Bernard Francou

Bernard Francou
Institute of Research for Development | IRD · 012 - Laboratory for the Study of Transfers in Hydrology and Environment (LTHE)

Director of Research

About

227
Publications
55,660
Reads
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8,136
Citations
Introduction
Mountains and climate change : geomorphology and glaciology Papers reviews and popular Science New book in press about climate change impacts in mountains (Alps and world)
Additional affiliations
September 1991 - September 2013
Institute of Research for Development
Position
  • Research Director
Description
  • Emeritus
January 1984 - October 1990
French National Centre for Scientific Research
Position
  • Chargé de Recherche
Description
  • Geomorphology, Dynamics and Sedimentology of slope deposits in periglacial environments
Education
September 1984 - September 1987
Paris Diderot University
Field of study
  • Gemorphology

Publications

Publications (227)
Preprint
We present a comprehensive study of the evolution of the glaciers in the Antisana ice cap (tropical Andes) over the period 1956–2016. Based on geodetic observations of aerial photographs and high-resolution satellite images, we explore the effects of morpho-topographic and climate variables on glacier volumes. Contrasting behavior was observed over...
Article
Full-text available
Rock glaciers are creeping bodies of ice and rock that account for an important part of the mountain cryosphere. In this study, we investigated long‐term changes of the Laurichard rock glacier (French Alps), to understand how this rock glacier is responding to climate change. Using feature‐tracking and photogrammetric measurements between 1952 and...
Article
Rock glaciers, usually preserved in periglacial environments of cold-climate high-relief regions, are useful (palaeo)climate indicators. In the European Alps, numerous studies have focused on describing these geomorphological features. However, very few have attempted directly dating them. This lack of measurement is particularly evident in the Fre...
Article
Full-text available
Rapid warming is a major threat for the alpine biodiversity but, at the same time, accelerated glacial retreat constitutes an opportunity for taxa and communities to escape range contraction or extinction. We explored the first steps of plant primary succession after accelerated glacial retreat under the assumption that the first few years are crit...
Book
Full-text available
Retrait rapide des glaciers, effondrements, menaces sur l'avenir des stations de ski... C'est sans doute en montagne que les effets du changement climatique sont les plus spectaculaires. Mais qu'en est-il exactement ? Peut-on quantifier l'accélération du réchauffement depuis trois décennies ? En retracer les causes et l'histoire ancienne ? Deux sci...
Book
Full-text available
This book is a synthesis of 40-years surveys in the Combe de Laurichard (Hautes Alpes, French Alps). The study focuses on the present dynamics of talus slope deposits (a new model), snow avalanche deposits and rockglaciers). This rockglacier is one of the most surveyed in the world (velocities, ice content, microclimatology, etc).
Article
Full-text available
We present a basic ablation model combining a positive degree-day approach to calculate melting and a simple equation based on wind speed to compute sublimation. The model was calibrated at point scale (4900 m a.s.l.) on Antizana Glacier 15 (0.28 km2; 0°28' S, 78°09' W) with data from March 2002 to August 2003 and validated with data from January t...
Article
Full-text available
In this paper, we reanalyze the glacier mass balance on Glaciar Antisana 15 α over the 1995–2012 period. Annual glacier mass balances were quantified on the basis of monthly glaciological measurements using an adaptation of Lliboutry's statistical approach. The geodetic mass balance was computed between 1997 and 2009 giving a cumulative balance of...
Article
Full-text available
In this paper, we reanalyze the glacier mass balance on Glaciar Antisana 15α over the 1995–2012 period. Annual glacier mass balances were quantified on the basis of monthly glaciological measurements using an adaptation of Lliboutry’s statistical approach. The geodetic mass balance was computed between 1997 and 2009 giving a cumulative balance of −...
Book
Full-text available
En décembre 2015 se tiendra à Paris la 21 e conférence des Nations-Unies sur le climat, quelques mois après la parution d'un nouveau rapport du Groupe d'experts intergouvernemental sur l'évolution du climat (GIEC). C'est l'occasion de faire le point sur les changements observés sur la « planète glace » au cours des quarante dernières années. La gla...
