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Jojo Geo

Geoscience environment de Toulouse, Géosciences Environnement Toulouse (GET, OMP), Department Member

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Associated professor at Toulouse university from 1998, I work on Earth sciences and geophysics to study water cycle, river morphology, erosion rate.
Phone: +33561332665
Address: GET, UMR CNRS 5563, OMP (Paul Sabatier University)
14 avenue Edouard Belin
31400
Toulouse (France)

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alejandro monsivais

Flinders University of South Australia

Justino Martínez

Ignasi Corbella

Miriam Pablos Hernández

Universitat Politecnica de Catalunya

falguni bhattacharya

Institute of Seismologic Research

Università degli Studi di Padova

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Papers by Jojo Geo

Soil moisture monitoring over wetland areas using GNSS signals

Theme: Land -Presentation: Oral For many scientists, climate warming induces an increases in evap... more Theme: Land -Presentation: Oral For many scientists, climate warming induces an increases in evaporation and precipitation leading to an acceleration of the water cycle. Soil moisture is a key parameter to study the water cycle variations. At global scale it controls the exchange of water and heat between the land surface and the atmosphere through plant evapotranspiration. At local/regional scale is also a relevant parameter. Well knowledge of the soil moisture is of paramount importance for ecological processes, agriculture applications even more considering that is expected an increase of a 45% in the water demands. Therefore, its knowledge will be essential to optimize the use of the fresh water, which in turn will allow to distribute it better, and to improve the quantity and quality of the crop production. In addition, soil moisture, can be useful to predict when excess rainfall can cause water logging and/or flooding instead, it also useful to prevent droughts.

Use of reflected GNSS SNR data to retrieve either soil moisture or vegetation height from a wheat crop

by Jojo Geo and Nicolas Roussel

This work aims to estimate soil moisture and vegetation height from Global Navigation Satellite S... more This work aims to estimate soil moisture and vegetation height from Global Navigation Satellite System (GNSS) Signal to Noise Ratio (SNR) data using direct and reflected signals by the land surface surrounding a ground-based antenna. Observations are collected from a rainfed wheat field in southwestern France. Surface soil moisture is retrieved based on SNR phases estimated by the Least Square Estimation method, assuming the relative antenna height is constant. It is found that vegetation growth breaks up the constant relative antenna height assumption. A vegetation-height retrieval algorithm is proposed using the SNR-dominant period (the peak period in the average power spectrum derived from a wavelet analysis of SNR). Soil moisture and vegetation height are retrieved at different time periods (before and after vegetation's significant growth in March). The retrievals are compared with two independent reference data sets: in situ observations of soil moisture and vegetation height, and numerical simulations of soil moisture, vegetation height and above-ground dry biomass from the ISBA (interactions between soil, biosphere and atmosphere) land surface model. Results show that changes in soil moisture mainly affect the multipath phase of the SNR data (assuming the relative antenna height is constant) with little change in the dominant period of the SNR data, whereas changes in vegetation height are more likely to modulate the SNR-dominant period. Surface volumetric soil moisture can be estimated (R 2 = 0.74, RMSE = 0.009 m 3 m −3) when the wheat is smaller than one wavelength (∼ 19 cm). The quality of the estimates markedly decreases when the vegetation height increases. This is because the reflected GNSS signal is less affected by the soil. When vegetation replaces soil as the dominant reflecting surface, a wavelet analysis provides an accurate estimation of the wheat crop height (R 2 = 0.98, RMSE = 6.2 cm). The latter correlates with modeled above-ground dry biomass of the wheat from stem elongation to ripening. It is found that the vegetation height retrievals are sensitive to changes in plant height of at least one wavelength. A simple smoothing of the retrieved plant height allows an excellent matching to in situ observations, and to modeled above-ground dry biomass.

MISTRALE: Soil moisture mapping service based on a RPAS-embedded GNSS-Reflectometry sensor

