shallow lakes transitioning toward shaded or turbid states. The shaded state is transitional, and interrupting FEAV dominance often results in a shift toward a turbid state dominated by phytoplankton, particularly under high nutrient loads. ...

Global Lake Health in the Anthropocene: Societal Implications and Treatment Strategies

... Despite their utility, ABMs have rarely been applied to understand complex interactions and feedback between spatiotemporally dynamic contaminants and animal movement, particularly in terms of within-population variation in movement. Such approaches are increasingly feasible given the increase in modern computing power and the development and refinement of contaminant fate models [125]. Integrating spatial and temporal information on contaminant concentrations at a local scale into ABM approaches will be critical in predicting how individual variability in movement and behaviour affects exposure to contaminants, providing insights into the potential long-term effects on population dynamics. ...

HydroFATE (v1): a high-resolution contaminant fate model for the global river system

... Freshwater comprises 2.5% of the total water on the planet of which just 1.2% is stored on the surface with less than a quarter unfrozen liquid freshwater of lakes, rivers, and wetlands (www.usgs.gov/media/images/distribution-water-and-above-earth). Water is unevenly distributed, and most of the world's lakes are located above the 40° N northern latitude (Lehner 2024). For example, Canada, the second largest country of the world, has over half of the world's freshwater lakes (https://reviewlution.ca/resources/how-many-lakes-in-canada/, ...

Rivers and Lakes—Their Distribution, Origins, and Forms
  • Citing Chapter
  • January 2024

... There are numerous studies on this topic, highlighting the importance of research in maintaining and improving water quality. These studies conducted in various countries and river systems contribute to a better understanding of the factors affecting water quality and the measures that can be taken to mitigate these issues [5][6][7][8][9][10][11][12][13][14][15]. ...

The future of global river health monitoring

... Thus, alkalinity additions to river systems imply more inorganic carbon being stably transported downstream and less CO 2 evasion. This supports the idea that direct river alkalinization might be a viable mitigation solution (Sterling et al., 2024). ...

Title: Addition of Alkalinity to Rivers: a new CO2 Removal Strategy

... Freshwater lakes are noteworthy yet not well-constrained sources of GHG [34][35][36][37] . Yet, their emission profiles remain enigmatic, hindered by the absence of extensive and differentiated GHG flux measurements from diverse lake types, particularly those with intricate river-lake interconnections 38,39 . Our findings found that the GHG dynamics within interconnected river-lake systems, exemplified by Dongting Lake in China, exhibit a distinctive temporal flux pattern. ...

Inland Water Greenhouse Gas Budgets for RECCAP2: 1. State‐Of‐The‐Art of Global Scale Assessments