Article
Full-text available
The supply of glacier water to La Paz city, Bolivia, between 1963 and 2006 was assessed at annual and seasonal timescales based on the mass-balance quantification of 70 glaciers located within the drainage basins of La Paz. Glaciers contributed about 15% of water resources at an annual scale (14% in the wet season, 27% in the dry season). Uncertain...
Article
Full-text available
The Younger Dryas stadial, a cold event spanning 12,800 to 11,500 years ago, during the last deglaciation, is thought to coincide with the last major glacial re-advance in the tropical Andes. This interpretation relies mainly on cosmic-ray exposure dating of glacial deposits. Recent studies, however, have established new production rates for cosmog...
Book
Full-text available
EDITORIAL NOTE The XXVI Scientific Meeting of the Argentine Association of Geophysicists and Geodesists was held in Tucuman, Argentine, November 5-9, 2012. It included numerous contributions from representatives from the neighboring countries. The first issue of GEOACTA Volume 2014 is a Special Edition based on papers carefully selected from the sc...
Article
Full-text available
The longest and most continuous series of measurements of mass balance in the Intertropical Zone correspond to Zongo glacier, Bolivia. Measurements, which were initiated in 1991, were taken using both the hydrological and glaciological methods. Comparison of these results show discrepancies in the mass balances obtained. In order to verify the mass...
Article
Full-text available
A positive degree-day (PDD) model was tested on Antizana Glacier 15$alpha$ (0.28 km2; 0°28' S, 78°09' W) to assess to what extent this approach is suitable for studying glacier mass balance in the inner tropics. Cumulative positive temperatures were compared with field measurements of melting amount and with surface energy balance computations. A s...
Conference Paper
A positive degree-day (PDD) model was tested on Antizana Glacier 15alfa (0.28 km2; 0o28’S, 78o09’W) to assess to what extent this approach is adapted to study glacier mass balance in the inner tropics. Cumulative positive temperature amounts were compared with field measurements of melting and with surface energy balance omputations, showing a sign...
Conference Paper
Full-text available
The glacier mass balance evolution on two glaciers (Antisana Glacier 12 and Antisana Glacier 15) in the tropical Andes is presented. To this end, photogrammetry technique was applied on aerial images taken at five dates: 1956, 1965, 1979, 1997 and 2009. For each date, digital elevation models (DEMs) were generated with an average vertical accuracy...
Conference Paper
Full-text available
Under tropical conditions, water discharge from glaciers is crucial for water resources in the dry season, as it is the case for La Paz, Bolivia (16S). In the current study, the glacier water supply of La Paz city has been assessed at annual and seasonal time-scale for the first time thanks to the mass balance analysis of 70 glaciers located within...
Data
Full-text available
The principal aspects addressed are the relationships between transport processes and depositional environments, and the sedimentary properties of the deposits. The following "process-product' models are discussed: (a) stone-banked solifluction sheets or lobes, (b) dry grain flows and frost-coated clast flows, (c) debris flows, and (d) niveo-aeolia...
Article
Full-text available
A positive degree day (PDD) model was tested against surface energy balance results on Antizana Glacier 15 (0.7 km2; 0o28'S, 78o09'W) to assess whether PDD models may reflect the local physical ablation processes in the tropical Andes. Modeling at one point shows that daily ablation processes are sometimes incorrectly reproduced by the PDD model be...
Conference Paper
Full-text available
Since the seventies an important increase in atmospheric temperature testifies of the global climate change. In relationship with this temperature increase a significant recession of tropical glaciers has been observed. However, the timing and magnitude of glacier change at a regional scale remain poorly studied because of the insufficiency of dire...
Conference Paper
Full-text available
This presentation provides a comprehensive overview of the studies of glaciers in the tropical Andes conducted in recent decades leading to the current status of the glaciers in the context of climate change. In terms of changes in surface area and length, we show that the glacier retreat in the tropical Andes over the last three decades is unprece...
Article
Full-text available
The aim of this paper is to provide the community with a comprehensive overview of the studies of glaciers in the tropical Andes conducted in recent decades leading to the current status of the glaciers in the context of climate change. In terms of changes in surface area and length, we show that the glacier retreat in the tropical Andes over the l...