Around 70 percent of worldwide freshwater is used by agriculture. To be able to feed an additiona... more Around 70 percent of worldwide freshwater is used by agriculture. To be able to feed an additional 2 billion people by 2030, water demand is expected to increase tremendously in the next decades. Farmers are challenged to produce “more crop per drop”. In order to optimize water resource management, it is crucial to improve soil moisture situation awareness. Basically, this implies the improvement of both the temporal and the spatial resolution of soil moisture measurements. Records from classical humidity probes are punctual and are not representative of the soil moisture of the plot at a local scale, and monitoring an entire parcel is not realistic for operational applications. With the advent of remote sensing, soil moisture can be systematically monitored at the global scale but at the expense of the temporal and/or spatial resolution. Even with the SMOS satellite mission [1], the repetitivity of the measurements is three days, which is not sufficient to monitor diurnal variations. Alternatively, recent studies suggested to take advantage of the electromagnetic waves, continuously emitted by the Global Navigation Satellite System (GNSS) satellite constellations, to retrieve different geophysical parameters of the Earth surface. This opportunistic remote sensing technique, known as GNSS reflectometry (GNSS-R), consists in comparing the direct signals (i.e., the signals directly travelling from the satellite to the receiver) with those reflected by the ground. It offers a wide range of applications in Earth sciences and particularly in soil moisture monitoring. It namely presents the advantage of sensing a whole surface around the antenna (see, e.g., [2], [3], [4]). Moreover, since GNSS signals lies in L-band, the GNSS-R is operational under cloud cover and during the night. It is less sensitive to variation on the thermal background. Yet, GNSS-R measurements are affected by soil roughness and by vegetation. It is nevertheless worth noting that the roughness impact can be mitigated using polarimetric measurements and computing the apparent reflectivity for both left-hand and right-hand circular polarizations of the reflected signals. Next to this, the attenuation of the reflected signal due to vegetation can be taken into account by using a corrective term (e.g, based on NDVI measurements). Two main approaches can be considered: (i) the waveform one, which consists in comparing the amplitude of the direct and reflected GNSS complex waveforms (i.e. basically the correlator’s output), and (ii) the Signal-to-Noise Ratio (SNR) method, based on the
NAVITEC 2016
analysis of the SNR collected by a single GNSS antenna. The advantage of the latter is that it does not require a reflectometrydedicated GNSS receiver, since SNR is an output of classical receivers. The drawback is that this method is mainly designed for ground-based applications. Authors of this study are part of a H2020 project called MISTRALE (Monitoring soIl moisture and water-flooded Areas for agriculture and Environment), which aims at developing an airborne GNSS-R system (RPAS platform) to provide soil moisture maps to decision makers in water management, like farmers and water boards and nature management. This project wants to integrate various technologies to reach commercialization with these GNSS-R based soil moisture maps. The aim of this paper is to present the current status of this project and the results obtained with two preliminary airborne campaigns, based on the SNR technique.

Smectite as a marker of telogenetic process along structural heterogeneities of sedimentary basin: case study of the Eocene submarine slide surfaces of the Ainsa Basin

by Jojo Geo and Laureanne Bourrieres

– Fluid circulation in sedimentary basins is responsible for the transformation and cementation o... more – Fluid circulation in sedimentary basins is responsible for the transformation and cementation of mineral grains during diagenesis. Concretions and pipe chimneys are obvious features resulting from such circulation but some transformations in the matrix of rocks, if less spectacular, may lead to pervasive transformations of the sediments. Inherited slide surfaces in the Eocene Ainsa Basin (Spanish Pyrenees) have been chosen to test this hypothesis. In the Sobrarbe delta, the steady mineralogy of marls indicates homogeneity of the sedimentary source. Enrichment of montmorillonite is only observed close to scar surfaces and in the infilling of the scars. Scanning electron microscope (SEM) observation reveals that smectites are formed by in situ replacement of detrital mafic minerals resulting by transformation of detrital minerals under the action of cold sedimentary fluids, lower than 75 °C. The indications of low temperature conditions and local fluid circulation both support a meteoric origin of the fluids postdating the burial history, probably during an exhumation of the basin associated with the tectonic uplift. The higher smectite contents in the infilling of scars and along the unconformities of slide surfaces reveals enhanced circulation of fluids in under-consolidated sediments and the effective fluid circulation pathways along inherited slide surfaces. Résumé – La smectite comme marqueur des processus télogénétiques le long des structures d'hétérogénéités sédimentaires : cas des surfaces de glissement Eocènes du bassin d'Ainsa. Les circulations de fluides dans les bassins sédimentaires sont responsables de transformation et de cimentation de grains minéraux dans le domaine de la diagenèse. Les concrétions et les cheminées minéralisées sont des constructions résultant de telles circulations mais les transformations de la matrice rocheuse, bien que moins spectaculaires, peuvent conduire à la transformation profonde des sédiments. Les surfaces de glissements héritées du bassin Eocène d'Ainsa ont été choisies pour tester cette contribution. Dans le delta du Sobrarbe, la stabilité de la minéralogie des marnes atteste de l'homogénéité de la source sédimentaire. L'enrichissement en montmorillonite n'est observé qu'à proximité des surfaces de glissement et dans le remplissage de ces cicatrices. L'observation au MEB révèle que les smectites se forment par remplacement et transformation in situ de minéraux détritiques ferromagnésiens sous l'action de fluides sédimentaires froids, moins de 75 °C. Les indications de conditions de basses températures et la circulation locale des fluides supportent l'idée d'une origine météorique des fluides postérieurement à l'histoire de l'enfouissement, probablement durant l'exhumation du bassin associée au soulèvement tectonique. Les plus fortes teneurs en smectites sont observées dans le remplissage des cicatrices et le long des surfaces de glissement, elles révèlent la circulation préférentielle des fluides dans les sédiments sous-compactés et le long des hétérogénéités constituées par les anciennes surfaces de glissement. Mots clés : smectites / diagenèse / circulation de fluides / surfaces de glissement / basin d'Ainsa / hétérogénéité

