Development and validation of a short version of the Partnership Self-Assessment Tool (PSAT) among professionals in Dutch disease-management partnerships

Background: The extent to which partnership synergy is created within quality improvement programmes in the Netherlands is unknown. In this article, we describe the psychometric testing of the Partnership Self-Assessment Tool (PSAT) among professionals in twenty-two disease-management partnerships participating in quality improvement projects focused on chronic care in the Netherlands. Our objectives are to validate the PSAT in the Netherlands and to reduce the number of items of the original PSAT while maintaining validity and reliability. Methods. The Dutch version of the PSAT was tested in twenty-two disease-management partnerships with 218 professionals. We tested the instrument by means of structural equation modelling, and examined its validity and reliability. Results: After eliminating 14 items, the confirmatory factor analyses revealed good indices of fit with the resulting 15-item PSAT-Short version (PSAT-S). Internal consistency as represented by Cronbach's alpha ranged from acceptable (0.75) for the 'efficiency' subscale to excellent for the 'leadership' subscale (0.87). Convergent validity was provided with high correlations of the partnership dimensions and partnership synergy (ranged from 0.512 to 0.609) and high correlations with chronic illness care (ranged from 0.447 to 0.329). Conclusion: The psychometric properties and convergent validity of the PSAT-S were satisfactory rendering it a valid and reliable instrument for assessing partnership syne

SN 2009ip at late times - an interacting transient at+2 years

We present photometric and spectroscopic observations of the interacting transient SN 2009ip taken during the 2013 and 2014 observing seasons. We characterize the photometric evolution as a steady and smooth decline in all bands, with a decline rate that is slower than expected for a solely Co-56-powered supernova at late phases. No further outbursts or eruptions were seen over a two year period from 2012 December until 2014 December. SN 2009ip remains brighter than its historic minimum from pre-discovery images. Spectroscopically, SN 2009ip continues to be dominated by strong, narrow (less than or similar to 2000 km s(-1)) emission lines of H, He, Ca, and Fe. While we make tenuous detections of [Fe II] lambda 7155 and [O I] lambda lambda 6300, 6364 lines at the end of 2013 June and the start of 2013 October, respectively, we see no strong broad nebular emission lines that could point to a core-collapse origin. In general, the lines appear relatively symmetric, with the exception of our final spectrum in 2014 May, when we observe the appearance of a redshifted shoulder of emission at +550 km s(-1). The lines are not blueshifted, and we see no significant near-or mid-infrared excess. From the spectroscopic and photometric evolution of SN 2009ip until 820 d after the start of the 2012a event, we still see no conclusive evidence for core-collapse, although whether any such signs could be masked by ongoing interaction is unclear

Altimetry for the future: Building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the ‘‘Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

DMTs and Covid-19 severity in MS: a pooled analysis from Italy and France

We evaluated the effect of DMTs on Covid-19 severity in patients with MS, with a pooled-analysis of two large cohorts from Italy and France. The association of baseline characteristics and DMTs with Covid-19 severity was assessed by multivariate ordinal-logistic models and pooled by a fixed-effect meta-analysis. 1066 patients with MS from Italy and 721 from France were included. In the multivariate model, anti-CD20 therapies were significantly associated (OR = 2.05, 95%CI = 1.39–3.02, p < 0.001) with Covid-19 severity, whereas interferon indicated a decreased risk (OR = 0.42, 95%CI = 0.18–0.99, p = 0.047). This pooled-analysis confirms an increased risk of severe Covid-19 in patients on anti-CD20 therapies and supports the protective role of interferon

Altimetry for the future: building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Suivi des plans d'eau en Afrique de l'Ouest par télédétection : analyse du régime hydrologique par une approche multi-capteurs et classification par réseau de neurones