Article
Full-text available
The aim of this paper is to provide the community with a comprehensive overview of the studies of glaciers in the tropical Andes conducted in recent decades leading to the current status of the glaciers in the context of climate change. In terms of changes in surface area and length, we show that the glacier retreat in the tropical Andes over the l...
Data
The Laurichard active rock glacier is the permafrost-related landform with the longest record of monitoring in France, including an annual geodetic survey, repeated geoelectrical campaigns from 1979 onwards and continuous recording of ground temperature since 2003. These data were used to examine changes in creep rates and internal structure from 1...
Article
Full-text available
This paper describes several simple positive degree-day models (hereafter referred as "PDD models") designed to provide past climatic reconstruction from tropical glacier paleo-equilibrium altitude lines (paleo-ELA). Several ablation laws were tested and calibrated using the monthly ablation and meteorological data recorded from 1997 to 2006 on the...
Article
Full-text available
The comparison of two shallow ice cores recovered in 1999 and 2000 from the same place on the Chimborazo summit glacier revealed the influence of the coincident Tungurahua volcanic eruption on their stable isotope and chemical records. The surface snow melting and water percolation induced from the ash deposition caused a preferential elution and r...
Article
Full-text available
The comparison of two shallow ice cores recovered in 1999 and 2000 from the same place on the Chimborazo summit glacier revealed the influence of the coincident Tungurahua volcanic eruption on their stable isotope and chemical records. The surface snow melting and water percolation induced from the ash deposition caused a preferential elution and r...
Conference Paper
Full-text available
Los aportes de agua de origen glaciar al suministro de agua potable para la ciudad Quito (2.440.000 de habitantes en 2008), capital del Ecuador, se estiman entre un 2% y 4% del total anual de agua potencialmente consumida (5.6 m3 s-1). Sin embargo a nivel local, en una cuenca de 15.1 km2 del volcán Antisana, con 15% de cobertura glaciar y 85% de pá...
Conference Paper
The present contribution compiles research on the most important periglacial areas with permafrost in South America. Included are monitoring of the active layer, permafrost table and different types of permafrost in the Peruvian Andes; Bolivian Altiplano; Chilean Desert Andes; Northwest Argentina (Puna, Cordillera Oriental, Nevados and Aconquija re...
Article
Full-text available
Preliminary hydro glacier estimates indicate that glacier contribution to the average annual consumption (5.6 m3 s-1) of the city of Quito (Capital of Ecuador, ~2'500.000 inhabitants, 2800 masl) represents only about 2%-4% of the total supply for human consumption. However, at the local level at the Antizana volcano (0°28'S, 78°09'W), the mass bala...
Article
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Offrir à un large public le bilan de ces recherches à travers un panorama complet de l'état des glaciers dans le monde, tel est l'objectif principal de cet ouvrage. La glace et les glaciers, mémoires des climats du passé, y sont resitués dans le temps long, depuis 10 000 ans, avec une attention particulière pour le Petit Age Glaciaire (XIVe-XIXe) e...
Article
Full-text available
The aim of this paper is to document the evolution of glaciers in the tropical Andes (between 10°N and 16°S) for the last millennium, based on moraines dated by lichenometry and radiocarbon, lake sediment records and historical documents. Viewed collectively, several glacial advances occurred synchronously. The first advance is dated around AD 1200...
Article
The Laurichard active rock glacier is the permafrost-related landform with the longest record of monitoring in France, including an annual geodetic survey, repeated geoelectrical campaigns from 1979 onwards and continuous recording of ground temperature since 2003. These data were used to examine changes in creep rates and internal structure from 1...
Article
Full-text available
Les glaciers sont devenus des outils indispensables pour surveiller l'évolution de notre environnement planétaire et la question est de savoir si, dans leur phase de repli actuel, les glaciers sont à la veille de sortir de la variabilité qu'ils ont connue au cours de l'holocène. Après avoir rappelé leurs fluctuations importantes à l'échelle des der...
Article
Full-text available
The longest continuous glaciological mass-balance time-series in the intertropical zone of South America goes back to 1991 on Glaciar Zongo, Bolivia. Photogrammetric and hydrological data have been used to (1) check the specific net balance over long periods and (2) extend the mass-balance time series over the last 50 years. These data reveal a bia...