CAN GNSS-R BE USED TO MONITORING AND MAPPING MINING WASTE DEPOSIT AND ITS ASSOCIATED CONTAMINATION

by Jojo Geo and HA Minh Cuong

Our study aims to develop innovative and inexpensive methods based on remote sensing using a clas... more Our study aims to develop innovative and inexpensive methods based on remote sensing using a classical GNSS receiver to map the contamination (heavy metal) of soils in mining area. GNSS-Reflectometry consists to recover the electromagnetic signals emitted continuously by the GNSS satellites and then reflected on the Earth surface. Our study used GNSS multipath that corresponds to an interference of the ground reflected wave with the direct wave that adds new frequencies affecting the GNSS measurements recorded by the receiver. The ground contamination in mining area pollution affects the composition of soil that can be quantified with GNSS-Reflectometry by measuring relative permittivity changes correlated to the increased or decreased of heavy metal concentration changing the electric conductivity. The studied area is located near Cartagena, SouthEast Spain. We present here the first measurement results.

Forebulge dynamics and environmental control in Western Amazonia: The case study of the Arch of Iquitos (Peru)

by Stéphane Brusset and Jojo Geo

Tectonophysics, 2005

The Iquitos Arch corresponds to a broad topographic high in the Western Amazonia. Morphostructura... more The Iquitos Arch corresponds to a broad topographic high in the Western Amazonia. Morphostructural and geophysical data and flexural modeling show that the Iquitos Arch is the present-day forebulge of the Northwestern Amazonian foreland basin. A detailed tectono-sedimentary study of the Neogene and Quaternary deposits of the Iquitos area has been carried out in order to circumscribe the timing of the forebulge uplift and its environmental consequences. The Neogene and Quaternary sedimentary succession of the Iquitos Arch consists of six formations that evolved from tidal to fluvial environments. The first three formations exhibit Late Miocene gliding features and synsedimentary normal faults. Such soft-sediment deformations bear witness to tectonic activity ascribed to the growth of the forebulge. Regional erosive surfaces that separate the Neogene and Quaternary formations recorded the progressive forebulge emersion and the evolution of Amazonian drainage system. This uplift is related to an increase in tectonic activity within the Andes, which has provoked the eastern propagation of the orogenic wedge and caused an orogenic loading stage in the Amazonian foreland basin system. The emersion of the forebulge induced the retreat of the Pebas bmarine megalakeQ nearby the Iquitos area and consequently caused important environmental changes in the Amazonian basin. From the end of the Late Miocene to the Pliocene, the forebulge acted as a barrier inducing the deposition of fluvial deposits in the forebulge depozone and the deposition of the bWhite SandQ deposits in the backbulge depozone. Since about 6 Ma, the forebulge is incised and crossed over by the modern Amazon River. The Iquitos forebulge is still growing as shown by the faulted Holocene terrace deposits. D

The normalised optimised anisotropicw avelet coefficient (NOAWC) method' An image processingt ool for multi-scale analysis of rock fabric

The 2D Anisotropic Wavelet Transform( 2DAWT) is an image analysis tool which is able to decipher ... more The 2D Anisotropic Wavelet Transform( 2DAWT) is an image analysis tool which is able to decipher signals where information obtained from different scales are inter- mixed.E xtended from the Optimised Anisotropic Wavelet Co- efficientm ethod (OAWC) of Ouillon et al. [1995], we presenta methodw hich discriminatesth e objects and groupso f objects dependingo n their area, shaper atio, orientationa nd position. Illustratedi n a synthetic example, we show that this method allows one to distinguishb etween different sub-populationso f objectsw ithin a singlep hase, and quantify the anisotropieso f shape, orientation and spatial distribution at different scales (objects, clusters of objects, alignments of objects or clus- ters). Applied to a natural rock sample (Sidobre granite, Mon- tagneN oire, France),t he 2DAWT hasp ermitted us to detecta nd accuratelyc haracterise the differentl evels of mineral organisa- tion, and thus,t o contributet o the understandingo f the physi- cal processes,s uch as crystallisation, fluid migration, defor- mation, etc... responsiblef or such organisations.
Philippe Gaillot, José Darrozes Guy Ouillon and Michel de Saint Blanquat

The Black Top Hat function applied to a DEM: A tool to estimate recent incision in a mountainous watershed (Estibere Watershed, Central Pyrenees)