West Africa count numerous water bodies, including lakes, ponds and reservoirs, often small ones, crucial for local populations which use them on a daily basis. Despite their importance, these resources are under-studied, mainly due to a lack of in situ data. Remote sensing data allow studying continental surface waters, but the spatial and temporal resolution of the instruments has often been an obstacle to studying these small, highly dynamic objects over time. Today, improvements in technology make it possible to observe variations in water surface and water height on ever smaller water bodies. This thesis aims to explore the hydrological functioning of water bodies in West Africa, in particular small ones, and to improve their detection using satellite data. In the first part of this thesis, we analyse the hydrological regimes of 37 small water bodies, ranging from 0.04 km² to 37.91 km², located under the Sentinel-3 altimeter tracks in Mali, Burkina Faso and Niger. Using a multi-sensor approach, with optical data from the Sentinel-2 MultiSpectral Instrument (MSI) and altimetry data from the Sentinel-3 Synthetic Aperture Radar Altimeter (SRAL), we estimate the water balance of each water body by comparing water height variations during the dry season to estimated evaporation. This study reveals that 24 water bodies, particularly reservoirs in central Burkina Faso, are experiencing water losses, some of which are explained by human activities such as irrigation. Other water bodies, such as those in the Inner Niger Delta, show inflows attributable to groundwater or river flows. We can also detect changes in water regimes, highlighting artificial reservoirs that have been abandoned or are subject to exceptional water losses following damage to infrastructure. These results demonstrate the potential of satellite data for studying the hydrological regime of small water bodies in semi-arid regions, and open up interesting prospects for exploiting SWOT data, a wide-swath altimeter that will make it possible to monitor all water bodies. The second part of the thesis focuses on improving the detection of surface waters in West Africa. We propose a new approach designed to fill the gaps in currently available global databases that fail to identify certain water bodies, particularly those with vegetation. This method is based on deep learning and uses a CNN-type neural network with U-Net architecture and Sentinel-2 MSI optical data. Despite the small amount of training data, our model achieves very good performance (F1-score of 97 %) and is capable of detecting surface waters even those covered with aquatic vegetation. The results enable us to classify all the water bodies in this region, of which 85 % have a surface smaller than 0.1 km², and to identify their typology, with the vast majority being covered with aquatic vegetation or turbid waters. In conclusion, this thesis offers an innovative perspective on the monitoring of surface water resources in West Africa, more specifically small water bodies, characterized by different water balance and different typologies. It also provides accessible and reproducible methods for studying these phenomena.L'Afrique de l'Ouest abrite un grand nombre de plans d'eau, incluant des lacs, des mares et des réservoirs, souvent de petite taille, jouant un rôle essentiel dans la vie des populations locales. Malgré leur importance, ces ressources sont peu étudiées, notamment en raison du manque de données de terrain. La télédétection permet l'observation des eaux de surfaces continentales, mais la résolution spatio-temporelle des instruments a longtemps été un obstacle au suivi de ces petits objets très dynamiques dans le temps. Aujourd'hui, les améliorations technologiques permettent d'observer les variations de surface et de hauteur d'eau sur des eaux de surface de plus en plus petites. Cette thèse vise à explorer le fonctionnement hydrologique des plans d'eau en Afrique de l'Ouest, en particulier les plans d'eau de petite taille, et à améliorer leur détection, grâce à l'utilisation de données satellites. En première partie de cette thèse, nous analysons les régimes hydrologiques de 37 petits plans d'eau, allant de 0.04 km² à 37.91 km², situés sous les traces altimétriques de Sentinel-3, au Mali, au Burkina Faso et au Niger. Par une approche multi-capteurs, à l'aide de données optiques du Sentinel-2 MultiSpectral Instrument (MSI) et de données altimétriques du Sentinel-3 Synthetic Aperture Radar Altimeter (SRAL), nous estimons le bilan hydrologique de chaque plan d'eau en comparant les variations de hauteurs d'eau en saison sèche avec l'évaporation estimée. Cette étude révèle que 24 plans d'eau, notamment les réservoirs dans le centre du Burkina Faso, connaissent des pertes d'eau dont certaines sont expliquées par des activités humaines telles que l'irrigation. D'autres plans d'eau montrent des apports, attribuables aux nappes souterraines ou aux écoulements des cours d'eau, comme les plans d'eau situés dans le delta intérieur du Niger. Nous pouvons également détecter les modifications de régimes, mettant en évidence des réservoirs artificiels abandonnés ou sujets à des pertes en eau exceptionnelles suite à des dégâts sur les infrastructures. Ces résultats démontrent les potentialités des données satellites pour l'étude du fonctionnement hydrologique de petits plans d'eau en région semi-aride et ouvrent des perspectives intéressantes pour l'exploitation des données SWOT, altimètre à large fauchée qui permettra de suivre l'ensemble des plans d'eau. La deuxième partie de la thèse se concentre sur l'amélioration de la détection des eaux de surface en Afrique de l'Ouest. Nous proposons une nouvelle approche conçue pour combler les lacunes des bases de données globales disponibles actuellement qui ne parviennent pas à identifier certains plans d'eau, en particulier ceux avec de la végétation. Cette méthode est basée sur l'apprentissage profond et utilise un réseau de neurones à convolution à architecture U-Net avec des données optiques Sentinel-2 MSI. Malgré le faible nombre de données d'apprentissage, notre modèle atteint une très bonne performance (F1-score de 97 %) et est capable de détecter des eaux de surface à partir de 0.002 km², même couvertes de végétation aquatique. Les résultats de cette méthode de détection nous permettent de classifier tous les plans d'eau de cette région, dont 85 % ont une surface inférieure à 0.1 km², et d'identifier leur typologie avec la grande majorité des eaux avec de la végétation aquatique ou turbides. En conclusion, cette thèse offre une perspective innovante sur le suivi des ressources en eau de surface de l'Afrique de l'Ouest, plus particulièrement les petits plans d'eau, caractérisés par différents fonctionnements hydrologiques et différentes typologies. De plus, elle met à disposition des méthodes accessibles et reproductibles pour étudier ces phénomènes