Article
Full-text available
The volume changes of 21 glaciers in the Cordillera Real have been determined between 1963 and 2006 using photogrammetric measurements. These data form the longest series of mass balances obtained with such accuracy in the tropical Andes. Our analysis reveals that temporal mass balance fluctuations are similar, revealing a common response to climat...
Conference Paper
Full-text available
Thanks to the IRD (Institut de Recherche pour l’Environnement, France) and local Andean institutions, a permanent observation network including glaciological mass balance, hydrological balance and locally, energy balance, could be maintained from 1991-1995 to date on a dozen of glaciers from Bolivia, Peru and Ecuador. We present a very synthetic vi...
Article
Dating moraines by lichenometry enabled us to reconstruct glacier recession in the Bolivian Andes since the Little Ice Age maximum. On the 15 proglacial margins studied, we identified a system of ten principal moraines that marks the successive positions of glaciers over the last four centuries. Moraines were dated by performing statistical analysi...
Article
Full-text available
Observations on glacier extent from Ecuador, Peru and Bolivia give a detailed and unequivocal account of rapid shrinkage of tropical Andean glaciers since the Little Ice Age (LIA). This retreat however, was not continuous but interrupted by several periods of stagnant or even advancing glaciers, most recently around the end of the 20th century. New...
Article
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Hydrological and glaciological data were gathered in the watershed (1.37 km) of the Antizana Glacier 15 (0.7 km) in the periods 1997–2002 and 1995–2005, respectively. In addition, tracer experiments were carried out to analyse the flow through permeable morainic deposits located between the glacier snout and the runoff gauging station. Over 11 year...
Article
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A glaciological program has been undertaken since 1991 on Zongo glacier in Bolivia (6000–4850 m asl, 2.4 km2, 16°S). This program involves mass balance measurements, hydrological studies and energy balance investigations. On outer-tropical glaciers, melting and snow accumulation are both maximum in the wet season (austral summer), whereas the dry s...
Article
Full-text available
In the Andes, runoff from glacierized basins is an important element of water budgets, assuring year-round flows for agriculture, potable water, power generation, and ecosystem integrity. Thus, changes induced by tropical glacier retreat constitute an early case of the need for adaptation and the type and size of associated economic and social impa...
Article
Andean alpine glaciers are in rapid retreat, as witnessed by actual measurements, comparative imagery and popular memory. Overall glacier losses will diminish future water availability for human consumption as well as for lahar generation, the product of mixing incandescent eruptive materials with glacial ice and snow. The field study and modeling...
Article
A method for analysing the segmentation in the profile of talus slopes is used in an Alpine periglacial environment. Two populations of talus slope profiles are examined according to the development of their headwalls. Beneath massive rockwalls the profile appears bi-segmented: a break point situated at a constant angle (33–34 degrees) divides an e...
Article
Full-text available
We have 10 years of mass balance, meteorology and precipitation data on glacier 15 of Antizana, located in Ecuador, very close to the equator. Starting with the results of Francou et al. (2004), we studied the relation of monthly ablation zone volume variations of the glacier with 20 variables chosen to represent the global and local climate. The s...
Article
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Esta sección 8 se inicia con una revisión de los principales resultados de las mediciones sobre la evolución de los glaciares tropicales. Luego, se analizan los datos de balance de masa en Bolivia y Ecuador desde principios de los noventa, para lo cual se ha utilizado información medida en toda la superficie del glaciar para resaltar el hecho de qu...
Article
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Esta sección 21 describe el tipo de información climática que se puede obtener del estudio del balance de masa. Los datos anuales se encuentran directamente relacionados con (i), la acumulación de nieve, la cual depende tanto de precipitaciones como de avalanchas de nieve o hielo y vientos; y (ii), la ablación, la cual representa directamente el Ba...
Article
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En ciertos lugares 24 , el retroceso de los glaciares ha ocasionado la formación de grandes lagos formados por materiales fácilmente erosionables. En regiones sísmicas como los Andes peruanos o los Himalayas, la probabilidad de que estos diques se quiebren es lo suficientemente alta como para que las lagunas constituyan una amenaza latente. Por lo...