The Top Hat Transform function is a grey-level image analysis tool that allows extracting peaks a... more The Top Hat Transform function is a grey-level image analysis tool that allows extracting peaks and valleys in a nonuniform background. This function can be applied onto a greylevel Digital Elevation Model (DEM). It is herein applied to quantify the volume of recent incised material in a mountainous Pyrenean watershed. Grey-level Closing operation applied to the Present-Day DEM gives a new image called ‘‘paleo’’ DEM. The Black Top Hat function consists in the subtraction of the ‘‘paleo’’ DEM with the Present-Day DEM. It gives a new DEM representing all valleys whose sizes range between the size of the structuring element and the null value as no threshold is used. The calculation of the incised volume is directly derived from the subtraction between the two DEM’s. The geological significance of the quantitative results is discussed.
Felipe Rodriguez, Eric Maire, Pierre Courjault-Rade, and Jose Darrozes

Feedbacks between geomorphology and biota controlling Earth surface processes and landforms: A review of foundation concepts and current understandings

This review article presents recent advances in the ﬁeld of biogeomorphology related to the recip... more This review article presents recent advances in the ﬁeld of biogeomorphology related to the reciprocal coupling between Earth surface processes and landforms, and ecological and evolutionary processes. The aim is to present to the Earth Science community ecological and evolutionary concepts and associated recent conceptual developments for linking geomorphology and biota. The novelty of the proposed perspective is that (1) in the presence of geomorphologic-engineer species, which modify sediment and landform dynamics, natural selection operating at the scale of organisms may have consequences for the physical components of ecosystems, and particularly Earth surface processes and landforms; and (2) in return, these modiﬁcations of geomorphologic processes and landforms often feed back to the ecological characteristics of the ecosystem (structure and function) and thus to biological characteristics of engineer species and/or other species (adaptation and speciation). The main foundation concepts from ecology and evolutionary biology which have led only recently to an improved conception of landform dynamics in geomorphology are reviewed and discussed. The biogeomorphologic macroevolutionary insights proposed explicitly integrate geomorphologic niche-dimensions and processes within an ecosystem framework and reﬂect current theories of eco-evolutionary and ecological processes. Collectively, these lead to the deﬁnition of an integrated model describing the overall functioning of biogeomorphologic systems over ecological and evolutionary timescales.

Variability in erosion rates related to the state of landscape transience in the semi-arid Chilean Andes

by Jojo Geo and Germán Aguilar

We quantify erosion rates in the higher sectors of the Huasco Valley, in the Main Cordillera of t... more We quantify erosion rates in the higher sectors of the Huasco Valley, in the Main Cordillera of the semi-arid Andes of Chile, using elevation differences between three successive geomorphic markers (pediments and paleo-valleys) and the present day valley. Available Ar-Ar ages of Neogene pediments are used to estimate mean erosion rates for the three periods (16 to 13 My, 13 to 8 My, and following 8 My). The landscape of the Huasco Valley is in a transient state, as indicated by well-preserved pediment surfaces in interfluves, valleys deeply incised by fluvial and glacial erosion and scarped head-valleys that represent the current knick-zones. Higher erosion rates (45–75m/My) are calculated for the more recent period (< 8 My) during which deep incision developed compared to previous periods (6–31m/My). Quantitative data indicate that glaciers had a much higher erosional capability than fluvial activity in the higher sectors of the Main Cordillera. Comparison with erosion rates calculated in other drainage basins of the Chilean Andes suggests that the variability of erosion rates depends on the landscape’s transient erosive state. The landscape’s geomorphologic response to the uplift of the Main Cordillera results in the retreat of aknickzone, for whichretreat velocity depends on precipitation rate pattern and glacial erosion intensity.

Temporal relations between meander deformation, water discharge and sediment ﬂuxes in the ﬂoodplain of the Rio Beni (Bolivian Amazonia)

The Andean Cordillera and piedmont signiﬁcantly inﬂuence river system and dynamics, being the sou... more The Andean Cordillera and piedmont signiﬁcantly inﬂuence river system and dynamics, being the source of many of the important rivers of the Amazon basin. The Beni River, whose upper sub-catchments drain the Andean and sub-Andean ranges, is a major tributary of the Madeira River. This study examines the river in the south-western Amazonian lowlands of Bolivia, where it develops mobile meanders. Channel migration, meander-bend morphology and ox-bow lakes are analysed at different temporal and spatial scales. The ﬁrst part of this study was undertaken with the aim to link the erosion–deposition processes in the active channel with hydrological events. The quantiﬁcation of annual erosion and deposition areas shows high inter-annual and spatial variability. In this study, we investigate the conditions of sediment exportation in the river in relation to three hydrological parameters (ﬂood intensity, date of discharge peak and duration of the bank-full stage level). The second part of this study, focusing on the abandoned meanders, analyses the cutoff processes and the post-abandonment evolution during 1967–2001. This approach shows the inﬂuence of the active channel behaviour on the sediment diffusion and sequestration of the abandoned meanders and allows us to build a ﬁrst model of the contemporary ﬂoodplain evolution. Copyright © 2006 John Wiley & Sons, Ltd.