Suivi des plans d'eau en Afrique de l'Ouest par télédétection : analyse du régime hydrologique par une approche multi-capteurs et classification par réseau de neurones

West Africa count numerous water bodies, including lakes, ponds and reservoirs, often small ones, crucial for local populations which use them on a daily basis. Despite their importance, these resources are under-studied, mainly due to a lack of in situ data. Remote sensing data allow studying continental surface waters, but the spatial and temporal resolution of the instruments has often been an obstacle to studying these small, highly dynamic objects over time. Today, improvements in technology make it possible to observe variations in water surface and water height on ever smaller water bodies. This thesis aims to explore the hydrological functioning of water bodies in West Africa, in particular small ones, and to improve their detection using satellite data. In the first part of this thesis, we analyse the hydrological regimes of 37 small water bodies, ranging from 0.04 km² to 37.91 km², located under the Sentinel-3 altimeter tracks in Mali, Burkina Faso and Niger. Using a multi-sensor approach, with optical data from the Sentinel-2 MultiSpectral Instrument (MSI) and altimetry data from the Sentinel-3 Synthetic Aperture Radar Altimeter (SRAL), we estimate the water balance of each water body by comparing water height variations during the dry season to estimated evaporation. This study reveals that 24 water bodies, particularly reservoirs in central Burkina Faso, are experiencing water losses, some of which are explained by human activities such as irrigation. Other water bodies, such as those in the Inner Niger Delta, show inflows attributable to groundwater or river flows. We can also detect changes in water regimes, highlighting artificial reservoirs that have been abandoned or are subject to exceptional water losses following damage to infrastructure. These results demonstrate the potential of satellite data for studying the hydrological regime of small water bodies in semi-arid regions, and open up interesting prospects for exploiting SWOT data, a wide-swath altimeter that will make it possible to monitor all water bodies. The second part of the thesis focuses on improving the detection of surface waters in West Africa. We propose a new approach designed to fill the gaps in currently available global databases that fail to identify certain water bodies, particularly those with vegetation. This method is based on deep learning and uses a CNN-type neural network with U-Net architecture and Sentinel-2 MSI optical data. Despite the small amount of training data, our model achieves very good performance (F1-score of 97 %) and is capable of detecting surface waters even those covered with aquatic vegetation. The results enable us to classify all the water bodies in this region, of which 85 % have a surface smaller than 0.1 km², and to identify their typology, with the vast majority being covered with aquatic vegetation or turbid waters. In conclusion, this thesis offers an innovative perspective on the monitoring of surface water resources in West Africa, more specifically small water bodies, characterized by different water balance and different typologies. It also provides accessible and reproducible methods for studying these phenomena.L'Afrique de l'Ouest abrite un grand nombre de plans d'eau, incluant des lacs, des mares et des réservoirs, souvent de petite taille, jouant un rôle essentiel dans la vie des populations locales. Malgré leur importance, ces ressources sont peu étudiées, notamment en raison du manque de données de terrain. La télédétection permet l'observation des eaux de surfaces continentales, mais la résolution spatio-temporelle des instruments a longtemps été un obstacle au suivi de ces petits objets très dynamiques dans le temps. Aujourd'hui, les améliorations technologiques permettent d'observer les variations de surface et de hauteur d'eau sur des eaux de surface de plus en plus petites. Cette thèse vise à explorer le fonctionnement hydrologique des plans d'eau en Afrique de l'Ouest, en particulier les plans d'eau de petite taille, et à améliorer leur détection, grâce à l'utilisation de données satellites. En première partie de cette thèse, nous analysons les régimes hydrologiques de 37 petits plans d'eau, allant de 0.04 km² à 37.91 km², situés sous les traces altimétriques de Sentinel-3, au Mali, au Burkina Faso et au Niger. Par une approche multi-capteurs, à l'aide de données optiques du Sentinel-2 MultiSpectral Instrument (MSI) et de données altimétriques du Sentinel-3 Synthetic Aperture Radar Altimeter (SRAL), nous estimons le bilan hydrologique de chaque plan d'eau en comparant les variations de hauteurs d'eau en saison sèche avec l'évaporation estimée. Cette étude révèle que 24 plans d'eau, notamment les réservoirs dans le centre du Burkina Faso, connaissent des pertes d'eau dont certaines sont expliquées par des activités humaines telles que l'irrigation. D'autres plans d'eau montrent des apports, attribuables aux nappes souterraines ou aux écoulements des cours d'eau, comme les plans d'eau situés dans le delta intérieur du Niger. Nous pouvons également détecter les modifications de régimes, mettant en évidence des réservoirs artificiels abandonnés ou sujets à des pertes en eau exceptionnelles suite à des dégâts sur les infrastructures. Ces résultats démontrent les potentialités des données satellites pour l'étude du fonctionnement hydrologique de petits plans d'eau en région semi-aride et ouvrent des perspectives intéressantes pour l'exploitation des données SWOT, altimètre à large fauchée qui permettra de suivre l'ensemble des plans d'eau. La deuxième partie de la thèse se concentre sur l'amélioration de la détection des eaux de surface en Afrique de l'Ouest. Nous proposons une nouvelle approche conçue pour combler les lacunes des bases de données globales disponibles actuellement qui ne parviennent pas à identifier certains plans d'eau, en particulier ceux avec de la végétation. Cette méthode est basée sur l'apprentissage profond et utilise un réseau de neurones à convolution à architecture U-Net avec des données optiques Sentinel-2 MSI. Malgré le faible nombre de données d'apprentissage, notre modèle atteint une très bonne performance (F1-score de 97 %) et est capable de détecter des eaux de surface à partir de 0.002 km², même couvertes de végétation aquatique. Les résultats de cette méthode de détection nous permettent de classifier tous les plans d'eau de cette région, dont 85 % ont une surface inférieure à 0.1 km², et d'identifier leur typologie avec la grande majorité des eaux avec de la végétation aquatique ou turbides. En conclusion, cette thèse offre une perspective innovante sur le suivi des ressources en eau de surface de l'Afrique de l'Ouest, plus particulièrement les petits plans d'eau, caractérisés par différents fonctionnements hydrologiques et différentes typologies. De plus, elle met à disposition des méthodes accessibles et reproductibles pour étudier ces phénomènes