Soil moisture monitoring over wetland areas using GNSS signals

Theme: Land -Presentation: Oral For many scientists, climate warming induces an increases in evap... more Theme: Land -Presentation: Oral For many scientists, climate warming induces an increases in evaporation and precipitation leading to an acceleration of the water cycle. Soil moisture is a key parameter to study the water cycle variations. At global scale it controls the exchange of water and heat between the land surface and the atmosphere through plant evapotranspiration. At local/regional scale is also a relevant parameter. Well knowledge of the soil moisture is of paramount importance for ecological processes, agriculture applications even more considering that is expected an increase of a 45% in the water demands. Therefore, its knowledge will be essential to optimize the use of the fresh water, which in turn will allow to distribute it better, and to improve the quantity and quality of the crop production. In addition, soil moisture, can be useful to predict when excess rainfall can cause water logging and/or flooding instead, it also useful to prevent droughts.

Use of reflected GNSS SNR data to retrieve either soil moisture or vegetation height from a wheat crop

by Jojo Geo and Nicolas Roussel

This work aims to estimate soil moisture and vegetation height from Global Navigation Satellite S... more This work aims to estimate soil moisture and vegetation height from Global Navigation Satellite System (GNSS) Signal to Noise Ratio (SNR) data using direct and reflected signals by the land surface surrounding a ground-based antenna. Observations are collected from a rainfed wheat field in southwestern France. Surface soil moisture is retrieved based on SNR phases estimated by the Least Square Estimation method, assuming the relative antenna height is constant. It is found that vegetation growth breaks up the constant relative antenna height assumption. A vegetation-height retrieval algorithm is proposed using the SNR-dominant period (the peak period in the average power spectrum derived from a wavelet analysis of SNR). Soil moisture and vegetation height are retrieved at different time periods (before and after vegetation's significant growth in March). The retrievals are compared with two independent reference data sets: in situ observations of soil moisture and vegetation height, and numerical simulations of soil moisture, vegetation height and above-ground dry biomass from the ISBA (interactions between soil, biosphere and atmosphere) land surface model. Results show that changes in soil moisture mainly affect the multipath phase of the SNR data (assuming the relative antenna height is constant) with little change in the dominant period of the SNR data, whereas changes in vegetation height are more likely to modulate the SNR-dominant period. Surface volumetric soil moisture can be estimated (R 2 = 0.74, RMSE = 0.009 m 3 m −3) when the wheat is smaller than one wavelength (∼ 19 cm). The quality of the estimates markedly decreases when the vegetation height increases. This is because the reflected GNSS signal is less affected by the soil. When vegetation replaces soil as the dominant reflecting surface, a wavelet analysis provides an accurate estimation of the wheat crop height (R 2 = 0.98, RMSE = 6.2 cm). The latter correlates with modeled above-ground dry biomass of the wheat from stem elongation to ripening. It is found that the vegetation height retrievals are sensitive to changes in plant height of at least one wavelength. A simple smoothing of the retrieved plant height allows an excellent matching to in situ observations, and to modeled above-ground dry biomass.

MISTRALE: Soil moisture mapping service based on a RPAS-embedded GNSS-Reflectometry sensor

Around 70 percent of worldwide freshwater is used by agriculture. To be able to feed an additiona... more Around 70 percent of worldwide freshwater is used by agriculture. To be able to feed an additional 2 billion people by 2030, water demand is expected to increase tremendously in the next decades. Farmers are challenged to produce “more crop per drop”. In order to optimize water resource management, it is crucial to improve soil moisture situation awareness. Basically, this implies the improvement of both the temporal and the spatial resolution of soil moisture measurements. Records from classical humidity probes are punctual and are not representative of the soil moisture of the plot at a local scale, and monitoring an entire parcel is not realistic for operational applications. With the advent of remote sensing, soil moisture can be systematically monitored at the global scale but at the expense of the temporal and/or spatial resolution. Even with the SMOS satellite mission [1], the repetitivity of the measurements is three days, which is not sufficient to monitor diurnal variations. Alternatively, recent studies suggested to take advantage of the electromagnetic waves, continuously emitted by the Global Navigation Satellite System (GNSS) satellite constellations, to retrieve different geophysical parameters of the Earth surface. This opportunistic remote sensing technique, known as GNSS reflectometry (GNSS-R), consists in comparing the direct signals (i.e., the signals directly travelling from the satellite to the receiver) with those reflected by the ground. It offers a wide range of applications in Earth sciences and particularly in soil moisture monitoring. It namely presents the advantage of sensing a whole surface around the antenna (see, e.g., [2], [3], [4]). Moreover, since GNSS signals lies in L-band, the GNSS-R is operational under cloud cover and during the night. It is less sensitive to variation on the thermal background. Yet, GNSS-R measurements are affected by soil roughness and by vegetation. It is nevertheless worth noting that the roughness impact can be mitigated using polarimetric measurements and computing the apparent reflectivity for both left-hand and right-hand circular polarizations of the reflected signals. Next to this, the attenuation of the reflected signal due to vegetation can be taken into account by using a corrective term (e.g, based on NDVI measurements). Two main approaches can be considered: (i) the waveform one, which consists in comparing the amplitude of the direct and reflected GNSS complex waveforms (i.e. basically the correlator’s output), and (ii) the Signal-to-Noise Ratio (SNR) method, based on the
NAVITEC 2016
analysis of the SNR collected by a single GNSS antenna. The advantage of the latter is that it does not require a reflectometrydedicated GNSS receiver, since SNR is an output of classical receivers. The drawback is that this method is mainly designed for ground-based applications. Authors of this study are part of a H2020 project called MISTRALE (Monitoring soIl moisture and water-flooded Areas for agriculture and Environment), which aims at developing an airborne GNSS-R system (RPAS platform) to provide soil moisture maps to decision makers in water management, like farmers and water boards and nature management. This project wants to integrate various technologies to reach commercialization with these GNSS-R based soil moisture maps. The aim of this paper is to present the current status of this project and the results obtained with two preliminary airborne campaigns, based on the SNR technique.

Smectite as a marker of telogenetic process along structural heterogeneities of sedimentary basin: case study of the Eocene submarine slide surfaces of the Ainsa Basin

by Jojo Geo and Laureanne Bourrieres

– Fluid circulation in sedimentary basins is responsible for the transformation and cementation o... more – Fluid circulation in sedimentary basins is responsible for the transformation and cementation of mineral grains during diagenesis. Concretions and pipe chimneys are obvious features resulting from such circulation but some transformations in the matrix of rocks, if less spectacular, may lead to pervasive transformations of the sediments. Inherited slide surfaces in the Eocene Ainsa Basin (Spanish Pyrenees) have been chosen to test this hypothesis. In the Sobrarbe delta, the steady mineralogy of marls indicates homogeneity of the sedimentary source. Enrichment of montmorillonite is only observed close to scar surfaces and in the infilling of the scars. Scanning electron microscope (SEM) observation reveals that smectites are formed by in situ replacement of detrital mafic minerals resulting by transformation of detrital minerals under the action of cold sedimentary fluids, lower than 75 °C. The indications of low temperature conditions and local fluid circulation both support a meteoric origin of the fluids postdating the burial history, probably during an exhumation of the basin associated with the tectonic uplift. The higher smectite contents in the infilling of scars and along the unconformities of slide surfaces reveals enhanced circulation of fluids in under-consolidated sediments and the effective fluid circulation pathways along inherited slide surfaces. Résumé – La smectite comme marqueur des processus télogénétiques le long des structures d'hétérogénéités sédimentaires : cas des surfaces de glissement Eocènes du bassin d'Ainsa. Les circulations de fluides dans les bassins sédimentaires sont responsables de transformation et de cimentation de grains minéraux dans le domaine de la diagenèse. Les concrétions et les cheminées minéralisées sont des constructions résultant de telles circulations mais les transformations de la matrice rocheuse, bien que moins spectaculaires, peuvent conduire à la transformation profonde des sédiments. Les surfaces de glissements héritées du bassin Eocène d'Ainsa ont été choisies pour tester cette contribution. Dans le delta du Sobrarbe, la stabilité de la minéralogie des marnes atteste de l'homogénéité de la source sédimentaire. L'enrichissement en montmorillonite n'est observé qu'à proximité des surfaces de glissement et dans le remplissage de ces cicatrices. L'observation au MEB révèle que les smectites se forment par remplacement et transformation in situ de minéraux détritiques ferromagnésiens sous l'action de fluides sédimentaires froids, moins de 75 °C. Les indications de conditions de basses températures et la circulation locale des fluides supportent l'idée d'une origine météorique des fluides postérieurement à l'histoire de l'enfouissement, probablement durant l'exhumation du bassin associée au soulèvement tectonique. Les plus fortes teneurs en smectites sont observées dans le remplissage des cicatrices et le long des surfaces de glissement, elles révèlent la circulation préférentielle des fluides dans les sédiments sous-compactés et le long des hétérogénéités constituées par les anciennes surfaces de glissement. Mots clés : smectites / diagenèse / circulation de fluides / surfaces de glissement / basin d'Ainsa / hétérogénéité