Monitoring water bodies in West Africa using remote sensing data : analysis of hydrological regime with a multi-sensor approach and classification with neural networks

L'Afrique de l'Ouest abrite un grand nombre de plans d'eau, incluant des lacs, des mares et des réservoirs, souvent de petite taille, jouant un rôle essentiel dans la vie des populations locales. Malgré leur importance, ces ressources sont peu étudiées, notamment en raison du manque de données de terrain. La télédétection permet l'observation des eaux de surfaces continentales, mais la résolution spatio-temporelle des instruments a longtemps été un obstacle au suivi de ces petits objets très dynamiques dans le temps. Aujourd'hui, les améliorations technologiques permettent d'observer les variations de surface et de hauteur d'eau sur des eaux de surface de plus en plus petites. Cette thèse vise à explorer le fonctionnement hydrologique des plans d'eau en Afrique de l'Ouest, en particulier les plans d'eau de petite taille, et à améliorer leur détection, grâce à l'utilisation de données satellites. En première partie de cette thèse, nous analysons les régimes hydrologiques de 37 petits plans d'eau, allant de 0.04 km² à 37.91 km², situés sous les traces altimétriques de Sentinel-3, au Mali, au Burkina Faso et au Niger. Par une approche multi-capteurs, à l'aide de données optiques du Sentinel-2 MultiSpectral Instrument (MSI) et de données altimétriques du Sentinel-3 Synthetic Aperture Radar Altimeter (SRAL), nous estimons le bilan hydrologique de chaque plan d'eau en comparant les variations de hauteurs d'eau en saison sèche avec l'évaporation estimée. Cette étude révèle que 24 plans d'eau, notamment les réservoirs dans le centre du Burkina Faso, connaissent des pertes d'eau dont certaines sont expliquées par des activités humaines telles que l'irrigation. D'autres plans d'eau montrent des apports, attribuables aux nappes souterraines ou aux écoulements des cours d'eau, comme les plans d'eau situés dans le delta intérieur du Niger. Nous pouvons également détecter les modifications de régimes, mettant en évidence des réservoirs artificiels abandonnés ou sujets à des pertes en eau exceptionnelles suite à des dégâts sur les infrastructures. Ces résultats démontrent les potentialités des données satellites pour l'étude du fonctionnement hydrologique de petits plans d'eau en région semi-aride et ouvrent des perspectives intéressantes pour l'exploitation des données SWOT, altimètre à large fauchée qui permettra de suivre l'ensemble des plans d'eau. La deuxième partie de la thèse se concentre sur l'amélioration de la détection des eaux de surface en Afrique de l'Ouest. Nous proposons une nouvelle approche conçue pour combler les lacunes des bases de données globales disponibles actuellement qui ne parviennent pas à identifier certains plans d'eau, en particulier ceux avec de la végétation. Cette méthode est basée sur l'apprentissage profond et utilise un réseau de neurones à convolution à architecture U-Net avec des données optiques Sentinel-2 MSI. Malgré le faible nombre de données d'apprentissage, notre modèle atteint une très bonne performance (F1-score de 97 %) et est capable de détecter des eaux de surface à partir de 0.002 km², même couvertes de végétation aquatique. Les résultats de cette méthode de détection nous permettent de classifier tous les plans d'eau de cette région, dont 85 % ont une surface inférieure à 0.1 km², et d'identifier leur typologie avec la grande majorité des eaux avec de la végétation aquatique ou turbides. En conclusion, cette thèse offre une perspective innovante sur le suivi des ressources en eau de surface de l'Afrique de l'Ouest, plus particulièrement les petits plans d'eau, caractérisés par différents fonctionnements hydrologiques et différentes typologies. De plus, elle met à disposition des méthodes accessibles et reproductibles pour étudier ces phénomènes.West Africa count numerous water bodies, including lakes, ponds and reservoirs, often small ones, crucial for local populations which use them on a daily basis. Despite their importance, these resources are under-studied, mainly due to a lack of in situ data. Remote sensing data allow studying continental surface waters, but the spatial and temporal resolution of the instruments has often been an obstacle to studying these small, highly dynamic objects over time. Today, improvements in technology make it possible to observe variations in water surface and water height on ever smaller water bodies. This thesis aims to explore the hydrological functioning of water bodies in West Africa, in particular small ones, and to improve their detection using satellite data. In the first part of this thesis, we analyse the hydrological regimes of 37 small water bodies, ranging from 0.04 km² to 37.91 km², located under the Sentinel-3 altimeter tracks in Mali, Burkina Faso and Niger. Using a multi-sensor approach, with optical data from the Sentinel-2 MultiSpectral Instrument (MSI) and altimetry data from the Sentinel-3 Synthetic Aperture Radar Altimeter (SRAL), we estimate the water balance of each water body by comparing water height variations during the dry season to estimated evaporation. This study reveals that 24 water bodies, particularly reservoirs in central Burkina Faso, are experiencing water losses, some of which are explained by human activities such as irrigation. Other water bodies, such as those in the Inner Niger Delta, show inflows attributable to groundwater or river flows. We can also detect changes in water regimes, highlighting artificial reservoirs that have been abandoned or are subject to exceptional water losses following damage to infrastructure. These results demonstrate the potential of satellite data for studying the hydrological regime of small water bodies in semi-arid regions, and open up interesting prospects for exploiting SWOT data, a wide-swath altimeter that will make it possible to monitor all water bodies. The second part of the thesis focuses on improving the detection of surface waters in West Africa. We propose a new approach designed to fill the gaps in currently available global databases that fail to identify certain water bodies, particularly those with vegetation. This method is based on deep learning and uses a CNN-type neural network with U-Net architecture and Sentinel-2 MSI optical data. Despite the small amount of training data, our model achieves very good performance (F1-score of 97 %) and is capable of detecting surface waters even those covered with aquatic vegetation. The results enable us to classify all the water bodies in this region, of which 85 % have a surface smaller than 0.1 km², and to identify their typology, with the vast majority being covered with aquatic vegetation or turbid waters. In conclusion, this thesis offers an innovative perspective on the monitoring of surface water resources in West Africa, more specifically small water bodies, characterized by different water balance and different typologies. It also provides accessible and reproducible methods for studying these phenomena