CAN GNSS-R BE USED TO MONITORING AND MAPPING MINING WASTE DEPOSIT AND ITS ASSOCIATED CONTAMINATION

by Jojo Geo and HA Minh Cuong

Our study aims to develop innovative and inexpensive methods based on remote sensing using a clas... more Our study aims to develop innovative and inexpensive methods based on remote sensing using a classical GNSS receiver to map the contamination (heavy metal) of soils in mining area. GNSS-Reflectometry consists to recover the electromagnetic signals emitted continuously by the GNSS satellites and then reflected on the Earth surface. Our study used GNSS multipath that corresponds to an interference of the ground reflected wave with the direct wave that adds new frequencies affecting the GNSS measurements recorded by the receiver. The ground contamination in mining area pollution affects the composition of soil that can be quantified with GNSS-Reflectometry by measuring relative permittivity changes correlated to the increased or decreased of heavy metal concentration changing the electric conductivity. The studied area is located near Cartagena, SouthEast Spain. We present here the first measurement results.

Forebulge dynamics and environmental control in Western Amazonia: The case study of the Arch of Iquitos (Peru)

by Stéphane Brusset and Jojo Geo

Tectonophysics, 2005

The Iquitos Arch corresponds to a broad topographic high in the Western Amazonia. Morphostructura... more The Iquitos Arch corresponds to a broad topographic high in the Western Amazonia. Morphostructural and geophysical data and flexural modeling show that the Iquitos Arch is the present-day forebulge of the Northwestern Amazonian foreland basin. A detailed tectono-sedimentary study of the Neogene and Quaternary deposits of the Iquitos area has been carried out in order to circumscribe the timing of the forebulge uplift and its environmental consequences. The Neogene and Quaternary sedimentary succession of the Iquitos Arch consists of six formations that evolved from tidal to fluvial environments. The first three formations exhibit Late Miocene gliding features and synsedimentary normal faults. Such soft-sediment deformations bear witness to tectonic activity ascribed to the growth of the forebulge. Regional erosive surfaces that separate the Neogene and Quaternary formations recorded the progressive forebulge emersion and the evolution of Amazonian drainage system. This uplift is related to an increase in tectonic activity within the Andes, which has provoked the eastern propagation of the orogenic wedge and caused an orogenic loading stage in the Amazonian foreland basin system. The emersion of the forebulge induced the retreat of the Pebas bmarine megalakeQ nearby the Iquitos area and consequently caused important environmental changes in the Amazonian basin. From the end of the Late Miocene to the Pliocene, the forebulge acted as a barrier inducing the deposition of fluvial deposits in the forebulge depozone and the deposition of the bWhite SandQ deposits in the backbulge depozone. Since about 6 Ma, the forebulge is incised and crossed over by the modern Amazon River. The Iquitos forebulge is still growing as shown by the faulted Holocene terrace deposits. D

The normalised optimised anisotropicw avelet coefficient (NOAWC) method' An image processingt ool for multi-scale analysis of rock fabric

The 2D Anisotropic Wavelet Transform( 2DAWT) is an image analysis tool which is able to decipher ... more The 2D Anisotropic Wavelet Transform( 2DAWT) is an image analysis tool which is able to decipher signals where information obtained from different scales are inter- mixed.E xtended from the Optimised Anisotropic Wavelet Co- efficientm ethod (OAWC) of Ouillon et al. [1995], we presenta methodw hich discriminatesth e objects and groupso f objects dependingo n their area, shaper atio, orientationa nd position. Illustratedi n a synthetic example, we show that this method allows one to distinguishb etween different sub-populationso f objectsw ithin a singlep hase, and quantify the anisotropieso f shape, orientation and spatial distribution at different scales (objects, clusters of objects, alignments of objects or clus- ters). Applied to a natural rock sample (Sidobre granite, Mon- tagneN oire, France),t he 2DAWT hasp ermitted us to detecta nd accuratelyc haracterise the differentl evels of mineral organisa- tion, and thus,t o contributet o the understandingo f the physi- cal processes,s uch as crystallisation, fluid migration, defor- mation, etc... responsiblef or such organisations.
Philippe Gaillot, José Darrozes Guy Ouillon and Michel de Saint Blanquat

The Black Top Hat function applied to a DEM: A tool to estimate recent incision in a mountainous watershed (Estibere Watershed, Central Pyrenees)

The Top Hat Transform function is a grey-level image analysis tool that allows extracting peaks a... more The Top Hat Transform function is a grey-level image analysis tool that allows extracting peaks and valleys in a nonuniform background. This function can be applied onto a greylevel Digital Elevation Model (DEM). It is herein applied to quantify the volume of recent incised material in a mountainous Pyrenean watershed. Grey-level Closing operation applied to the Present-Day DEM gives a new image called ‘‘paleo’’ DEM. The Black Top Hat function consists in the subtraction of the ‘‘paleo’’ DEM with the Present-Day DEM. It gives a new DEM representing all valleys whose sizes range between the size of the structuring element and the null value as no threshold is used. The calculation of the incised volume is directly derived from the subtraction between the two DEM’s. The geological significance of the quantitative results is discussed.
Felipe Rodriguez, Eric Maire, Pierre Courjault-Rade, and Jose Darrozes

Feedbacks between geomorphology and biota controlling Earth surface processes and landforms: A review of foundation concepts and current understandings

This review article presents recent advances in the ﬁeld of biogeomorphology related to the recip... more This review article presents recent advances in the ﬁeld of biogeomorphology related to the reciprocal coupling between Earth surface processes and landforms, and ecological and evolutionary processes. The aim is to present to the Earth Science community ecological and evolutionary concepts and associated recent conceptual developments for linking geomorphology and biota. The novelty of the proposed perspective is that (1) in the presence of geomorphologic-engineer species, which modify sediment and landform dynamics, natural selection operating at the scale of organisms may have consequences for the physical components of ecosystems, and particularly Earth surface processes and landforms; and (2) in return, these modiﬁcations of geomorphologic processes and landforms often feed back to the ecological characteristics of the ecosystem (structure and function) and thus to biological characteristics of engineer species and/or other species (adaptation and speciation). The main foundation concepts from ecology and evolutionary biology which have led only recently to an improved conception of landform dynamics in geomorphology are reviewed and discussed. The biogeomorphologic macroevolutionary insights proposed explicitly integrate geomorphologic niche-dimensions and processes within an ecosystem framework and reﬂect current theories of eco-evolutionary and ecological processes. Collectively, these lead to the deﬁnition of an integrated model describing the overall functioning of biogeomorphologic systems over ecological and evolutionary timescales.

Variability in erosion rates related to the state of landscape transience in the semi-arid Chilean Andes

by Jojo Geo and Germán Aguilar

We quantify erosion rates in the higher sectors of the Huasco Valley, in the Main Cordillera of t... more We quantify erosion rates in the higher sectors of the Huasco Valley, in the Main Cordillera of the semi-arid Andes of Chile, using elevation differences between three successive geomorphic markers (pediments and paleo-valleys) and the present day valley. Available Ar-Ar ages of Neogene pediments are used to estimate mean erosion rates for the three periods (16 to 13 My, 13 to 8 My, and following 8 My). The landscape of the Huasco Valley is in a transient state, as indicated by well-preserved pediment surfaces in interfluves, valleys deeply incised by fluvial and glacial erosion and scarped head-valleys that represent the current knick-zones. Higher erosion rates (45–75m/My) are calculated for the more recent period (< 8 My) during which deep incision developed compared to previous periods (6–31m/My). Quantitative data indicate that glaciers had a much higher erosional capability than fluvial activity in the higher sectors of the Main Cordillera. Comparison with erosion rates calculated in other drainage basins of the Chilean Andes suggests that the variability of erosion rates depends on the landscape’s transient erosive state. The landscape’s geomorphologic response to the uplift of the Main Cordillera results in the retreat of aknickzone, for whichretreat velocity depends on precipitation rate pattern and glacial erosion intensity.

Temporal relations between meander deformation, water discharge and sediment ﬂuxes in the ﬂoodplain of the Rio Beni (Bolivian Amazonia)

The Andean Cordillera and piedmont signiﬁcantly inﬂuence river system and dynamics, being the sou... more The Andean Cordillera and piedmont signiﬁcantly inﬂuence river system and dynamics, being the source of many of the important rivers of the Amazon basin. The Beni River, whose upper sub-catchments drain the Andean and sub-Andean ranges, is a major tributary of the Madeira River. This study examines the river in the south-western Amazonian lowlands of Bolivia, where it develops mobile meanders. Channel migration, meander-bend morphology and ox-bow lakes are analysed at different temporal and spatial scales. The ﬁrst part of this study was undertaken with the aim to link the erosion–deposition processes in the active channel with hydrological events. The quantiﬁcation of annual erosion and deposition areas shows high inter-annual and spatial variability. In this study, we investigate the conditions of sediment exportation in the river in relation to three hydrological parameters (ﬂood intensity, date of discharge peak and duration of the bank-full stage level). The second part of this study, focusing on the abandoned meanders, analyses the cutoff processes and the post-abandonment evolution during 1967–2001. This approach shows the inﬂuence of the active channel behaviour on the sediment diffusion and sequestration of the abandoned meanders and allows us to build a ﬁrst model of the contemporary ﬂoodplain evolution. Copyright © 2006 John Wiley & Sons, Ltd.